Electrochemical Evaluation of Leakage Resistance of Root Canals Filled with two Sealers and three Obturation Techniques (An in-vitro study)
A Thesis Submitted to the Council of the School of Dentistry, Faculty of Medical Sciences, University of Sulaimani in Partial Fulfillment of the Requirement for the Degree of Master of Science in Conservative Dentistry By Ranjdar Mahmood Othman B.D.S Supervised by Prof.Dr.Salam D. Al-Qaisi B.D.S, M.Sc
1432 A.H
2711 K
2011A.D
س ِى ه َّللاِ ان هش ْح ًَٰ ٍِ ان هش ِحيى تِ ْ
.
صدق هللا العظيم سىسج انثقشج األيح ()٣٢
Dedicated to: Memory of my uncle mama Abdulla My lovely wife My beloved son Lalo Great and merciful Father and Mother My Brothers and Sisters
ACKNOWLEGEMENT Thanks and praises to Al-MIGHTY ALLAH for inspiring me and giving me willingness and patience to complete this study. Special thanks and appreciation go to the Ministry of Higher Education and Scientific Research, University of Sulaimani, School of Dentistry for their support and facilities to continue my postgraduate study. All respect and appreciation are due to Dr. Falah A. Hussein, the Dean of School of Dentistry University of Sulaimani, for his continuous support and encouragement. Special thanks are expressed to Dr. Kamal A. Saaed for his support and opening postgraduate study. My deepest gratitude and appreciation go to my supervisor Prof. Dr. Salam D. Al-Qaisi for his great role, advice and efforts in supervising this thesis. I would like to express my thanks to Dr. Shakhwan K. Khoshnaw, chairman of Conservative Dentistry and all teaching staff at Conservative Department for their support and continuous help. My thanks go to Dr. Anwar Ahmad Amin, the director of postgraduate studies for his help and support. I would like to express my thanks to Electricity Department of College of Engineering and Chemistry Department of College of Science for their support to complete this study and to both Yahiya Mahmmad Saaed and Faredoon Wali teaching staff of Electricity department and to Omed Hama Kareem teaching assistant of Chemistry department.
I
My thanks go to Dr. Wadih Al-Qaisi and Dr. Mohammad Kareem for their advice about statistical analysis associated with this research. Words of appreciation are due to Jamal Abdul, Dr.Rishwan Omar, Dr. Mohammed Taha Baban, Dr. Xoshnaw Mariff, Dr.Shawbo Mahmmad and Dr. Bamo Namiq. I would like to express my highest thankfulness to my wife for her patience and continuous care during the period of this study.
II
Abstract The present study was carried out to evaluate the leakage resistance of root canal filled with AH26 and Endofill sealer and obturated by Thermafill, cold lateral condensation and single cone techniques and assessed by electrochemical method. Sixty extracted teeth with single straight root with closed apices were selected for the study. The anatomical crowns of all teeth were removed at cemento-enamel junction at the level of 16mm. The roots were then divided into six groups (A1, A2, B1, B2, C and control group) and each group consisting of 10 roots. The control group consisted of 10 roots, 5 positive and 5 negative roots. All roots were instrumented using rotary ProTaper NiTi instrument, irrigated with 5.25% NaOCl and 17% EDTA then the roots were dried with paper points and then filled as following: A1: cold lateral condensation with Endofill. A2: cold lateral condensation with AH26. B1: single cone with AH26. B2: single cone with Endofill. C: Thermafill with AH26 with control group. Leakages within the obturated canals were assessed by an electrochemical technique, for 30 days at the time intervals of (0, 5, 10, 15, 20, 25 and 30 days) and the magnitude of the current for each root was directly proportional to extent of leakage. The results of present study were analyzed statistically using (one way-ANOVA and Post Hoc Test- p˂0.05) and showed that all specimens of all groups showed low initial leakage that increased during the test periods. The mean leakage current in AH26 group for all obturation techniques was significantly lower than Endofill sealer for all groups. The mean leakage current for roots that obturated with Thermafill system was significantly less leakage current than cold lateral condensation and single cone III
technique while roots obturated with single cone technique showed significantly more leakage current than other technique while the roots filled with cold lateral condensation technique showed moderate leakage current. The conclusion of this study was that the best apical seal that exhibited more leakage resistance was obtained by using Thermafill obturation with AH26 sealer and the poorest results were observed in single cone technique with Endofill sealer.
IV
List of Contents Title
Page
Acknowledgment
I
Abstract
III
List of contents
V
List of abbreviations
IX
List of tables
XI
List of Figures
XIV
Introduction
1
Aims of the study
4
CHAPTER ONE: REVIEW OF LITERATURE 1. Endodontic Treatment
5
1.1. The goals of endodontic treatment
5
1.2. Cleaning and shaping
5
1.2.1. Biological objectives of cleaning and shaping
6
1.2.2. Technical objectives of cleaning and shaping
6
1.2.3. Root canal instrument classification
6
1.2.4. Root canal instrumentation techniques
7
1.2.4.1. Crown-Down root instrumentation technique
8
1.2.4.2. Rotary NiTi root canal preparation
8
1.2.4.2.1. History of NiTi rotary instruments
9
1.2.4.2.2. Endodontic motors and devices
10
V
1.2.4.2.3. Components of a rotary files
11
1.2.4.2.4. Nickle-Titanum rotary root canal
11
instrumentation systems 1.2.4.2.5. ProTaper
12
1.2.4.2.5.1. Design features of ProTaper rotary files
13
1.2.4.2.5.2. Rotary ProTaper root canal preparation
16
technique 1.3. Root canal irrigation
17
1.3.1. Sodium Hypochlorite (NaOCl)
19
1.3.2. Ethylenediaminetetraacetic acid (EDTA)
21
1.4. Root canal obturation
22
1.4.1. Root canal filling materials
22
1.4.1.1. Requirements of an ideal root canal filling
22
materials 1.4.1.2. Basic compositions of endodontic filling
23
materials 1.4.1.3. Sealers
24
1.4.1.3.1. AH26 sealer
26
1.4.1.3.2. Endofill sealer
28
1.4.2. Root canal obturation techniques
30
1.4.2.1. Cold lateral condensation technique
33
1.4.2.2. Single Cone obturation technique
36
1.4.2.3. Thermafill obturation technique
39
VI
1.5. Assessment the quality of root canal fillings
42
1.5.1. Microleakage study
42
1.5.1.1. Electrochemical microleakage assessment
44
CHAPTER TWO: MATERAIS AND METHODS 2.1. Instruments and Equipments
47
2.2. Materials
48
2.3. Methodology
54
2.3.1. Sample selection
54
2.3.2. Root canal instrumentation
55
2.3.3. Sample grouping
56
2.3.4. Obtuartion of canals
58
2.3.5. Radiographic evaluation of root canal
59
obturation 2.3.6. Leakage assessment by electrochemical method
61
2.4. Data collection and statistical analysis
66
CHAPTER THREE: RESULTS 3. Results
67
CHAPTER FOUR: DISCUSSION 4. Discussion
89
CHAPTER FIVE: CONCLUSIONS AND SUGGESTIONS 5.1. Conclusions
95
5.2. Suggestions
96
VII
References
97
Appendices
112
انخالصح تىخته
VIII
List of Abbreviations 3D
Three Dimension
Ω
Resistor (Ohm)
AVO
Ampere-Volt-Ohm
CHX
Chlorhexidine
CLC
Cold Lateral Condensation
CT
Computed Tomography
DC
Direct Current
DF
Degree of Freedom
EDTA
Ethylenediaminetetraacetic acid
GG
Gates Glidden
GP
Gutta-Percha
GT
Greater Taper
H.S
Highly Significant
ISO
International Standards Organizations
LC
Lateral Condensation
LSD
Least Significant Difference
LSX
Light Speed Instruments
µA
Microampere
MTA
Mineral trioxide aggregate
MTAD
Mixture Tetracycline Citric Acid and Detergent
NaCl
Normal Saline
IX
NaOCl
Sodium Hypochlorite
NiTi
Nickel Titanum
N.S
Non Significant
PGFA
Percentage of Gutta-Percha Filled Area
ProTaper
Progressive Taper
r.p.m
Rotation per minute
SAF
Self Adjusting File
SD
Standard Deviation
SC
Single Cone
SCT
Spiral Computed Tomography
W/W
Weight to weight ratio
V
Volt
ZnOE
Zinc Oxide Eugenol
X
List of Tables No.
Title
Page
1.1.
Design specification of ProTaper instruments
13
1.2.
Requirements of ideal root canal sealers
25
3.1.
Mean microleakage currents (µA) and Standard Deviation of
68
all groups immediately at time of (0 day)
3.2.
Analysis of variance (ANOVA) for microleakage currents at
68
time of (0 day)
3.3.
Least Significant Difference (LSD) test for microleakage
69
currents of all groups at time of (0 day)
3.4.
Mean microleakage currents (µA) and Standard Deviation of
70
all groups at time of (5 days)
3.5.
Analysis of variance (ANOVA) for microleakage currents at
70
time of (5 days)
3.6.
Least Significant Difference (LSD) test for microleakage
71
currents of all groups at time of (5 days)
3.7.
Mean microleakage currents (µA) and Standard Deviation of
72
all groups immediately at time of (10 days)
3.8.
Analysis of variance (ANOVA) for microleakage currents at
72
time of (10 days)
3.9.
Least Significant Difference (LSD) test for microleakage
73
currents of all groups at time of (10 days)
3.10.
Mean microleakage currents (µA) and Standard Deviation of all groups immediately at time of (15 days) XI
74
3.11.
Analysis of variance (ANOVA) for microleakage currents at
74
time of (15 days)
3.12.
Least Significant Difference (LSD) test for microleakage
75
currents of all groups at time of (15 days)
3.13.
Mean microleakage currents (µA) and Standard Deviation of
76
all groups immediately at time of (20 days)
3.14.
Analysis of variance (ANOVA) for microleakage currents at
76
time of (20 days)
3.15.
Least Significant Difference (LSD) test for microleakage
77
currents of all groups at time of (20 days)
3.16.
Mean microleakage currents (µA) and Standard Deviation of
78
all groups immediately at time of (25 days)
3.17.
Analysis of variance (ANOVA) for microleakage currents at
78
time of (25 days)
3.18.
Least Significant Difference (LSD) test for microleakage
79
currents of all groups at time of (25 days)
3.19.
Mean microleakage currents (µA) and Standard Deviation of
80
all groups immediately at time of (30 days)
3.20.
Analysis of variance (ANOVA) for microleakage currents at
80
time of (30 days)
3.21.
Least Significant Difference (LSD) test for microleakage
81
currents of all groups at time of (30 days)
3.22.
Comparison of Mean microleakage currents and Standard
82
deviation of Cold Lateral condensation technique with Endofill sealer (group A1) at time interval from (0 to 30 days)
3.23.
Comparison of Mean microleakage currents and Standard XII
83
deviation of Cold Lateral condensation technique with AH26 sealer (group A2) at time interval from (0 to 30 days)
3.24.
Comparison of Mean microleakage currents and Standard
84
deviation of Single Cone obturation technique with AH26 sealer (group B1) at time interval from (0 to 30 days)
3.25.
Comparison of Mean microleakage currents and Standard
85
deviation of Single Cone obturation technique with Endofill sealer (group B2) at time interval from (0 to 30 days)
3.26.
Comparison of Mean microleakage currents and Standard
86
deviation of Thermafill obturation technique with AH26 sealer (group C) at time interval from (0 to 30 days)
3.27.
Comparison of Mean microleakage currents and Standard deviation of Positive Controls group at time interval from (0 to 30 days)
XIII
87
List of Figures No.
Title
Page
1.1.
Components of a rotary file in general
11
1.2.
The ProTaper instruments have a convex triangular cross-
15
section which improves cutting efficiency while maximizing core strength
1.3.
ProTaper files perform smoothly, efficiently and safely as a
15
result of their progressively tapered design and continuously changing pitch and helical angle
1.4.
ProTaper series
16
1.5.
The Protaper System contains 8 rotary files; 3 shaping files, SX,
17
S1 and S2, and 5 finishers (F1 to F5)
1.6.
Classic spectrum of filling techniques, emphasizing the
31
desirability of minimum sealer volume, from pastes only (least desirable); through single cones with paste, and cold lateral condensation, to thermoplastic compaction
1.7.
Matched, ergonomic shaping files and filling cones may
37
inadvertently promote single cone filling techniques
2.1.
The materials and instruments used in the study
50
2.2.
The solutions and syringes used in the study
50
2.3.
Endofill and AH26 sealer used in the study
51
2.4.
Electronic controlled gear reduction rotary device and
51
Thermaprep plus oven
2.5.
Protaper obturator, paper point and gutta-percha and Protaper cleaning and shaping file (Sx, S1, S2, F1, F2, F3 and F4) XIV
52
2.6.
Bio-Ray Prox and digital sensor x-ray
52
2.7.
Electrochemical leakage test circuit component: Platinum
53
counter electrode, Standard resistor (100) Ohm, AVO meter and Power supply of 20 V DC.
2.8.
Tooth sectioning at cementoenamal junction to average
54
length of 16mm.
2.9.
The ProTaper shaping technique. The ProTaper sequence is
56
always the same regardless of the length, diameter or curvature of the canal
2.10.
Sample grouping
57
2.11.
Samples of radiographic evaluation of root canal obturation
60
2.12.
Radiographical assessment of attachment of wire to remaining
61
root canal filling materials
2.13.
Tooth and wire sealed in place with sticky wax, tooth with wire
62
covered with three layer of nail varnish except of (2-3) apically left patent anda schematic diagram of tested tooth
2.14.
Roots are fixed with silicone on plastic container leaving about
63
9mm to be immersed in normal saline solution
2.15.
A schematic diagram of the electrochemical leakage test circuit
64
2.16.
Electrochemical leakage test circuit
65
3.1.
Graph Representing Electrochemical Microleakage Currents
82
for Test (group A1) from (0 to 30 days)
3.2.
Graph Representing Electrochemical Microleakage Currents XV
83
for Test (group A2) from (0 to 30 days).
3.3.
Graph Representing Electrochemical Microleakage Currents
84
for Test (group B1) from (0 to 30 days)
3.4.
Graph Representing Electrochemical Microleakage Currents
85
for Test (group B2) from (0 to 30 days)
3.5.
Graph Representing Electrochemical Microleakage Currents
86
for Test (group C) from (0 to 30 days)
3.6.
Graph Representing Electrochemical Microleakage Currents
87
for Test Positive Controls group from (0 to 30 days)
3.7.
Graph Representing Electrochemical Microleakage Currents for All Test Groups from (0 to 30 Days)
XVI
88
Introduction
Introduction
Introduction: The goals of modern endodontic therapy are cleaning, shaping, disinfection and three dimensional obturation of the root canal system that does not allow leakage and promotes periapical healing (Oddoni et al, 2008). Apical leakage has been defined as the passage of bacteria, fluids, and chemical substances between the dentinal wall and the root canal filling material, and these results from the presence of space at the interface of the filling material and root canal wall and is considered to be a common cause for endodontic therapy failure (Hirai et al, 2010). Many different materials and techniques have been developed for instrumentation and obturation of root canals and during the last 15 years, root canal preparation with rotary nickel-titanium (NiTi) instruments has become popular and it has been reported that rotary NiTi instruments shape the root canals easily, rapidly, and more predictably while reducing procedural errors and maintaining the original curvature of the root canals, additionally preparation of the root canal with rotary instruments may improve the adaptation between the gutta-percha point and the canal wall, because the flexible NiTi instruments may result in less straightening and flaring of curved canals compared with the use of stainless steel (Tasdemir et al, 2009). When filling the root-canal system, the sealer plays an important role in reducing microleakage and an ideal root canal sealer should be biocompatible, antibacterial, nontoxic, and radiopaque, and it should also hermetically seal the root canal system, be dimensionally stable, and should have good adhesion to the root canal wall. Zinc oxide eugenol has been used for several decades, owing to its physicochemical properties and antimicrobial activity. Resin sealers have a long history of use to provide adhesion. Although excellent apical sealing has been achieved with this sealer while most
1
Introduction
available root canal filling materials are not able to completely seal the root canal system for a long period of time. (Zhang et al, 2009) and (Yilmaz et al, 2009). Although there are many different obturation techniques, there is no generally accepted method for the delivery of gutta-percha to the canal. Lateral compaction of gutta-percha remains to be the most frequently used and clinically proven technique of all root canal obturation techniques and another approach is the tapered single-cone technique, which has recently been reviewed with the greater taper master cones that closely match the geometry of nickel-titanium (Ni-Ti) rotary systems and the use of tapered cones with sealer may provide 3-dimensional obturation of the root canal without the requirement for accessory cones or time spent on lateral compaction when the root canal is enlarged with rotary instruments (Yilmaz et al, 2009). Thermoplasticized gutta-percha techniques have been advocated for root canal obturation because they may provide a more homogeneous obturation and better adaptation to the root canal walls, which might result in a lower rate of leakage compared with lateral condensation (Brosco et al, 2008). A variety of experimental models are used to detect and measure leakage along endodontic fillings, such as dye penetration, clearing of the teeth, radioisotope tests, bacterial penetration, electrochemical tests, fluid filtration, and the glucose penetration model (Hirai et al, 2010). An electrochemical microleakage test was described by Jacobsen and Van Fraunhofer in 1976. In this model, an electric current is passed through a root-canal filling. By measuring impedance values of this circuit, inferences about leakage can be made (Karagenc et al, 2006). Electrochemical leakage tests offer advantages in terms of speed, accuracy and efficiency, as well as their ability to perform longitudinal studies, since electrochemical 2
Introduction
leakage data are quantitative measurements, they are easy to compare and analyze (von Fraunhofer and Kurtzman, 2008). This study was undertaken to study the leakage resistance of root canals filled with AH26 and Endofill sealer and obturated with cold lateral condensation, single cone and Thermafill obturation techniques.
3
Aims of the study The purposes of this study were to compare electrochemical leakage resistances of root canals prepared by rotary ProTaper instrumentation technique and filled by: 1. Cold lateral condensation technique with gutta-percha using Endofill and AH26 sealers. 2. Single cone technique with single ProTaper gutta-percha using Endofill and AH26 sealers. 3. Solid core technique using Thermafill with AH26 sealer.
4
Chapter One Review of Literature
Review of Literatures
1. Endodontic Treatment: 1.1. The goals of endodontic treatment: The main objective of endodontic therapy is to prevent and, when required, to cure endodontic disease, apical periodontitis, preserve the tooth as a functional unit within a functioning dentition and the achievement of these goals depends on several factors: Elimination of surviving microorganisms in the root canal system through effective cleaning and shaping procedures. Creation of a tight three-dimensional seal with an inert filling material. Blockage of any communication between the oral cavity and the periradicular tissue through a high quality coronal restoration (Yeng et al, 2007) & (Cantatore et al, 2009).
1.2. Cleaning and shaping: Preparation of the root canal system is recognized as being one of the most important stages in root canal treatment and about 40 years ago; Schilder introduced the concept and the term “Cleaning and Shaping”. Cleaning refers to “the removal of all contents of the root canal system before and during shaping: organic substrates, food, micro flora, bacterial byproducts, caries, pulp stones, dense collagen, previous root canal filling material, and dentinal filings from root canal preparations” and shaping refers to a specific cavity form that allows: Facilitates irrigants to flow through the entire root canal system. Facilitates obturation material to flow and seal the entire root canal system. (Hulsmann et al, 2005) & (Jacob, 2006).
5
Review of Literatures
1.2.1. Biological objectives of cleaning and shaping: (Micro) biologically, the goal of instrumentation and irrigation is to remove and/or kill all microorganisms in the root canal system, and neutralize any antigenic/ biological potential of the microbial components remaining in the canal (Haapasalo et al, 2005).
1.2.2. Technical objectives of cleaning and shaping: Young et al (2007) showed that the technical goals of canal preparation are directed toward shaping the canal so as to achieve the biological objectives and to facilitate placement of a high quality root filling and outlined several mechanical objectives for optimal instrumentation: Continuously tapering funnel from the access cavity to apical foramen. The root canal preparation should maintain the path of the original canal. The apical foramen should remain in its original position. The apical opening should be kept as small as practical.
1.2.3. Root canal instrument classification: Hargreaves and Cohen (2011) showed that endodontic instruments for root canal preparation can be divided into six groups: Group I: Hand- and finger-operated instruments, such as barbed broaches, K-type and H-type instruments. Group II: Low-speed instruments on which the latch type of attachment is part of the working section. Typical instruments in this group are Gates-Glidden (GG) burs and Peeso reamers and they are typically used in the coronal part of the canal and never used in a canal curvature.
6
Review of Literatures
Group III: Engine-driven nickel-titanium rotary instruments and they consist of a rotating blade that can safely be operated in, and adapt itself to, curved root canals and most engine-driven instruments available today belong to this group. Group IV: Engine-driven instruments that adapt themselves three-dimensionally to the shape of the root canals, like other nickel-titanium instruments, they adapt also to the cross-section of the root canal and there is currently only one instrument in this group: the self-adjusting file (SAF; ReDent-Nova, Raanana, Israel). Group V: Engine-driven reciprocating instruments. Group VI: Ultrasonic instruments.
1.2.4. Root canal instrumentation techniques: Basically, there are two approach used for biomechanical preparation, either starting at the apex with fine instruments and working up to the orifice with progressively larger instruments, this is step back technique or starting at the orifice with larger instrument and working up to apex with smaller instruments and this is crown down technique and various other techniques have been modified out of these two basic technique (Garg and Garg, 2007). Peters (2004) showed that there is three main issues are presently considered most challenging and controversial in root canal shaping: Identification, accessing, and enlargement of the main canals without procedural errors Establishing and maintaining adequate working lengths throughout the shaping procedure Selection of preparation sizes and overall geometries that allow adequate disinfection and subsequent obturation.
7
Review of Literatures
1.2.4.1. Crown-down root canal instrumentation technique: With the advent of rotary powered instrumentation and introduction of Nickel Titanium instruments, the crown-down preparation has become more popular and using of flexible files rotating in curved canal require unimpeded space, and widening this space from the crown down seems the logical solution (Ingle, 2005). In the crown-down technique, International Standards Organization (ISO) instruments with varying D0 diameters are generally selected and utilized from the bigger to smaller sizes. In general, the preparation is initiated at the orifice, continued through the body of the canal, and then terminated at the canal‟s most apical extent. As such, dentin is sequentially removed from the coronal, then the middle, and finally from the apical one third of a canal (Ruddle, 2007). This technique prevents transfer of bacteria from the coronally infected root canal segments into apical, no inflamed areas, because the initial procedure removes necrotic and infected tissues from the coronal and middle canal segments and this accounts for the fact that the occurrence of post-endodontic pain is significantly less than after the step-back technique and in addition, after coronal expansion using Gates drills, apical root canal segments are tactily better achieved and the rinsing cannula extends deep into the root canal and the rinsing supports manual instrumentation effectively also this technique enlarges canals incrementally so less vertical force and torque were created and that instrument tips had less contact with dentin and less stress during the early phases of instrumentation(Beer et al, 2006) and(Fiore, 2007).
1.2.4.2. Rotary NiTi root canal preparation: The introduction of nickel-titanium (Ni-Ti) files made possible to provide more regular preparations because these instruments have high flexibility, low elasticity
8
Review of Literatures
modulus and shape memory, which lead these files to producing fewer mistakes during instrumentation of narrow and curved canals (Miranzi et al, 2011). The use of engine-driven nickel-titanium (NiTi) root canal instruments has many advantages over hand instrumentation, including less canal transportation, less blockage, less time requiring, and more dentin-conserving canal shapes (Bardsley et al, 2011).
1.2.4.2.1. History of NiTi rotary instruments: Vaudt et al (2007) showed that from more than 100 years ago, the first endodontic handpiece was developed with the aim of reducing the treatment time and simplifying the preparation procedure. Furthermore, it was hopped the efficiency and accuracy of endodontic procedure will be improved. As early as 1889, William H Rollins used specially designed needles, which are mounted in a rotary handpeice. A new era in handpeice design began with introduction of Canal Finder System (now distributed by S.E.T., Grobenzell Germany) by Gue Levy in 1984. This was first endodontic hanpeice with partially flexible motion. NiTi alloy were first developed in 1962 and later commercialized under trade name of Nitinol, an acronym of Nickle Titanum Naval Ordance Laboratory. Nitinol is one of the main three types of shape memory alloys, also known as memory metals. In 1988 this alloy found its way in endodontic when Walia introduced Nitinol root canal hand files. The NiTi alloys used for manufacturing root canal instruments consist of approximately 55% (w/w) nickel and 45% (w/w) titanium, and is given generic name 55- Nitinol and NiTi files have a two to three times higher elastic flexibility in bending and torsion as well as superior resistance to corrosion compared with stainless steel files.
9
Review of Literatures
Don‟t Start and Stop: sudden changes in the direction of a rotary caused by the operator must be avoided. A smooth gentle reaming motion is most efficient; rotaries should be inserted and withdrawn from a canal while rotating. Length Control is Critical: working length should be well established and controlled, as should the actual length of the file.
1.2.4.2.2. Endodontic motors & devices: Engine-driven instruments can be used in three types of contra-angle handpieces: a full rotary handpiece, mostly latch grip, a reciprocating/quarter-turn handpiece, or a special handpiece that imparts a vertical stroke but with an added reciprocating quarter turn that "cuts in" when the instrument is stressed and these all are powered by electric or air-driven motors (Ingle, 2008). To avoid fractures as much as possible, in recent years highly soffisticated endodontic motors have been introduced on the market, with which it possible to control the speed as well as the maximum torque and to keep the speed constant, the torque varies continuously depending on the cutting difficulty and the instruments progression and ach instrument however, has a maximum torque security limit which should not be exceeded and importance of being able to regulate the maximum utilizable torque that can be reached for that instrument (type, size) for specific work conditions (original anatomy, dentine hardness)(Castellucci, 2005).
10
Review of Literatures
1.2.4.2.3. Components of a rotary file (Fig. 1.1):
Fig. (1.1): Components of a rotary file in general (McSpadden, 2007).
1.2.4.2.4. Nickle-Titanum rotary root canal instrumentation systems: Hargreaves & Cohen (2011) showed that the most NiTi rotary instrument systems used in endodontic listed as follows: Light Speed instruments LSX (Light Speed Technology, San Antonio, TX, USA). ProFile (Dentsply maillefer, Ballaigues, Switzerland). GT Files (Dentsply maillefer, Ballaigues, Switzerland). HERO 642 (Micro Mega, Besancon, France). ProTaper (Dentsply maillefer, Ballaigues, Switzerland). Quentc system (SC, LX, SybronEndo). K3 (SybronEndo, West Collins, CA, USA). FlexMaster (VDW, Munich, Germany). 11
Review of Literatures
Race (FKG, Dentaire, La-chaux-de-Fonds, Switzerland). Mtwo (VDW, Munich, Germany).
A wide variety of rotary systems has been developed during the last 15 years, with different blade characteristics, insertion path, conicity, and helical angle. The simplification and constant reproducibility of good preparation results are real advantages of these devices and ProTaper among the current options of rotary systems (Bernardes et al, 2010).
1.2.4.2.5. ProTaper: ProTaper NiTi instruments represent a new generation of instruments for shaping root canals. A unique feature of ProTaper instruments is each one has changing percentage tapers over the length of its cutting blades (Ruddle, 2005). In the progressive ProTaper system, the shaping files (S) have an increasing taper from tip to coronal, where as the finishing files (F) have a decreasing taper and it has been claimed that the increasing taper instruments have enhanced flexibility in the middle region and at the tip, and that the decreasing taper instruments provide a larger taper in the important apical region but make them stiff (Yang et al, 2007). Cheung et al (2007) showed that the original ProTaper system consisted of three „Shaping‟ files (Sx, S1 and S2) and three „Finishing‟ files (F1, F2 and F3). While (Lumley et al, 2008) showed that the ProTaper Universal® System, some modifications have been introduced compared to the first generation of instruments and the most noticeable has been the addition of two larger finishers, F4 and F5 to help shape larger canals and for clinicians who prefer larger apical sizes and one of the most important is the modification of the tip of these instruments, by reduction of the transition angle, to make it less aggressive.
12
Review of Literatures
The ProTaper™ for hand use appeared as an alternative to the ProTaper™ rotary instruments, embodying the same philosophy, indications and sequence, but at a lower cost, for the instrumentation is entirely manual, thereby dispensing with the use of an electric engine (Aguiar and Camara, 2008). According to their manufacturers, ProTaper nickel-titanium rotary instruments were designed to improve cutting efficiency, flexibility, safety and being developed for instrumentation of difficult, constricted, and severely curved canals with a few “shaping” and “finishing” instruments (Martins et al, 2010).
1.2.4.2.5.1. Design features of ProTaper rotary files: Design feature of ProTaper instrument including (no. of instruments/set, tip size, size increments, r.p.m recommended and lengths) which can be summarized in table (1.1) (Hargreaves & Cohen, 2011).
Table (1.1): Design specification of ProTaper instruments (Hargreaves & Cohen, 2011). No. of
Tip sizes
instruments/set 8 (3 shaping files; Sx, S1 and S2; 5 finishing files; F1, F2,
19-30
Size
r.p.m
increments
(recommended)
Vary along the working part of an individual instrument
150 to 350 minimal axial force, low to medium torque to fracture, varying working torque
F3, F4 and F5).
13
Lengths
19, 21, 25 mm
Review of Literatures
ProTaper instruments have convex triangular cross section with no radial lands and this feature decreases the rotational friction between the blade of the file and dentin, enhances the cutting action, and improves safety, as compared to radial-landed instruments (Figs. (1.2 A, B))(Castellucci, 2005).The cross section of finishing file F3 is slightly relieved for increased flexibility and the unique design factor is the varying tapers along the instruments‟ long axes and the three shaping files have tapers that increase coronally, and the reverse pattern is seen in the three finishing files (Hargreaves & Cohen, 2011). Pitch is defined as the number of spirals or flutes per unit length on the file and the larger the number of spirals on a file, the greater the file‟s resistance with the lower the resistance provide more efficient the file and the smoother the instrumentation process and consequently, a reamer design (triangular blank) will result in a more efficient cutting instrument (Kurtzman, 2007). ProTaper files have a continuously changing helical angle and pitch over the length of their cutting blades (Figs. 1.3 A, B) changing the pitch and helical angles over the active length of blades optimizes its cutting action and more effectively augers debris out of the canal. Importantly, changing the pitch and helical angles of a file, in conjunction with a progressively tapered design, prevents each instrument from inadvertently screwing into the canal (Castellucci, 2005).
14
Review of Literatures
A
B
Fig. (1.2): A, B. The ProTaper instruments have a convex triangular cross-section which improves cutting efficiency while maximizing core strength (Castellucci, 2005).
A
B
Fig. (1.3): A, B. ProTaper files perform smoothly, efficiently and safely as a result of their progressively tapered design and continuously changing pitch and helical angle (Castellucci, 2005).
The tip diameter of the S1 instrument is 0.19 mm and S2 is 0.2 mm., both S1 and S2 have an increasing taper over the working part, from 2% at D1 to 11% at D14 for S1, and 4% on D1 to 11.5% at D14 for S2 and thus, Shaping instruments exhibit a greater flexibility near their tip than in the middle portion where the taper, and hence the diameter, becomes greater and on the other hand, the Finishing instruments have a relatively large taper in the first 3 mm (compared with the body of the instrument) from 15
Review of Literatures
D0 to D3: 7% for F1, 8% for F2, 9% for F3, 10% for F4 and 11% for F5 with the diameter at the apical few millimeters of the instrument is greater than that of a Shaping instrument, making the finishing instruments stronger with respect to monotonic load, especially in situation where the first 3 mm of the instrument was clamped for testing of ultimate and on the other hand, instruments of a smaller dimension were generally more resistant to cyclic fatigue than larger ones and this may explain the greater amount of defects caused by torsion, i.e. manifesting either as unwinding of flutes or shear failure, observed in Shaping (hand, 18%; engine, 6%) rather than Finishing instruments (hand, 14%; engine, 0%) (Cheung et al, 2006). McSpadden (2007) showed variable taper of ProTaper instrument along the length of each instruments in fig. (1.4).
Fig. (1.4) ProTaper series (McSpadden, (2007)).
1.2.4.2.5.2: Rotary ProTaper root canal preparation technique: The ProTaper universal system is a relatively new addition to the family of NiTi instruments and it comes with unique body design, with multiple taper over the entire length of the instrument and the system consist of eight NiTi engine-driven files as well as hand instruments (SX, S1, S2, F1, F2, F3, F4 and F5) (fig. (1.5)) to enlarge the root 16
Review of Literatures
canal space in a rotary fashion and the three S- instruments are designated as “shaping” instruments, where as the F- are designated as “finishing” (Low, 2010).
Fig. (1.5): The ProTaper System contains 8 rotary files; 3 shaping files, SX, S1 and S2, and 5 finishers (F1 to F5) (Low, 2010). Singla et al (2010) concluded that rotary ProTaper instruments offer the advantage of maximum debridement and resistance to penetration of bacteria specially (Enterococcus faecalis colony-forming units) into dentinal tubules and relied solely on the surface cleaning efficacy over Profile and conventional step-back technique.
1.3. Root canal irrigation: Even with the use of rotary instrumentation, the nickel-titanium instruments currently available only act on the central body of the canal, leaving canal fins, isthmi, and cul-de-sacs untouched after completion of the preparation and these areas might harbor tissue debris, microbes, and their by-products, which might prevent close adaptation of the obturation material and result in persistent periradicular inflammation and therefore, irrigation is an essential part of root canal debridement because it allows for cleaning beyond what might be achieved by root canal instrumentation alone ideal root canal irrigants should meet all the conditions described above for endodontic success so however, there is no one unique irrigant that can meet all these requirements, 17
Review of Literatures
even with the use of methods such as lowering the pH , increasing the temperature, as well as addition of surfactants to increase the wetting efficacy of the irrigant and thus, in contemporary endodontic practice, dual irrigants such as sodium hypochlorite (NaOCl) with ethylenediaminetetraacetic acid (EDTA) or chlorhexidine (CHX) are often used as initial and final rinses to complement the short comings that are associated with the use of a single irrigant and more importantly, these irrigants must be brought into direct contact with the entire canal wall surfaces for effective action particularly for the apical portions of small root canals so the elimination of microorganisms and their by-products from an infected root canal system is essential for a successful endodontic treatment (Gu et al, 2009) and (Gorduysus et al, 2011). Zebnder (2006) showed that the desired functions of irrigating solutions should have: Have a broad antimicrobial spectrum and high efficacy against anaerobic and facultative microorganisms organized in biofilms. Dissolve necrotic pulp tissue remnants and organic debris. Inactivate endotoxin. Be a good lubricant. Prevent the formation of a smear layer during instrumentation or dissolve the latter once it has formed. Nontoxic, no caustic to periodontal tissues and have little potential to cause an anaphylactic reaction.
Jones (2009) listed the factors influencing efficacy of irrigation as follow: Diameter of the irrigating needle Depth of the irrigating needle engaged in root canal Size of enlarged root canal (radius of tube) Viscosity of the irrigating solution (surface tension) 18
Review of Literatures
Velocity of the irrigating solution at the tip of the needle (ultrasonics, sonics) Orientation of the bevel of the needle Temperature.
1.3.1. Sodium hypochlorite (NaOCl): Sodium hypochlorite has been used as an endodontic irrigant since 1920 and nowadays, it is the most popular and the most ideal primary irrigating solution and off all the currently used substances, as it covers more of the requirements for endodontic irrigant than any other known compound (Jacob, 2006). Sodium hypochlorite exhibits a dynamic balance as shown by the following reaction: NaOCl + H2O ↔ NaOH + HOCl ↔ Na+ + OH- + H+ + OClInterpreting these chemical reactions, sodium hypochlorite acts as a solvent for organic and fat degrading fatty acids, transforming them into fatty acid salts (soap) and glycerol (alcohol) that reduces the surface tension of the remaining solution and sodium hypochlorite neutralises amino acids forming water and salt (neutralisation reaction) and with the exit of hydroxyl ions, there is a reduction in pH. Hypochlorous acid, a substance present in sodium hypochlorite solution, when in contact with organic tissue acts as a solvent and releases chlorine that, combined with the protein amino group, forms chloramines (chloramination reaction) that interfere in cell metabolism and other component like hypochlorous acid (HOCl-) and hypochlorite ions (OCl-) lead to amino acid degradation and hydrolysis, while Chlorine (a strong oxidant) presents antimicrobial action inhibiting bacterial enzymes leading to an irreversible oxidation of SH groups (sulphydryl group) of essential bacterial enzymes (Mohammadi (2008)). Spencer et al (2007) showed that sodium hypochlorite is used as an endodontic irrigant as it is an effective antimicrobial and has tissue-dissolving capabilities and it has
19
Review of Literatures
low viscosity allowing easy introduction into the canal architecture, an acceptable shelf life, is easily available and inexpensive. The antimicrobial effectiveness of sodium hypochlorite, based in its high pH (strong base pH ˃ 11), is similar to the mechanism of action of calcium hydroxide (Mohammadi (2008)). For its bactericidal effect, sodium hypochlorite relies heavily on the duration of time retained in the canal and the use of copious volumes of the solution since it is the free chlorine which acts as the disinfecting agent and this is used up rapidly and it has been shown that 5-10 minutes is required to clean and debride a canal and a small volume used for a short contact time will have a limited effect and furthermore, there is evidence that hypochlorite is not effective against all pathogenic bacteria specifically Enterococcusfaecalis which is associated with recalcitrant canals(Bonsor et al, 2006). The weaknesses of NaOCl include the unpleasant taste, toxicity, corrosion to metal and its inability to remove the smear layer by itself, as it dissolves only organic material and the poorer in vivo performance compared with in vitro is probably caused by problems in penetration to the most peripheral parts of the root-canal system such as fins, anastomoses, apical canal, lateral canals, and dentin canals and also, the presence of inactivating substances such as exudate from the periapical area, pulp tissue, dentin collagen, and microbial biomass counteract the effectiveness of NaOCl and recently, it has been shown by in vitro studies that long-term exposure of dentin to a high concentration sodium hypochlorite can have a detrimental effect on dentin elasticity and flexural strength, although there are no clinical data on this phenomenon, it raises the question of whether hypochlorite in some situations may increase the risk of vertical root fracture (Haapasalo et al, 2010).
20
Review of Literatures
1.3.2. Ethylenediaminetetraacetic acid (EDTA): It is an insoluble, odorless, crystalline white liquid and it has certain dentin dissolving effects desirable in all kinds of root canal therapy and this reduces the time necessary for debridement and aids in enlarging narrow or obstructed canals. It has been shown that EDTA has a little capacity to dissolve soft tissue (Taneja et al, 2010). During root canal preparation, the use of endodontic instruments and irrigating solutions produces a smear layer which consisting of dentin shavings, cell debris and pulp remnants, includes two separate strata: a loose superficial deposit and an attached stratum that extends into the dentinal tubules and forms occluding plugs (Moretti et al, 2011). In general, the smear layer consists of a mixture of organic and inorganic debris and the organic portion is dissolved by sodium hypochlorite, the main endodontic irrigant, while to remove the inorganic portion of the smear layer, a decalcifying agent is used, which can be either a chelator or an acid and currently, all the products on the dental market sold to dissolve smear layer are based on ethylenediaminetetraacetic acid (EDTA) or citric acid (De-Deus et al, 2011). Ethylenediaminetetraacetic acid (EDTA) is a chelating agent that has been used in combination with sodium hypochlorite (NaOCl) solutions and this combination provides an antimicrobial action, along with its dissolving and cleaning actions and
final
irrigation with EDTA and NaOCl for 1, 3 and 5 min were equally effective in removing the smear layer from root canals(Santos et al, 2010). Another important consideration in endodontic is the ultimate seal of root canals in order to prevent possible microleakage which may be the cause of the future failure of the root filling and prepared dentin surfaces should be very clean to increase sealing efficiency of obturation and smear layer on root canal walls acts as an intermediate physical barrier and may interfere with adhesion and penetration of sealers into dentinal
21
Review of Literatures
tubules and it was found out that zinc oxide eugenol based root canal sealer failed to enter into dentinal tubules in the presence of smear layer(Bansal and Gupta, 2009).
1.4. Root canal obturation: 1.4.1. Root canal filling materials: One goal of endodontic therapy is root canal obturation, the main objectives of which are hermetically sealing the root canal system and preventing re-infection by microorganisms via the root canal orifice and apical foramen and inadequate root canal obturation can ultimately lead to failure of endodontic treatment (Zhang et al, 2011). In general, a root filling is composed of two materials: a solid core material and a sealer and the most commonly used core material is gutta-percha, which can be placed into the root canal in a cold or a warm state while the main purpose of the root canal sealer is to fill the interface between the core material and the dentine wall, the voids inside the core material and the accessory canals, to serve as a lubricant and to obtain a hermetic apical seal (Salz et al, 2009). Depraet et al (2005) showed that the root filling should fulfill its role in three ways: By blocking communication between the oral cavity and the periradicular tissues (the inhibition of coronal leakage), The entombment of surviving bacterial cells in the root canal system. The inhibition of an influx of fluid from the periapical tissues.
1.4.1.1. Requirements for an ideal root canal filling materials: Bergenholtz et al (2010) listed the requirements of an ideal root canal filling materials as follow: Technical: No shrinkage. 22
Review of Literatures
No solubility in tissue fluids, undisturbed setting in the presence of moisture. Good adhesion/adaptation to dentin or combining materials (cones, sealers). No pores and water absorption. No tooth discoloration. Biological: No general health problems or allergies for patients and dental personnel. No irritation of local tissues. Sterile. Antimicrobial-no enhanced bacterial growth. Stimulation of periapical healing process. Handling: Radiopaque: ISO 6876 (76) requires ˃ 3mm aluminum (dentin has 0.60.7) (radiopacity of dental materials is measured as mm aluminum equivalent). Setting in an adequate time, allowing sufficient time for obturation and radiographic control. Easy to apply and easy to remove (e.g. for post placement or revision using solvents, heat or mechanical instrumentation.
1.4.1.2. Basic composition of endodontic filling materials: Orstavik (2005) classified the root canal filling materials into three types: I.
Core materials which sub classified into:
Gutta-percha. 23
Review of Literatures
Silver points. Resin-based core filling materials (Resilion). II. III.
Sealers. Combination of the two (cones and sealers).
1.4.1.3. Sealers: The filling of a root canal usually requires an endodontic sealer along with the core material and sealers area group of several different materials that vary in composition, structure, setting mechanisms, physical, chemical and mechanical properties(Saleh et al, 2010). The sealers that are commonly used based on: Polyketone. Glass ionomer cement (ex. Ketac-endo, ActiV GP). Zinc oxide eugenol (ZnOE) (ex. Rickerts, Pulp Canal Sealer (EWT), Wach‟s Sealex-Extra, Endo-Fill, MCS Canal Sealer (Iodoform), Endomet (Thymol Iodide), Pulpdent, Canals, Canals-N, Grossman-Type, Roth (801,811, 601, 511, 515), Procosol, Endoseal, Tubliseal, Kerr). Epoxy resin (ex. AH26, Sealer 26, AH plus, EndoRez, Topseal, Epiphany, Diaket). Calcium hydroxide (ex. CRCS, Acroseal, Sealapex, Apexit). Formaldehyde (ex. N2, Endomethasone, SPAD). Methacrylate resin. Mineral trioxide aggregate (MTA). Silicone (ex.Lee Endo-Fill, Roeko Seal Automix, RoekoSeal, GuttaFlow). (Orstavik, 2005) and (Bergenholtz et al, 2010).
. 24
Review of Literatures
Gatewood (2007) listed properties of and criteria for an ideal sealer as in table (1.2): Table (1.2): Requirements of ideal root canal sealers (Gatewood (2007)) Properties
Criteria
Should be tacky when mixed to provide good adhesion between it and the canal wall when set.
The sealer should adhere to the obturating material, usually gutta percha, when placed in the canal, and should adhere to the canal wall with its irregularities to completely fill the canal space.
Should make a hermetic seal.
The core material itself does not provide an adhesive seal to the canal wall and to create and maintain a fluid-tight seal of the canal is a prime requirement of a sealer.
Should be radiopaque.
The sealer should contribute to the radiopacity of the root filling for visualization on radiographs and evaluation of obturation of lateral canals and apical ramifications.
Should not shrink upon setting.
Any shrinkage of the sealer would tend to create gaps at the dentin interface or within the core material, compromising he seal.
Should not stain tooth structure.
Components of sealer should not leach into dentin leading to coronal or cervical discoloration of the crown.
Should be bacteriostatic, or at least not encourage bacterial growth.
This property is desirable, but increasing the antibacterial qualities of a sealer also increases its toxicity to host tissues.
Should set slowly.
A sealer must have ample working time to allow for placement during obturation and adjustment in the case of immediate postspace preparation.
Should be insoluble in tissue fluids.
Stability of sealer when set is a prime factor in maintaining a hermetic seal over time. This is compromised if fluid contact causes dissolution of the sealer.
Should be tissue-tolerant.
Biocompatibility of the sealer promotes periradicular repair. Most sealers tend to be more tissue-toxic in the unset state and considerably less toxic when fully set.
25
Review of Literatures Should be soluble in a common solvent.
To allow for retreatment or post-space preparation, the sealer and the core material should be removable. This can be facilitated by using a solvent.
The use of a sealer cement in conjunction with a core filling material is recommended with most obturating techniques and gutta-percha has no bonding properties to dentine regardless of the filling technique employed, thus sealer cements create a union between the core material and the canal wall by filling any residual spaces, in addition sealer cements often have the ability to penetrate areas such as lateral canals and dentinal tubules and the penetration of sealer cements into dentinal tubules is considered to be a desirable outcome for a number of reasons: It will increase the interface between material and dentine thus improving the sealing ability and retention of the material may be improved by mechanical locking. Sealer cements within dentinal tubules may also entomb any residual bacteria within the tubules and the chemical components of sealer cements may exert an antibacterial effect that will be enhanced by closer approximation to the bacteria (Mamootil and Messer, 2007). Leakage along root fillings may increase or decrease with time and dissolution of sealer may result in more leakage whereas swelling of gutta-percha may result in diminished leakage (Juhasz et al, 2006).
1.4.1.3.1. AH26 sealer: Garg and Garg (2007)showed that it is an epoxy resin recommended by Shroeder in 1957 and epoxy resin characterized by the reactive epoxide ring and are polymerized by the breaking this ring, it consist of a yellow powder and viscous resin liquid and mixed to a thick creamy consistency and gave the following composition: Composition: 26
Review of Literatures
I.
Powder: Bismuth oxide 60%. Hexamethylene tetramine 25%. Silver powder 10%. Titanum Oxide 5%.
II.
Liquid: Bisphenol diglycidyl ether.
Bergenholtz et al (2010)showed that the setting reaction of AH26 takes about 1-2 days (at body temperature) and 5-7 days (at room temperature) and is a polymerization process during which formaldehyde is released, but the concentration is more than 300fold which is less than that of a formaldehyde releasing from ZnOE formulation, but it had good mechanical properties and adhesion/adaptation to dentin and AH26 is biologically active molecule with low toxicity that well tolerated by periapical tissue also it had good antimicrobial properties while its antimicrobial effect decreases with increased setting time but in comparison with ZnOE, calcium hydroxide and GIC sealers on the model of infected root dentin, AH26 showed the strongest antimicrobial effect and its probably due to the initial release of formaldehyde and regarding radiopacity its considered to be good (6.6 mm A1) and because silver in AH26 may lead to tooth discoloration due to formation of black silver sulfide, preparation are available without silver, and bisthmus oxide is added for radiopacity. Epoxy resin based AH26 is thought to be able to react with any exposed amino groups in collagen to form covalent bonds between the resin and collagen when the epoxide ring opens and AH26 root canal sealer, having the great adhesive strength is consistent with other adhesion studies (Cobankaraet al, 2006).
27
Review of Literatures
Mahajan and Kamra (2006) concluded in their study that root canal filled with cold lateral condensation technique using AH26 sealer showed least leakage using dye and stereomicroscope method compared with other group that filled with cold lateral condensation technique and AH Plus sealer or ZnOE sealers. Souza et al (2008) concluded in their study performed for root canals filled with cold gutta-percha cone using two leakage model which are fluid filtration and glucose penetration method that AH26 sealer showed less leakage compared with AH plus but leakaed most than Roeko Seal sealer. Neto et al (2007) concluded in the study of assessing leakage of four resin-based root canal sealer which are (AH26, AHPlus, EndoRez and expermintal MBP as sealer) by single cone obturation technique using fluid filtration method that after 60 days, AH26 sealer showed less leakage compared with EndoRez but more leakage than AHPlus and MBP sealer. Khedemat and Rezaefar (2006) concluded in their study that removal of smear layer can significantly improve the apical sealing ability of AH26 sealer using electrochemical microleakage evaluation. Khedemat and Rezaefar (2007) concluded in the comparative study of sealing ability of Dorifill, AH26 and Apexit sealer using electrochemical method that the best seal was obtained using Dorifill and AH26 sealers and the poorest result was observed in Apexit.
1.4.1.3.2. Endofill sealer: Souza et al (2009) showed that Endofill sealer is a zinc oxide eugenol sealer having pH of 6.9 after 24 hour setting and gave following compositions: Composition: I.
Powder:
28
Review of Literatures
Zinc oxide, hydrogenatedresin, bismuth subcarbonate, bariumsulphate, sodium borate. II.
Liquid: Eugenol and almond oil.
Zinc oxide eugenol-based sealers have had their use standardized in endodontic over time and they are the most widely known and clinically employed root canal sealers and have been used as controls in several in vitro investigations for comparison to other endodontic sealers and previous studies have reported that zinc oxide eugenol based sealers have poor adhesive properties to dentin and is highly permeable (Dultra et al, 2006). Endofill has desirable physicochemical properties; however, if it accidentally comes in contact with periapical tissues, it will provoke a chronic inflammatory response and it had low resistance to bacterial leakage when compared with Polifil, Acroseal, Epiphany and AHPlus and this result could be explained by Endofill‟s characteristic of suffering solubility and a high loss of dimensional change, solubility and disintegration and the dissolution of Endofill seemed to start at the first moment of setting time and continued up to the sixth month that allowed bacterial leakage (Pinheiro et al, 2009). Bains et al (2007) showed that the photomicrographs using SEM were evaluated for the dentin-sealer-core material interface and found that the photomicrographs of the gutta-percha and Endofill sealer show a uniform gap between the sealer and dentin, while it bonded satisfactorily with the gutta-percha and explained reason for low sealing ability of zinc oxide-eugenol is the sudden setting of this material (transition from paste to solid mass) which may be responsible for debonding from dentinal walls or cohesive fracture caused by shrinkage setting stresses, which may explain the higher leakage.
29
Review of Literatures
Kopper et al (2006) concluded in their study that after 45 days of exposure to the oral environment, the endodontic sealers (Endofill and AHPlus) tested were not able to keep the root canal impermeable and prevent coronal dye leakage and he endodontic sealer, Endofill, after 90 days of exposure to the oral environment, presented lower sealing ability compared to the 45-day period and with AH Plus at both periods using dye leakage and stereomicroscope.
1.4.2. Root canal obturation techniques: Successful root canal treatment is critically dependent on the thorough cleaning and shaping of the root canal space (in order to control the pulp space infection), and on the tridimensional filling of the entire endodontic space with an inert, long time stable root canal core materials (Nica et al, 2011). Whitworth (2005)describe a spectrum of filling methods (Fig. 1.6) ranging from paste-only fills, through pastes with single cones of rigid or semi-rigid material, to cold compaction of core material and finally, warm compaction of core material with sealer paste and it is likely that most accounts have assumed the materials involved to be traditional sealer cements (such as zinc oxide eugenol pastes) in combination with metallic or gutta-percha cones and sealer cements are usually regarded as the critical, seal-forming „gasket‟ of the root canal filling, but paradoxically, as the weak link of the system whose volume should be minimized by core compaction.
30
Review of Literatures
Fig. (1.6): Classic spectrum of filling techniques, emphasizing the desirability of minimum sealer volume, from (a) pastes only (least desirable); through (b) single cones with
paste,
and
(c)
cold
lateral
compaction(Whitworth, 2005). 31
condensation,
to
(d)
thermoplastic
Review of Literatures
The root canal system should be sealed apically, coronally, and laterally and maintenance of adequate obturation is of critical importance for prevention of bacterial microleakage and the integrity of the apical seal is proportional to the amount of endodontic filling material (Rahimi et al, 2010). Hargreaves & Cohen (2011) explained that to date little evidence exists to support one method of obturation as being superior to another and the influence of treatment technique on success/failure has yet to be determined and method of obturation technique can listed as follow: Cold lateral compaction. Warm vertical compaction. Warm lateral compaction. System B continuous wave condensation technique. Sectional compaction technique. Thermoplastic injection techniques: Obtura III. Ultrafill 3D. Calamus. Elements. HotShot. GuttaFlow. Ultrasonic plasticizing. Solid core obturation technique: Single cone obturation technique. Silver point obturation. Carrier-Based Gutta-Percha:
32
Review of Literatures
Thermafil, Profile GT Obturator, GT Series X Obturator, and ProTaper Universal Obturators. Successfil. SimpliFill. McSpadden compaction of gutta-percha. Chemically softened gutta-percha (Solvent techniques): Chloroform. Halothane. Eucalyptol. Pastes. Immediate obturation (Apical barrier).
1.4.2.1. Cold lateral condensation technique: The various proposed methods for obturation of the radicular space can be divided into two basic groups: cold lateral condensation and warm vertical condensation and lateral condensation of gutta-percha filling material is the most commonly taught and practiced filling technique, and is the standard procedure against which all others are evaluated ,although many variations of the technique have been proposed in terms of master cone design, spreader design, application and accessory cone selection, there is no clear consensus of which is ideal and lateral condensation is a safe and cost-effective technique, but it is time-consuming and lacks homogeneity and adaptation to the canal walls and moreover, a common criticism leveled at the technique is that it may induce vertical root fractures(Mahera et al, 2009). Filho et al (2008) stated that the lateral condensation is the most frequently used technique to prevent overfilling and concluded that less overfilling using lateral
33
Review of Literatures
condensation is obtained comparing to thermoplastic techniques, such as Thermafil or backfilling. Devcic et al (2005) showed among disadvantage of cold lateral condensation technique are relatively lengthy procedure and the radiographic appearance of the canal filling homogeneity is better than it is in reality and thinner gutta-percha accessory cones because of their flexibility, create angulations to the main cone causing microspaces of entrapped air between the main and accessory cones and cold lateral condensation technique is simple and effective, although other techniques have been developed with a tendency to use warmed and softened gutta-percha to achieve better contact with canal walls. Leonardo et al (2009) explained cold lateral condensation technique (Conventional technique) as it is the compaction of successive gutta-percha cones associated with endodontic cement with the aid of spacers filling the interior of the root canal, however some researchers state that it does not provide three-dimensional obturation, causing excessive stress and excessive expenditure of material. Use of a master cone with a larger taper increases the amount of gutta-percha within the canal, reducing the amount of sealant between accessory cones, which is desirable to improve the three-dimensional filling of the canal so use of .06 gutta-percha cone reduces the number of accessory points and the obturation time compared with use of .02 gutta-percha cones with cold lateral condensation, however use of a gutta-percha cone matched to the taper of the preparation does not allow spreader penetration to within 1 mm of the working length so the penetration depth of the spreader with cold lateral condensation affects the quality of the apical seal(Heredia et al, 2007). The root canal system often possesses a complex anatomy, including fins, culs-desac, isthmi, ramification, and other irregularities and it has been claimed that many of these area difficult to fill by using conventional technique such as cold lateral condensation technique and thermoplasticized gutta-percha technique reproduce internal 34
Review of Literatures
root canal anatomy better than lateral condensation, including a better dentin wall adaptation, and usually provide a more homogenous mass of gutta-percha when compared to lateral condensation and both the Thermafil plus technique and the continuous wave of condensation technique (system B) are two thermoplasticized guttapercha obturation techniques that claims to possess these advantage over the cold lateral condensation technique(Kontakiotis et al, 2007). Anbu et al (2009) concluded in their study which done to analyses volumetrically using spiral computed tomography (SCT) the efficacy of various techniques to fill root canals that voids were seen in all the root fillings and the greatest percentage of obturated volume was obtained with System B and Thermafil techniques; lateral compaction, produced the least percentage of obturated volume and spiral computed tomography appears to be a valuable tool to locate voids and to assess the efficacy of obturation at various levels. Dadresanfar et al (2010) concluded in their study that compared the sealing ability of the lateral condensation technique and the Bee-Fill system after canal preparation by the Mtwo rotary system using dye penetration that the Bee-Fill thermoplasticized injection technique and the lateral condensation technique resulted in similar apical leakage; thus, the Bee-Fill system appears acceptable for obturation. Farea et al (2010) concluded in their study that evaluated in vitro the apical sealing ability of cold lateral and system B root filling techniques using dye penetration that system B continuous wave condensation technique created a better apical seal than conventional cold lateral condensation technique. Ferreira et al (2011) concluded in their study using cross sectional study by software image analysis
to determine gutta-percha‟s root canal filling capacity through
three different filling techniques that among the tested root canal filling techniques, Tagger‟s hybrid is the one presenting the most gutta-percha‟s root canal filling capacity, followed by hydraulic compression and lateral condensation technique. 35
Review of Literatures
Xu et al (2007) concluded in their study that evaluated the sealing ability of four obturation techniques by using a glucose leakage test that warm vertical compaction, Thermafil and the E & Q which is new method used in same manner as the system B showed better sealing result than cold lateral condensation of gutta-percha at extended observation periods. Von Fraunhofer et al (2005) concluded in their study that evaluated the effect of two canal preparation methods (standardized technique and Ultradent Endo-Eze system) obturated by conventional cold lateral condensation technique and Endo-Eze canal obturation (AET procedure) using electrochemical leakage test that teeth filled with Endo-Eze system showed better sealing ability and more resistance to leakage than teeth filled with conventional technique.
1.4.2.2. Single cone obturation technique: Rotary Ni–Ti instruments employing the crown-down technique have emerged during the last decade as a possibly superior option to hand instruments and they appear to provide a more uniform root canal shape with a predictable taper in the apical region whilst retaining the original shape and patency of the canal and the use of Ni–Ti rotary instruments led to the development of greater taper standardized gutta-percha cones in order to match more closely the prepared shape of the canal (Romania et al, 2009). Single-cone obturations came in the 1960s with the development of ISO standardization for endodontic instruments and filling points and after reaming a circular, stop preparation in the apical 2 mm of the canal, a single gutta-percha, silver, sectional silver or titanium point was selected to fit with „tug-back‟ to demonstrate inlay-like snugness of fit and the cone was then cemented in place with a thin and uniform layer of traditional sealer, at least in the apical part of the canal and thus the advent of nickel titanium makes predictably centered preparations more realistic than
36
Review of Literatures
ever in curved canals and may make accurate apical cone fit a possibility in many cases as shown in fig. (1.7) (Whitworth (2005)).
.
Fig. (1.7): Matched, ergonomic shaping files and filling cones may inadvertently promote single cone filling techniques (Whitworth (2005)).
Alshehri (2010) showed that the single-matched, taper-sized cone technique has many advantages, including: Safe coronal extrusion of excess cement with mini - mall extrusion of sealer in the apical direction. A uniform mass of gutta-percha with less sealer at the canal wall interface and within the filling mass. A higher percentage of sealer-coated canals and a better sealer distribution. Significantly less implementation time. Ease of learning. Elimination of lateral stresses during obturation that may result in overfills and root fractures. 37
Review of Literatures
Higher quality obturation compared with other methods. No potential risk of tissue damage due to an increase in root surface temperature. no potential for obturation material shrinkage; and Lower cost. The single-cone technique consists of a single gutta-percha cone filled at room temperature with sealer layer thicknesses that vary; depending on the adaptation of the single cone to the walls of the canal and single-cone obturations have not been well regarded because of the use of large amounts of sealer and porosities in large volumes of sealer, setting contraction and dissolution of the sealer are the main disadvantages of this technique thus the poor seal and success of the material because of shrinkage after setting is a significant problem (Inan et al, 2009). Zhang et al (2009) stated that thin layers of sealer are preferred in modern endodontic, because the sealer might shrink during setting and dissolve over time, producing leakage and in the single-cone technique, the volume of sealer is high relative to the volume of the cone and this ratio promotes void formation and reduces seal quality and thus volume of the sealer used in the single-cone technique was minimized because gutta-percha cones were calibrated to the preparation. Tasdemir et al (2009) concluded in their study that determined the percent guttapercha-filled area in the apical third of root canals after filling with 2 different root filling techniques using cross-sectional study of the prepared canal from transverse sections obtained at several levels of the filled root and the ratio between these 2 values can be expressed as a percentage, the magnitude of which shows how much of the residual space is available to sealer or voids and the smaller the ratio, the higher the quality of the filling and found that the single-cone technique with tapered gutta-percha cones may yield better filling (measured as the percent gutta-percha-filled area) than the lateral condensation technique, at a level 2 mm from the apex.
38
Review of Literatures
Mahera et al (2009) showed that after one month from storage of specimens and using fluid filtration method to compare the apical microleakage of roots filled with system B, single-cone technique or lateral condensation that the single-cone technique leaked significantly more than the specimens filled with system B or lateral condensation. Yucel and Ciftci (2006) concluded in their study that compared bacterial penetration following obturation wit system B, lateral compaction, thermafil, single proTaper guttapercha cone and laterally compacted ProTaper gutta-percha that system B and laterally compacted ProTaper gutta-percha prevent bacterial penetration of the root canal at 30 days and there was no difference among obturation technique at 60 days. Tasdemir et al (2009) concluded in their study that compared the sealing ability of tapered single cone technique, cold lateral condensation technique and warm vertical compaction technique instrumented with ProTaper and Mtwo rotary systems that filling with SC, LC, and WVC techniques in canals treated with ProTaper or Mtwo instruments showed similar levels of sealing efficacy.
1.4.2.3. Thermafill obturation technique: Thermafil is an endodontic obturator described by Johnson in 1978 and it consisting of a solid carrier coated with alpha-phase gutta-percha and after heat softening the guttapercha and inserting into the root canal, the carrier is sectioned and becomes incorporated into the gutta-percha and the carrier was originally made of metal, but plastic carriers are used in the current product (Thermafil Plus; Dentsply Tulsa Dental, Tulsa, OK) and Thermafil produces a higher percentage of the gutta-percha obturated canal area compared with lateral condensation and the System B
technique also
Thermafil shows apical seal better than lateral condensation (Hayakawa et al, 2010). Both cold lateral compaction and contemporary single cone techniques produce a mass of gutta-percha leaving space filled with sealer and thermoplasticized gutta-percha 39
Review of Literatures
techniques were introduced in order to improve the three dimensional filling of root canals and in the past years, different studies indicated warm gutta-percha techniques as a successful alternative to replicate the irregularities of root canal system and one of the pre-heated gutta-percha filling technique that is used with plastic carriers for the delivery of softened gutta-percha is (Thermafil Plus Endodontic Obturators)and radiographic evaluation of the material adaptation has shown that Thermafil obturators are better than lateral compaction (Kocak et al, 2008). Cantatore (2006) stated that Thermafil obturation system consist of Thermafil obturator, the Thermaprep oven, verifiers, Therma cut bur, post space drills and resin epoxy sealer such as (TopSeal or AH26 or AHPlus) and described its advantage and disadvantages as follow: Advantages of Thermafil obturation techniques: Three-dimensional obturation. Minimal taper and diameter of the prepared canal is required. The traditional Thermafil obturator requires ideal taper of the canal between 5% and 6% with a minimum apical diameter of 0.20mm and in general, canals prepared for Thermafil can be prepared more conservatively than those prepared for the System B technique. This is particularly useful in long, fine and curved roots. Is ideal for use in curved and long canals. Where there are intra canal obstructions, the high flow of Thermafil gutta-percha enables the filling material to bypass these obstructions. Disadvantages of Thermafil obturation techniques: Risk of extrusion of gutta-percha Preparation of post space and retreatment require more time than System B 40
Review of Literatures
Difficult to use in canals with bi- or tri-furcation or in teeth with multiple canals with canal openings in close proximity to each other, especially in a small pulp chamber or in the presence of open apices and severe external resorptions.
De-Deus et al (2006) concluded in their study that determined the percentage of gutta-percha filled area (PGFA) in the apical third of root canals when filled with either Thermafil, System B or lateral condensation through
microscopic analysis and
photomicrographs of each apical surface were taken at a magnification of 50* and through digital image analysis, the cross-sectional area of the canal and the gutta-percha was measured found that the coated carrier gutta-percha system Thermafil produced significantly higher PGFAs than lateral condensation and System B techniques. Gencoglu et al (2007) stated that the reduced ratio of sealer to gutta-percha may improve the long term seal provided by root canal fillings and endodontic sealers are soluble materials and the shrinkage may result in potential leakage pathways in root canal fillings and gross amounts of sealer may result in increasing amount of leakage and found after evaluated the sealer-gutta-percha ratio in Thermafil, Quick-Fill, Soft Core Microseal, System B and lateral condensation techniques, they found that Thermafill, JS Quick-Fill and Soft Core techniques had more gutta-percha content than Microseal, System B and lateral condensation techniques and they stated that higher sealer content might lead to higher leakage amounts and found in their study that Microseal and lateral condensation techniques showed higher leakage and Thermafil showed less mean leakage value. Stratul et al (2011) concluded in their study that evaluated the morphology of the root canal in its apical third and the capacity of the Thermafil System to reproduce the entire morphology of the cleaned and shaped root canal by ProTaper rotary root canal preparation using multiple images of successive sections were used to create a 3D 41
Review of Literatures
reconstruction of the apical anatomy of the tooth and found that the apical foramen is most often located at a distance between 0.5 and 3 mm from the centre of the tooth apex, with major impact on endodontic procedures and the complex morphology of the apical third of the root canal is satisfactory micro structurally replicated by the Thermafil system.
1.5. Assessment of the quality of root canal fillings: A variety of techniques have been used to evaluate the quality of root fillings including leakage (radioisotope, dye penetration, fluid filtration, bacterial leakage, glucose penetration, electrochemical method), radiographic comparisons, microscopic evaluations or cross-sections, clearing technique and Micro CT technique(Kececi et al, 2005) and (Anbu et al, 2010).
1.5.1. Microleakage studies: The main reason for endodontic treatment failure is usually microleakage and this phenomenon has also be described as marginal permeability, micro marginal leakage, fluid exchange, liquid diffusion, and capillary penetration and microleakage is the result of the fact that current conservative materials do not chemically bond to cavity walls to extent of forming a hermetic seal and lack of a hermetic seal at the interface means a gap that allows the seepage of oral fluids between the restoration and the prepared surface (Achiar and Subrata, 2008). Apical leakage refers to infiltration of the apical root segment by peptides and other molecules, which have the potential to support microbial metabolism in the filled root canal system, because microorganisms are the cause of apical periodontitis (Rechenberg et al, 2010). Gutta-percha combined with a sealer are often used to fill root canals and guttapercha is dimensionally stable whereas most sealers dissolve with the potential for an 42
Review of Literatures
increase in leakage along the root fillings over time and in general terms, gutta-percha compaction techniques are preferred because they maximize the volume of gutta-percha and result in a thin layer of sealer on the canal walls and later on reducing microleakage (Souza et al, 2009). A variety of materials and techniques have been developed to improve the quality of root canal obturations but however, none of these materials and techniques provides a leak-proof seal and the microleakage is a serious clinical problem because most dental materials exhibit varying degrees of microleakage and the most important prerequisites of endodontic are total debridement of the pulpal space, development of a fluid-tight seal at the apical foramen and total obliteration of the root canal, therefore leakage tests are a relevant way to evaluate the apical seal (Inan et al, 2009). A variety of laboratory-based experimental models are used to detect and measure leakage along root fillings, whilst dye leakage, fluid transport and bacterial penetration were the most frequently used, other methods such as radio-labeled, electromechanical tests and glucose penetration have also been described and these models check penetration of different tracers through the root canal, assuming it travels along the canal and reaches the apical region (Mahera et al, 2009). Shemesh et al, 2007 claimed that filtration, diffusion or electrical phenomena governed the outcome of leakage studies in the corresponding models and thus raised doubt on the relevancy of these findings; the size of the tracer might also influence the results as well as the potential of the tracer to react or affect the filling material itself, for example methylene blue, frequently used in dye leakage studies, might react with different filling materials and calcium hydroxide, making the results from some of these tests unreliable and a different problem with leakage tests might be that different leakage tracers could penetrate through root dentine and not through the canal and this claim is supported by the findings that dentinal tubules are permeable to bacteria, adhesive agents, cements, and fluids and furthermore, dentinal tubules are oriented perpendicular 43
Review of Literatures
to the root canal walls and the contact surface area may affect the seal provided by the filling material, as the smear layer is usually removed prior to obturation, the tubules might be open and allow the tracer used in leakage studies to penetrate through them.
1.5.1.1. Electrochemical microleakage assessment: Jacobson and von Fraunhofer (1976) first described the quantitative means of estimating apical sealing procedures by using an electrochemical technique and they noted that when the potassium chloride permeated the apical seal and reached a mild steel rod placed through the occlusal access opening, corrosion of the steel was established which provided a quantitative estimation of the apical leakage and in turn the efficacy of apical sealing procedures and it is a reliable technique for testing microleakage and offers the advantage in term of speed, accuracy, efficiency and obtaining quantitative measurements of the entire sample as well as their ability to perform longitudinal studies and helps to study and measure the leakage in a continuous time period, does not require destruction of the samples to obtain measurements as well as easy to compare and analyze and, is less liable for laboratory preparation mistakes (Kavitha, 2004). The electrochemical method was also used to compare its reliability with other technique such as autoradiography, dye penetration, fluid filtration and glucose penetration and recent study has demonstrated excellent correlation between electrochemical and dye leakage assessment methods and because of it is highly related to the property of electric transmission of restorative materials can lead to destruction of tooth structure also its dielectric property is changed with time due to the continuous setting reaction of the materials(Nguyen, 2008). Economides et al (1999) concluded in their study that examined the effect of smear layer on apical microleakage using AH26 and Roth 811 sealer assessed by electrochemical method and found that the removal of the smear layer improved the 44
Review of Literatures
quality of apical sealing when AH26 sealer was used and there is no statistically significant difference were detected with Roth 811, even though the mean microleakage values were lower in the group without smear layer. Von Fraunhofer et al (2000) concluded in their study that evaluated the effect of smear layer and canal instrumentation on leakage root filled with AH26 sealer and cold lateral condensation and thermoplasticized obturation technique
assessed by
electrochemical test and found that smear layer removal is beneficial to root canal sealing and obturation with thermoplasticized gutta-percha provides a superior seal whilst canal instrumentation with engine-driven NiTi files reduces the extent of microleakage in root canals. Pommel et al (2001) concluded in their study that compared three methods of evaluation of the apical seal which are fluid filtration, electrochemical method, and a dye penetration of root prepared with Profile device and filled with Thermafil, warm vertical condensation and the single cone technique and found that there are no correlation among the results obtained with the three methods of evaluation and also it found that root filled with Thermafil system exhibited more leakage resistance than warm vertical and single cone technique assessed by electrochemical method. Karagenc et al (2006) concluded in their study that compared four different microleakage tests for assessment of leakage which are dye leakage, electrochemical test, bacterial test and fluid filtration test of root filled with Thermafil and lateral condensation technique and found that there are poor correlation between various methods to evaluate hydraulic leakage and also found that root filled with Thermafil system exhibited more leakage resistance than lateral condensation technique assessed by electrochemical test method. Inan et al (2007) concluded in their study that compared the sealing ability of three different obturation techniques which are Thermafil, cold lateral condensation and system B using electrochemical evaluation and dye penetration and found in both 45
Review of Literatures
methods, the lowest mean leakage values were observed for Thermafil and the highest were observed for the cold lateral condensation groups. Modaresi et al (2007) concluded in their study that compared the apical leakage using dye penetration and electrochemical methods each successively used on the same teeth and found that there was no significant correlation among the result obtained with two methods. Kurtzman and von Fraunhofer (2009) concluded in their study that compared the leakage behavior of the Resilion-Epiphany self-etch adhesive and Resilion-Epiphany Resin Primer Sealer obturation system with that of gutta-percha with both AH26 and zinc oxide eugenol sealer using electrochemical methodology and found that the leakage behavior of all groups increased with time and teeth obturated with Resilion-Epiphany Resin Primer Sealer exhibited less leakage current over the other group.
46
Chapter Two Materials& Methods
Materials & Methods
2. Materials & Methods: 2.1. Instruments and Equipments: Straight hand piece (NSK, Belmont,Japan). Sectioning disk “diamond abrasive disc” (0.2 mm thickness) (Komet, Germany). Set of K file (ISO 15-40) (Dentsply, Switzerland). Set of K file (ISO 10) (Dentsply, Switzerland). Finger spreader size 35 (Quayle dental). Endodontic plugger (TDENT 1, Switzerland). Endodontic ruler-mini endo block (Maillefer/Dentsply, Switzerland). Cement spatula (ASA stainless steel 0903-2). Cement slab (Iran). GG drills size #2, #3 and #4 (Mani., Japan). (Fig. (2.1)). ProTaper rotary file system Sx, S1, S2, F1, F2, F3 and F4 (Dentsply Maillefer, CH1338 Ballailgues, Switzerland). (Fig. (2.5)B). X-SMART electric torque controlled rotary device (16:1 Gear reduction) (Dentsply Maillefer). (Fig. (2.4)A). Therma prep plus oven (Patents Pending) (Made in Holland). (Fig. 2.4)B). Turbine carbide fissure bur (DIA-Italy). Dappen dish. Tweezers (SMIL, China). Local anesthetic carpule with needle of 27 gauges. Disposable syringe & plastic syringe. (China). 47
Materials & Methods
Permanent marker (Roller-tip pen, 0.5). Lacron Carver (China). BIO-RAY Prox (hand held portable dental x-ray) (Korea) and digital x-ray system (Sopix, France). (fig. 2.6). Electrochemical leakage test circuit component: (Fig. (2.7)):( custom made): -Power source supply (20V DC) (B4191-Auxillary power supply module, Japan). -AVO meter (Victor-VC9801A, Japan). -100 Ohm standard resistor. -Platinum electrode (In Gold) (Japan). -Clamp holder. -Plastic container of 65cm ˟ 50cmsize (China). -PVC insulated copper wire (China).
2.2. Materials: Gutta-percha points (size: 15-40) (GAPADENT, Hamburg Germany). (Exp. date 042013) (Exp.date 12/2013) (Fig. (2.1). Absorbent paper points (size: 15-40) (GAPADENT, Hamburg Germany). (Exp.date 10-2013), (Exp.date 12/2013) (Fig. (2.1). ProTaper gutta-percha points F4 (Dentsply Maillefer, CH-1338 Ballailgues, Switzerland), (Exp. date 06-2014). (Fig. (2.5)A).
48
Materials & Methods
ProTaper paper points F4 (Dentsply Maillefer, CH-1338 Ballailgues, Switzerland), (Exp.date 01-2015). (Fig. (2.5)A). ProTaper thermafill obturators size F4 (Dentsply Maillefer, CH-1338 Ballailgues, Switzerland), (Exp.date 08-2015). (Fig. (2.5)A). Two types of endodontic sealers: (Fig. (2.3)): -Endofill, zinc oxide eugenol-based sealer (PD, Switzerland). (Exp. date 05-2013). -AH26, epoxy resin sealer (DETERY, Dentsply), (Exp. date 04-2015). Solution used in the study: (Fig. 2.2): -EDTA solution 17% (PD, Switzerland), (Exp. date 04-2014). -Sodium hypochlorite solution 5.25% (Chlorox, commercial household, Saudia Arabia, Expirate date 12.2011). -NaCl 0.9% (Normal saline, Iran). -Distlled water (Al-Mansour Co., Iraq). -PrimeDent-RC Cream™.(Lubricant), (Exp. date 07-2012). Nail varnish (PourTori, S.A.R). Sticky wax (Cavex Set Up Regular, Netherland). Silicone adhesive (China). Disposable gloves (Malaysia). Rubber cup (JIC-Full dent, S.A Switzerland). Pumice (Quayle Dental, England).
49
Materials & Methods
Fig. (2.1): The materials and instruments used in the study.
Fig. (2.2): The solutions and syringes used in the study.
50
Materials & Methods
Fig. (2.3): Endofill and AH26 sealer used in the study.
Fig. (2.4): A:
A 1 1 Electronic controlled gear reduction 1 1 Thermaprep plus oven. 1 1
1
51
B
rotary device. B:
Materials & Methods
A 1 1 1 1 Fig. (2.5): A: ProTaper obturator, paper point and gutta-percha. B: 1 1 file (Sx, S1, S2, F1, F2, F3 and F4). ProTaper cleaning and shaping
1
Fig. (2.6): Bio-Ray Prox and digital sensor x-ray. 52
B
Materials & Methods
A 1 1 1 1 1 1
B
1
D C 1 1 Fig. (2.7): Electrochemical leakage1 test circuit component: A: Platinum 1 counter electrode. B: Standard resistor (100) Ohm. C: AVO meter. D: 1 1 of 20 V DC. Power supply
1 53
Materials & Methods
2.3. Methodology: 2.3.1. Sample selection Sixty extracted, single-rooted, closed apices, sound intact and straight canals human teeth were selected. Teeth were cleaned of extraneous tissue and calculus by pumice and rubber cup and then rinsed and stored in 0.9% saline solution at room temperature (Tasdemir et al, 2009). The anatomical crowns were removed at the cemento-enamel junction with a water-cooled diamond disc and root lengths were adjusted to approximately 16mm as shown in fig. (2.8).
Fig. (2.8): Tooth sectioning at cemento-enamal junction to average length of 16mm.
A fissure diamond bur was used to gain a straight-line entry to the root canal and after removal of the pulp tissue by using a barbed broach, a size 10 K-file was introduced into the root canal until the tip just visible at the major apical foramen. The working length determined by subtracting 1 mm from this length. Apical patency 54
Materials & Methods
confirmed by inserting a size 15 K-file through the apical foramen before and after the root canal preparation (Yucel and Ciftci, 2006).
2.3.2. Root canal instrumentation The root canals were prepared to the working length with ProTaper rotary nickel titanium instruments according to the manufacturer‟s instructions and all of the instruments used in a 16:1 gear reduction handpiece powered by a torque-controlled electric motor of 5:2 at a consistent rotation of 350 rpm and lubricant (PrimeDent,Root canal Cream™) was used throughout the cleaning and shaping of the root canal and the shapers (S1, S2, and SX), use in a brushing action and S1 advanced to resistance, but no more than two-thirds of the canal depth and then SX file introduced until resistance will be encountered and this will be followed by the reintroduction of the S1 file to the full working length and the other files then inserted to the full working length in the sequence S2, F1, F2, F3 and F4 to achieve #40 for the apical preparation and the finishers (F1-F4) were used with in-and-out action and 6 sets of ProTaper were used in the present study to prevent cyclic fatigue then each canal was irrigated with 2 ml freshly prepared5.25% NaOCl, using a syringe and a 27-gauge needle between each file and apical patency checked with a size 15K-file between each instrument and after preparation, the canals irrigated with 5.25 mL NaOCl followed by 5 mL 17% EDTA (PH 7.7) for 1 minute to remove the smear layer. Finally, the specimens irrigated with 10 ml distilled water to avoid the prolonged effect of the EDTA and NaOCl solutions. The canals subsequently dried with paper points and can be summarized the technique of rotary ProTaper nickel titanium preparation in fig. (2.9)(Ruddle, 2005) and (Tasdemir et al, 2009).
55
Materials & Methods
Fig. (2.9): The ProTaper shaping technique. The ProTaper sequence is always the same regardless of the length, diameter or curvature of the canal (Ruddle, 2005).
2.3.3. Sample grouping: After preparations, all root canals were randomly divided into four experimental groups (n=10) and 2 control (positive and negative) groups (n=5) as shown in fig. (2.10).
56
Materials & Methods
Main Group 60
Extracted teeth
Group A 20 roots obturated with CLC
Group A 1 10 roots obturated with CLC + Endofill
Group A 2 10 roots obturated with CLC+ AH26
Group B 20 roots obturated with Single Cone
Group B 1 10 roots obturated with Single Cone +AH26
Group B 2 10 roots obturated with Single Cone +Endofill
Group C 10 roots obturated with thermafill
Group C 10 roots obturated with thermafill+AH26
Fig. (2.10): Sample grouping. 57
Control Group 10 roots
Positive group
Negative group
5 roots
5 roots
Materials & Methods
2.3.4. Obturation of canals: Group A1: the canals were obturated with Gutta-percha and Endofill (a zinc oxide eugenol sealer) by a cold lateral condensation technique. A standard size 40 gutta-percha master cone fitted to the working length and exhibited a “tug back” sensation then the sealer mixed according to the manufacturer‟s instructions and introduced into the canal by using a size 35 K-file operated by hand in a counterclockwise rotation and a size 40 master gutta-percha cone lightly coated with sealer and then placed to the full working length and lateral compaction will be performed using a size 35 finger spreader to a level approximately 1 mm short of the working length and size 20 accessory cones coated with sealer and inserted into the canal until the spreader would not penetrate more than 2 to 3 mm then the excess point removed with a hot plugger and the filling compacted vertically with a warm instrument (Xu et al, 2005 and Xu et al, 2007 ). Group A2: the canals were obturated with Gutta-percha and AH26 sealer (an epoxy resin based sealer) by cold lateral condensation technique. AH26 sealer mixed according to the manufacturer‟s guidelines in an approximately 2:1 powder to liquid ratio at room temperature; a size 35 file used to introduce the AH-26 sealer to the working length with counter-clockwise rotation and then obturated teeth with same manner as described in group A1. Group B1:canals were obturated using #40 Single-cone ProTaper gutta-percha (F4) with AH26 sealer and theF4 gutta-percha prefitted in the root canal at the working length and then checked for tug-back the Endofill sealer applied into the root canal using a size 35 K-file operated by hand in a counter clockwise rotation and the apical part of the F4 gutta-percha cone coated with sealer, and then introduced into the root canal slowly until the working length reached and after obturation, excess gutta-percha cone cut off coronally with a hot plugger (Yilmaz et al, 2009). 58
Materials & Methods
Group B2: canals were obturated using #40 Single-cone ProTaper gutta-percha (F4) with Endofill sealer with same manner as described in group B1. Group C: canals were filled using ((F4) ProTaper Thermafill obturator with plastic core and AH26 sealer. A thin layer of sealer introduced into the root canal using a size 35 K-file operated by hand in a counterclockwise rotation, avoiding apical pooling and the preheated Thermafil obturator then inserted into the root canal to the apical stop (0.5 mm short of working length) according to manufacturer‟s instructions in one steady motion and after cooling, the excess gutta-percha and handle removed at the orifice by using a low-speed inverted-cone bur and finally, any gutta-percha compacted vertically with a hot plugger toward the orifice and in this study used only resin sealer with Thermafill which provides a superior seal with an epoxy resin sealer (Yucel and Ciftci, 2006) and (Gopikrishna and Parameswaren, 2006). After obturation of all roots was completed, all specimens were stored in incubator at 37C° for 7 days.
Positive and negative control groups: Ten teeth were instrumented and irrigated as in other groups but not obturated with insertion of PVC copper wire into inner surface of roots and fixed in a place with sticky wax and the root surfaces of five teeth entirely covered with two coats of nail varnish and served as negative controls while the other five teeth covered with two coats of nail varnish except the apical 2-3 mm and served as positive controls (Inan et al, 2007).
2.3.5. Radiographic Evaluation of Root Canal Obturation: After obturation, radiographs of all specimens taken were in bucco-lingual and mesiodistal directions by (Bio-Ray Prox and digital sensor x-ray) to evaluate the quality of the root canal filling with regard to homogeneity and apical extension as shown in fig. (2.10). 59
Materials & Methods
B
A 1 1 1 1 1 1
1
C
D
E
Fig. (2.11): Samples of radiographic evaluation of root canal obturation. A: CLC+Endofill. B: CLC+AH26. C: Single Cone+AH26. D: Single Cone+Endofill.E: Thermafill+AH26. 60
Materials & Methods
2.3.6. Leakage assessment by electrochemical method: The gutta-percha at the root canal orifice about (5 mm) were removed leaving about 10mm in canal by hot plugger for groups that obturated with gutta-percha points and
#2,#3 and #4 Gates-Glidden burs for groups that obturated with Thermafill
obturator to fit the electrical wire. The test methodology required placing of a PVC covered copper wire with an exposed end (that is, stripped of the PVC insulation at the terminal end) of 10 cm length after cutting with cutter to fit the sharpe end of wire to remaining root canal fillin materials and radiograph had been taken to verify attachment of wire to remaining root canal filling materials as shown in fig. (2.12)(Hirai et al, 2010).
Copper wire
Root specimen Remaining root canal filling materials
Fig. (2.12): Radiographical assessment of attachment of wire to remaining root canal filling materials.
The wire held in place with sticky wax and all external surfaces of the teeth will be coated with three layers of nail varnish (each group by specific color for differentiation) to provide electrical insulation and prevent fluid penetration through the cementum and/or any accessory canals and the apex of the treated tooth root left patent 61
Materials & Methods
about (2-3mm) and care taken to ensure that no nail varnish deposited on the apex. (fig. fig. (2.13)). (Kurtzman and von Fraunhofer, 2009).
A
B
C
Fig. (2.13): A: Tooth and wire sealed in place with sticky wax. B: Tooth with wire covered with three layer of nail varnish except of (2-3) apically left patent. C: A schematic diagram of tested tooth (von Fraunhofer and Jones, 2005).
Plastic container of 65* 50 cm was modified by researcher for mounting the roots with silicone through the bottom of the container after opening access inside the 62
Materials & Methods
container by carbide fissure bur according to size of each root with two additional opening one located medially for holding platinum counter electrode and other peripherally for immersion of 0.9% NaCl as shown in fig. (2.14). The length of roots of about 9mm submerged in 0.9% normal saline which represent as electrolyte solution (Karagenc et al, 2006).
Fig. (2.14): Roots are fixed with silicone on plastic container leaving about 9mm to be immersed in normal saline solution.
63
Materials & Methods
Platinum counter electrode was placed in the specimen container (only the last 10 mm immersed in solution) and (20-volt DC) current from a stable supply was connected between the platinum electrode immersed in the solution and the copper electrode wire in each specimen tooth and the current flow was determined by voltage drop across a standard resistor (100 Ω) placed within the electrical circuit as shown in ((fig.2.15) and fig. (2.16)) and leakage then detected when current passed in the external electrical circuit at room temperature; the start of the current indicated the onset of leakage while the magnitude of the current indicated the degree of leakage (Von Fraunhofer et al, 2005) and (Inan et al, 2007). Ammeter
Platinum Electrode
Fig. (2.15): A schematic diagram of the electrochemical leakage test circuit (Von Fraunhofer et al, 2005).
Each measurement lasted 3 to 5 min. and the current flow in the circuit was observed for 30 days at (0, 5, 10, 15, 20, 25 and 30 days). Between the readings the specimens stored in incubator at 37C° (von Fraunhofer and Kurtzman, 2008).
64
Materials & Methods
Fig. (2.16): Electrochemical leakage test circuit.
65
Materials & Methods
2.4 Data collection and statistical analysis: The statistical analysis methods used were in order to assess and analyze the result including:
A. Descriptive statistics: 1. Statistical tables. 2. Arithmetic mean. 3. Standard deviation (SD). 4. Graphical presentation of each group.
B. Interferential statistics: Theses have been used in order to accept or reject the statistically hypothesis and they include: 1. Student (t-test): from the comparison between two groups. 2. Analysis of variance (ANOVA) test to determine if there is a significant difference among the means of groups, where the F value was calculated and the level of significance P value was referred to a difference among the groups. 3. Post Hoc Test: is used for making multiple comparisons and to know the mean differences between groups, this includes LSD test.
The level of significance was calculated according to the P value and as follows: If P ˃0.05, this means that there is no significant difference (N.S). If P ˂ 0.05, this means that there is a significant difference (*). If P ˂ 0.01, this means that there is a highly significant difference (H.S).
66
Chapter Three Results
Results
3. Results: The results of this study are complied in tables (3.1 to 3.27), figures (3.1to 3.7), and appendices (I to VII). The electrochemical evaluation of leakage resistance of root canal obturated with Cold Lateral condensation technique, single sone technique and Thermafill obturation technique using Endofill and AH26 sealer was studied in this research work. The microleakage currents in (µA) had been taken for all groups at (0, 5, 10, 15, 20, 25 and 30) days baseline. All specimens showed a progressive increase in microleakage over time. No microleakage was observed in negative controls during the study. However, positive controls showed high microleakage values ranging from (6.1140 to 18.9020 µA) as shown in fig. (3.6). AH26 sealer exhibited lower microleakage values than Endofill sealer overall periods of study with all obturation techniques. The lowest microleakage values at all time were observed in Thermafill group, the highest values were observed in the single cone ProTaper group. The difference between these two groups was statistically significant (P ˂ 0.05). The cold lateral condensation group showed moderate microleakage values and the difference was also significant compared with either Thermafill or single cone group as shown in fig. (3.7). The following tables and graphs show the statistics, details and analysis of microleakage currents that related to different materials and techniques at different time periods.
67
Results
Table (3.1) Mean microleakage currents (µA) and standard deviation of all groups immediately at time of (0 day). The results was showed that positive group exhibted more microleakage currents followed by group B2 while group C showed least microleakage current. Groups
Mean
Std. deviation
A1
1.9930
0.17876
A2
1.4820
0.24073
B1
3.5200
0.38283
B2
4.0680
0.50994
C
0.9240
0.40814
Positive Control
6.1140
0.11149
Table (3.2) Analysis of variance (ANOVA) for microleakage currents at time of (0 day). Variance
Sum of squares
Df
Mean square
F
Sig.
Between Groups
589.370
6
98.228
727.019*
0.0001
Within Groups
7.161
53
0.135
Total
596.531
59
---------
68
Results
Table (3.3) Least Significant Difference (LSD) test for microleakage currents of all groups at time of (0 day). Groups
A2
B1
B2
C
7.925*
1.527*
2.075*
1.069*
Positive Negative
X¯
1.993
means different
4.121*
1.993*
SD
0.17876
Sig.
0.0001
0.0001
0.0001
0.0001
0.0001
0.0001
6.398*
5.850*
8.994*
3.804*
3.804*
1.482
means different
----
X¯ SD
0.24073
Sig.
----
0.0001
0.0001
0.0001
0.0001
0.0001
---
---
0.548*
2.596*
2.594*
3.520*
X¯
3.5200
means different
SD
0.38286
-----
-----
0.0001 ---
0.0001 3.144*
0.0001 2.046*
0.0001 4.068*
X¯
4.6682
Sig. means different
SD
0.50994
-----
-----
----
0.0001 ---
0.0001 5.190*
0.0001 .924*
X¯
0.9240
Sig. means different
SD
0.40814
-----
-----
-----
-----
0.0001 ---
0.0001 6.114*
X¯
6.1140
Sig. means different
SD
0.11149
-----
-----
-----
-----
-----
0.0001 ---
X¯
0.000
Sig. means different
SD
0.000
Sig.
---
---
---
---
---
---
A1
A2
B1
B2
C
Positive
Negative
*Significant at level ≤ 0.05
69
Results
Table (3.4) Mean microleakage currents (µA) and standard deviation of all groups at time of (5 days). The results was showed that positive group exhibted more microleakage currents followed by group B2 while group C showed least microleakage current.
Groups
Mean
Std. deviation
A1
2.9930
0.16214
A2
2.4570
0.12482
B1
4.7820
0.41635
B2
5.2810
0.62022
C
1.9700
0.40982
Positive Control
10.3160
0.27943
Table (3.5) Analysis of variance (ANOVA) for microleakage currents at time of (5 days). variance
Sum of squares
Df
Mean square
F
Sig.
Between Groups Within Groups Total
374.064 7.223
6 53
457.460*
0.0001
381.287
59
62.344 0.136 ---------
70
Results
Table (3.6) Least Significant Difference (LSD) test for microleakage currents of all groups at time of (5 days).
Groups
A2
B1
B2
C
Positive
Negative
0.536*
1.789*
2.288*
1.023*
7.323*
2.993*
Sig. means different
0.002 ----
0.0001
0.0001
0.0001
0.0001
0.0001
6.398*
5.850*
8.994*
3.804*
9.918*
Sig. means different
------
0.0001 ---
0.0001
0.0001
0.0001
0.0001
0.548*
2.596*
2.594*
3.520*
Sig. means different
-----
0.002 ---
0.0001
0.0001
0.0001
3.311*
5.035*
5.281*
Sig. means different
-----
0.0001 ---
0.0001
0.0001
8.346*
1.970*
Sig. means different
-----
0.0001 ---
0.0001
means different
X¯
2.993
SD
0.16214
X¯
2.457
SD
0.12482
X¯
4.7820
SD
0.41635
X¯
5.2810
SD
0.62022
X¯
1.9700
SD
0.40982
X¯
10.3160
SD
0.27943 0.000
Sig. means different
-----
-----
-----
-----
-----
0.0001 ---
0.000
Sig.
---
---
---
---
---
---
A1
A2
B1
B2
C
Positive
Negative
X¯ SD
-------------
--------
-----
10.316*
*Significant at level ≤ 0.05
71
Results
Table (3.7) Mean microleakage currents (µA) and standard deviation of all groups at time of (10 days). The results was showed that positive group exhibted more microleakage currents followed by group B2 while group C showed least microleakage current. Groups
Mean
Std. deviation
A1
6.9590
0.16855
A2
5.7370
0.19448
B1
7.3160
0.67154
B2
7.6580
1.10895
C
4.3440
0.49444
Positive Control
15.4020
0.81784
Table (3.8) Analysis of variance (ANOVA) for microleakage currents at time of (10 days). Variance
Sum of squares
Df
Mean square
F
Sig. p
Between Groups Within Groups Total
681.106 20.598 701.704
6 53 59
113.518 0.389 ---------
292.082*
0.0001
72
Results
Table (3.9) Least Significant Difference (LSD) test for microleakage currents of all groups at time of (10 days).
Groups A1
X¯
6.9590
SD 0.16855 A2
B1
X¯ 5.7370 SD 0.19448 X¯
7.3160
A2 means 1.222* different
B1 0.357
Sig. 0.0001 0.206 means ---1.579* different Sig. ---0.0001 means ----different Sig. -----
B2 0.699*
C
Positive Negative
2.615*
8.443*
6.959*
0.015 1.921*
0.0001 1.393*
0.0001 9.665*
0.0001 5.737*
0.0001 0.342 N.S 0.225
0.0001 2.972*
0.0001 8.086*
0.0001 7.316*
0.0001
0.0001
0.0001
SD 0.67154 B2
X¯
7.6580
means different Sig.
---
---
---
3.311*
5.035*
---
---
---
0.0001
0.0001
0.0001
means different Sig.
---
---
---
---
11.058*
4.344*
---
---
---
---
0.0001
0.0001
means different Sig. means different Sig.
---
---
---
---
---
15.402*
-----
-----
-----
-----
-----
0.0001 ---
---
---
---
---
---
---
5.281*
SD 1.10895 C
X¯
4.3440
SD 0.49444 Positive
Negative
X¯ 15.4020 SD 0.81784 X¯ SD
0.000 0.000
*Significant at level ≤ 0.05
73
Results
Table (3.10) Mean mcroleakage current (µA) and standard deviation of all groups at time of (15 days). The results was showed that positive group exhibted more microleakage currents followed by group B2 while group C showed least microleakage current. Groups
Mean
Std. deviation
A1
9.14
0.17882
A2
8.525
0.18757
B1
9.2910
0.68190
B2
9.6690
0.61124
C
7.2590
0.49709
Positive Control
18.4460
0.32478
Table (3.11) Analysis of variance (ANOVA) for microleakage currents at time of (15 days). variance Between Groups Within Groups Total
Sum of squares 887.891 10.798 898.689
Df
Mean square
F
Sig.
6 53 59
147.982 0.204 ---------
726.366*
0.0001
74
Results
Table (3.12) Least Significant Difference (LSD) test for microleakage currents of all groups at time of (15 days).
Groups
A1
A2
B1
X¯ SD
B1
B2
C
Positive
Negative
9.1400
means different
0.615*
0.151 N.S
0.529*
1.881*
9.306*
9.140*
0.17882 8.4250
Sig. means different Sig. means different Sig.
0.004 ----
0.458 0.766*
0.011 1.144*
0.0001 1.266*
0.0001 9.921*
0.0001 8.525*
------
0.0001 ---
0.0001 2.032*
0.0001 09.155*
0.0001 9.291*
---
---
0.0001 0.378 N.S 0.067
0.0001
0.0001
0.0001
means different Sig.
---
---
---
2.410*
8.777*
9.669*
---
---
---
0.0001
0.0001
0.0001
means different Sig. means different Sig. means different Sig.
---
---
--
---
11.187*
7.259*
-----
-----
-----
-----
0.0001 ---
0.0001 18.446*
-----
-----
-----
-----
-----
0.0001 ---
---
---
---
---
---
---
X¯ SD
A2
0.18757 9.2910
X¯ 0.68190 SD 9.6690
B2
X¯ 0.61124 SD 7.2590
C
X¯ SD
Positive
Negative
X¯ SD X¯ SD
0.49709 18.4460 0.32478 0.000 0.000
*Significant at level ≤ 0.05 75
Results
Table (3.13) Mean microleakage current (µA) and standard deviation of all groups at time of (20 days). The results was showed that positive group exhibted more microleakage currents followed by group B2 while group C showed least microleakage current.
Groups
Mean
Std. deviation
A1
9.3900
0.17576
A2
9.0940
0.16715
B1
10.5120
0.69737
B2
11.1830
0.62224
C
8.2220
0.48785
Positive Control
18.3140
0.22501
Table (3.14) Analysis of variance (ANOVA) for microleakage currents at time of (20 days). Variance Between Groups Within Groups Total
Sum of squares 895.833 10.735 906.568
Df
Mean square
F
Sig.
6 53 59
149.305 0.203 ---------
737.105*
0.0001
76
Results
Table (3.15) Least Significant Difference (LSD) test for microleakage currents of all groups at time of (20 days).
Groups
X¯
9.300
A1
A2
X¯ A2 SD X¯
means different Sig.
Positive Negative
1.793*
1.168*
8.924*
9.390*
0.0001
0.0001
0.0001
0.0001
0.0001
1.418*
2.089*
0.782*
9.220*
9.094*
0.0001 ---
0.0001
0.0001
0.0001
0.0001
0.671*
2.290*
7.8020*
10.512*
0.002 ---
0.000
0.000
0.000
2.961*
7.131*
11.183*
0.0001 ---
0.0001
0.0001
10.092*
8.222* 0.0001 18.314*
-------
0.16715 10.512
C
0.147
0.17575 9.0940
B2
means 0.2960 different N.S 1.122* Sig.
SD
B1
means different
---
Sig.
---
B1 SD
---
0.697 B2
X¯ SD
C
X¯ SD
Positive
X¯ SD
Negative
X¯ SD
11.1830
means different Sig.
-----
-----
---
0.62224 8.2220
means different Sig.
-----
-----
----
---
0.48785 18.314
means different Sig.
---
---
---
---
0.0001 ---
---
---
---
---
---
0.22501 0.000 0.000
means different Sig.
---
---
---
---
---
0.0001 ---
---
---
---
---
---
---
*Significant at level ≤ 0.05 77
Results
Table (3.16) Mean microleakage currents (µA) and standard deviation of all groups at time of (25 days). The results was showed that positive group exhibted more microleakage currents followed by group B2 while group C showed least microleakage current.
Groups
Mean
Std. deviation
A1
10.2990
.16849
A2
9.6530
.38887
B1
11.7210
.66527
B2
12.3210
.60775
C
8.7450
.48947
Positive Control
18.8260
.21161
Table (3.17) Analysis of variance (ANOVA) for microleakage currents at time of (25 days). Variance Between Groups Within Groups Total
Sum of squares 983.110 11.259 994.369
Df
Mean square
6 53 59
2163.86 0.212 ---------
78
F
Sig.
771.276* 0.0001
Results
Table (3.18) Least Significant Difference (LSD) test for microleakage currents of all groups at time of (25 days).
Groups A2
X¯ 10.2990
B1
B2
C
Positive
Negative
2.022*
1.554*
8.527*
10.299*
0.0001
0.0001
0.0001
2.068*
2.668*
0.908*
0.0001
0.0001
0.0001
0.0001
0.600*
2.976*
7.105*
11.721*
0.0001
0.0001
0.0001
3.576*
6.505*
12.321*
0.0001
0.0001
means different 0.646* 1.422*
A1 SD 0.16849 A2
B1
B2
Negative
----
0.0001
0.0001
X¯
9.6530
SD
0.3887
Sig.
----
0.0001
---
---
X¯ 11.7210
means different
SD 0.66527
Sig.
---
---
0.005
---
---
---
X¯ 12.3210
means different
0.60775
Sig.
---
---
---
0.0001
---
---
--
---
8.7450
means different
SD 0.48947
Sig.
---
---
---
---
0.0001
---
---
---
---
---
X¯ 18.8260
means different
SD 0.21161
Sig.
---
---
---
---
---
---
---
---
---
---
---
---
---
---
---
---
X¯
Positive
0.003
means different
SD C
Sig.
X¯
0.000
means different
SD
0.000
Sig.
9.173*
10.801*
9.653*
8.745* 0.0001 18.826*
*Significant at level ≤ 0.05 79
---
0.0001
Results
Table (3.19) Mean microleakage currents (µA) and standard deviation of all groups at time of (30 days). The results was showed that positive group exhibted more microleakage currents followed by group B2 while group C showed least microleakage current.
Groups
Mean
Std. deviation
A1
10.5980
0.17612
A2
9.9180
0.43011
B1
12.0930
0.63918
B2
12.8730
0.58409
C
8.8900
0.49067
Positive Control
18.9020
0.22477
Table (3.20) Analysis of variance (ANOVA) for microleakage currents at time of (30 days). Variance Between Groups Within Groups Total
Sum of squares 1014.181 11.060 1025.242
Df
Mean square
6 53 59
169.030 0.209 ---------
80
F
Sig.
809.969* 0.0001
Results
Table (3.21) Least Significant Difference (LSD) test for microleakage currents of all groups at time of (30 days).
A2
A1
Groups 10.5980 X¯
B1
B2
means 0.680* 1.495* 2.575* different 0.0001 0.0001
C
Positive Negative
1.708*
8.304*
10.598*
0.0001
0.0001
0.0001
0.17612
Sig.
0.002
9.9180
means different Sig.
----
2.175*
----
0.0001 0.0001
0.0001
0.0001
0.0001
means different Sig.
---
---
0.780*
3.203*
6.809*
12.093*
---
---
0.0001
0.0001
0.0001
0.0001
means different Sig.
---
---
---
3.983*
6.029*
12.873*
---
---
---
0.0001
0.0001
0.0001
means different Sig.
---
---
--
---
10.012* 8.890*
---
---
---
---
0.0001
0.0001
means different Sig. means different Sig.
---
---
---
---
---
18.902*
-----
-----
---
---
---
0.0001 ---
---
---
SD A2
X¯ 0.43011
2.955*
1.028
8.984*
9.918*
SD 12.0930 B1
X¯ 0.63918 SD 12.8730
B2
X¯ 0.58409 SD 8.8900
C
X¯ 0.49067 SD 18.9020
Positive
Negative
X¯ SD X¯ SD
0.22477 0.000 0.000
*Significant at level ≤ 0.05
81
---
---
---
---
---
---
---
Results
Table (3.22) Comparison of mean microleakage currents and standard deviation of cold lateral condensation technique with Endofill sealer (group A1) at time interval from (0 to 30 days). Time Interval 0 day 5 days
1 2
5 days 10 days 10 days 15 days 15 days 20 days 20 days 25 days 25 days 30 days
3 4 5 6
Mean microleakage currents (µA)
statistic Mean SD 1.993 0.17876 2.993 0.16214 2.993 6.9590 6.9590 9.1400 9.1400 9.300 9.300 25 days 25 days 10.5980
0.16214 0.16855 0.16855 0.17882 0.17882 0.17575 0.17575 10.9990 10.9990 0.17612
t 17.061*
p 0.0001
284.905*
0.0001
340.615*
0.0001
27.571*
0.0001
107.044*
0.0001
22.645*
0.0001
12 10 8 6
A1
4 2 0 0
5
10
15
20
25
30
Time (days)
Fig. (3.1) Graph representing electrochemical microleakage currents for test (group A1) started from (1.99 to 10.59 µA) from (0 to 30 days). 82
Results
Table (3.23) Comparison of mean microleakage currents and standard deviation of cold lateral condensation technique with AH26 sealer (group A2) at time interval from (0 to 30 days). Groups
statistic Mean SD
1
0 day 5 days
1.482 2.457
2
5 days 10 days 10 days 15 days 15 days 20 days 20 days 25 days 25 days 30 days
2.457 5.7370 5.7370 8.4250 8.4250 8.4250 8.4250 9.6530 9.6530 9.9180
3 4 5 6
t
p
0.24073 0.12482
15.108*
0.0001
0.12482 0.19448 0.19448 0.18757 0.18757 0.18757 0.18757 0.3887 0.3887 0.43011
66.675*
0.0001
630.460*
0.0001
17.166*
0.0001
5.382*
0.0001
8.078*
0.0001
Mean microleakage currents (µA)
12 10 8 6
A2
4 2 0 0
5
10
15
20
25
30
Time (days)
Fig. (3.2) Graph representing electrochemical microleakage currents for test (group A2) started from (1.48 to 9.91 µA) from (0 to 30 days).
83
Results
Table (3.24) Comparison of mean microleakage currents and standard deviation of single cone obturation technique with AH26 sealer (group B1) at time interval from (0 to 30 days).
1 2 3 4 5 6
Time Interval 0 day 5 days
statistic Mean SD 3.520 0.38286 4.8720 0.41635
5 days 10 days 10 days 15 days 15 days 20 days 20 days 25 days 25 days 30 days
4.8720 7.3160 7.3160 9.2910 9.2910 9.2910 9.2910 11.7210 11.7210 12.0930
0.41635 0.67154 0.67154 0.68190 0.68190 0.697 0.697 0.66527 0.66527 0.63918
t 18.795*
p 0.0001
23.910*
0.0001
66.389*
0.0001
61.315*
0.0001
31.873*
0.0001
31.000*
0.0001
12 10 8 B1 6 4 2
(µA)
Mean microleakage currents (µA)
14
0
0
5
10
15
20
25
30
Time (days)
Fig. (3.3) Graph representing electrochemical microleakage currents for test (group B1) started from (3.52 to 12.09 µA) from (0 to 30 days). 84
Results
Table (3.25) Comparison of mean microleakage currents and standard deviation of single cone obturation technique with Endofill sealer (group B2) at time interval from (0 to 30 days).
1 2 3 4 5 6
Time Interval 0 day 5 days
statistic Mean SD 4.6682 0.50994 5.2810 0.62022
5 days 10 days 10 days 15 days 15 days 20 days 20 days 25 days 25 days 30 days
5.2810 7.6580 7.6580 9.6690 9.6690 11.1830 11.1830 12.3210 12.3210 12.8730
0.62022 1.10895 1.10895 0.61124 0.61124 0.62224 0.62224 0.60775 0.60775 0.58409
t
p
9.779*
0.0001
8.875*
0.0001
7.600*
0.0001
118.707*
0.0001
48.629*
0.0001
8.165*
0.0001
12 10 8 B2 6 4 2 0
(µA)
Mean microleakage currents (µA)
14
0
5
10
15
20
25
30
Time (days)
Fig. (3.4) Graph representing electrochemical microleakage currents for test (group B2) started from (4.06 to 12.87 µA) from (0 to 30 days). 85
Results
Table (3.26) Comparison of mean microleakage currents and standard deviation of Thermafill obturation technique with AH26 sealer (group C) at time interval from (0 to 30 days).
1 2 3 4 5 6
Groups 0 day 5 days
statistic Mean SD 0.9240 0.40814 1.9700 o.40982
5 days 10 days 10 days 15 days 15 days 20 days 20 days 25 days 25 days 30 days
1.9700 4.3440 4.3440 7.2590 7.2590 8.220 8.220 8.7450 8.7450 8.8900
o.40982 0.49444 0.49444 0.49709 0.49709 0.48787 0.48787 0.48947 0.48947 0.49067
t 9.740*
p 0.0001
50.105*
0.0001
642.945*
0.0001
60.757*
0.0001
31.873*
0.0001
19.752*
0.0001
9 8 7 6 5
C
4 3 2
(µA)
Mean microleakage currents (µA)
10
1 0
0
5
10
15
20
25
30
Time (days)
Fig. (3.5) Graph representing electrochemical microleakage currents for test (group C) started from (0.92 to 8.89 µA) from (0 to 30 days). 86
Results
Table (3.27) Comparison of mean microleakage currents and standard deviation of positive controls group at time interval from (0 to 30 days). Time Interval 0 day 5 days
1 2
5 days 10 days 10 days 15 days 15 days 20 days 20 days 25 days 25 days 30 days
3 4 5 6
statistic Mean SD 6.1140 0.11149 10.3160 0.27941 10.3160 15.4020 15.4020 18.4460 18.4460 18.314 18.314 18.8260 18.8260 18.9020
0.27941 0.81784 0.81784 0.32478 0.32478 0.22501 0.22501 0.21161 0.21161 0.22477
t
p
34.891*
0.0001
18.303*
0.0001
12.141*
0.0001
1.437*
0.0001
44.230*
0.0001
2.216*
0.0001
20 18 16 14 12 10
Positive
8 6 4
(µA)
Mean microleakage currents (µA)
Positive
2 0
0
5
10
15
20
25
30
Time (days)
Fig. (3.6) Graph representing electrochemical microleakage currents for test positive controls group started from (6.11 to 18.90 µA) from (0 to 30 days). 87
Results
20 18
14
A1
12
A2 B1
10
B2
8
C Positive
6
(µA)
Mean microleakage currents (µA)
16
4 2 0
0
5
10
15
20
25
30
Time (days)
Fig. (3.7) Graph representing electrochemical microleakage currents for all test groups from (0 to 30 days).
88
Chapter Four Discussion
Discussion
4. Discussion: In this study the evaluation of the leakage resistance of root canal filled with AH26 and Endofill sealer were obturated with cold lateral condensation technique, single cone and Thermafill technique by electrochemical method was undertaken. In this study AH26 and Endofill sealer were used and AH26 showed more leakage resistance throughout the experimental time period for all obturation technique with significant difference when compared with Endofill sealer. Modaresi et al (2007) showed that all sealer undergo composition change, these changes occur upon setting and dissolution in fluids and dissolution of inorganic salts that used in sealer formulation may affect the ionic concentration, so accumulation of corrosion products with time or the filling material that undergo composition change, and released ionic compounds may affect the results of the electrochemical leakage determination. The finding of the present study came in agreement with those of (Mahajan and Kamra, 2006) who concluded that AH26 sealer showed less leakage behavior than AHplus and zinc oxide eugenol sealers using dye which can be explained to occur due to poor adhesive property of zinc oxide eugenol and good adhesive property of AH26 sealer. Also the cheat formed between two molecules of eugenol and one molecule of zinc oxide slowly hydrolyze in the presence of water to release eugenol. Another reason for the low sealing ability of zinc oxide-eugenol sealer is the sudden setting of this material (transition from paste to solid mass) which may be responsible for debonding from dentinal walls or cohesive fracture caused by shrinkage setting stresses, which may explain the higher leakage, while AH 26 an epoxy resin based sealer possess better sealing abilities compared to zinc oxide based sealers since the epoxy resin-based sealers are thought to be able to react with any exposed amino groups in collagen when the epoxide ring opens, thus having the higher bonding to dentin as shown in fig. (3.7) while the results of the present study disagree with (Kurtzman and von Fraunhofer, 2009) 89
Discussion
who showed that gutta-percha with zinc oxide-eugenol sealer exhibited more leakage resistance than gutta-percha with AH26 sealer by electrochemical method. In the present study, the roots filled with Thermafill technique exhibited more resistance to leakage with a significant difference to the cold lateral condensation technique and the single cone technique, while the cold lateral condensation technique showed significantly more leakage current than the Thermafill technique and less leakage current when compared with the single cone technique. The single cone technique showed significantly less leakage resistance compared to both Thermafill and cold lateral condensation technique as shown in fig. (3.7) and these results were supported by the study of (Pommel et al, 2001) who concluded that single cone technique had less leakage resistance compared with both Thermafill and vertical condensation technique and Thermafill showed less leakage behavior when using electrochemical method which was also suppoted by the study of (Karagenc et al, 2006) who concluded that Thermafill obturation technique exhibited more leakage resistance than cold lateral condensation technique using electrochemical leakage test and also with the study done by (Inan et al, 2007) who concluded that cold lateral condensation technique exhibited more leakage current than system B and thermafill obturation technique and also showed that Thermafill technique showed less leakage current compared with other group. The results of the present study disagree with (Inan et al, 2009) who showed that matched taper single cone exhibited less leakage behavior than Thermafill and cold lateral condensation technique using cross-section study. Neto et al (2007) showed that to seal the entire root canal system, the largest area has to be filled by gutta-percha and the root canal sealer is only an auxiliary used to promote better adhesion between root-canal walls and gutta-percha cones. Moreover, sealers are able to fill empty areas where gutta-percha was unable to fill. Romania et al, 2009 showed that this assumption is based on the fact that microleakage occurs along the inter surface between dentine and gutta-percha, dentine 90
Discussion
and sealer, or gutta-percha and sealer and also through the mass of the sealer due to setting contraction and time dependent dissolution. Inan et al, 2009 stated that “because of the widespread use of the rotary NiTi systems, manufacturers have produced gutta-percha cones that match the taper of canals prepared with these systems and this system have been introduced for simple, timeefficient obturation and can provide an effective seal even in curved root canal without the use of secondary cones”. On the other hand, porosities in large volumes of sealer, setting contraction and dissolution of the sealer were the main disadvantages of this technique and the poor seal and success of the material because of shrinkage after setting is a significant problem. Zhang et al (2009) showed that the explanation of single cone technique exhibited more leakage current which was due to the single-cone technique, the volume of sealer is relatively high to the volume of the cone and this ratio promotes void formation and reduces seal quality. Yucel and Ciftci (2006) stated that “the poor seal observed with single cone ProTaper gutta-percha may be related to the technique itself as the gutta-percha cone is not compacted but is only inserted to the working length in a large amount of sealer. The volume of sealer required for the single cone technique is larger than the volume necessary to complete a compaction technique and resulted in more leakage behavior”. Souza et al ( 2009) stated that “the rationale of the lateral compaction technique is to increase the GP ratio to sealer in the root canal aiming to potentially decrease the gaps that might occur due to sealer contraction or dissolution especially in the apical region while the higher leakage of lateral compaction might be due to several factors such as the size and taper of accessory cones chosen in all groups which was always smaller than the last spreader used to enable gutta-percha placement to the entire extension of the spreader track. However, big round-shape unfilled voids, resembling unfilled spreader tracks were frequently observed”. 91
Discussion
Xu et al (2007) showed that the addition of accessory gutta-percha cones could create a greater amount of voids between these cones. The cold, solid gutta-percha cones failed to adapt to the root canal wall and to each other easily, this technique produces many irregularities in the final mass of gutta-percha, and might not fill canal fins, culde-sacs and isthmuses. There is also inadequate dispersion of sealer, leaving voids in and around the gutta-percha cone. Farea et al (2010) reported that lateral condensation produces a less homogeneous obturation with poorer adaptation to the canal walls and these may possibly explain the fact that the root canals obturated with this technique numerically presented the highest mean apical infiltration. The Thermafil system, which has been chosen in this study for filling the root canal space, provided better results compared with the other obturation techniques. Stratul et al (2011) showed that Thermafill obturation technique provided less time consuming and was more convenient as an overall handling. It acts by inserting a homogenous mass of gutta-percha in the root canal, up to the working length, with a better core/sealer ratio than achieved by other techniques. Rajeswari et al (2005) reported that the Thermafil obturators proved a better seal than lateral condensation and the superior sealing ability of Thermafil can be attributed to its ability in filling main canal as well as lateral canals. DeDus et al (2007) claimed that the root canal sealer presented itself as a thin uniform layer distributed around the perimeter of the canal so voids found were very small and may be related to regions where cleaning and shaping were not efficient and debris could be the cause. The α-phase gutta-percha used presented peculiar characteristics, elevated radiopacity and excellent viscosity. The electrochemical method which was used in this study appears to be the only method testing leakage behavior that is able to provide a quantitative result, allowing the determination how much different materials leak. This methodology also removes viewer bias as seen with the other methodologies. Leakage is measured with an 92
Discussion
electronic apparatus and is not dependant on the viewer saying he or she could see a result (visible dye shown along the canal‟s length when the specimen was sectioned or turbidity seen on the media solution) (Kurtzman and von Fraunhofer, 2009). Khedmat and Rezaefar (2006) reported that among the advantages of electrochemical test method, it can be monitored continuously during the test while number of leaking teeth and degree of leakage can be determined. Also this method allows the measurement and comparison of leakage value in the same teeth during observation periods. Aydemir et al (2009) showed that by using this technique it is easily comparable and analyzed with ability to record the time when maximum leakage. Williamson et al (2009) reported that another methodological variation in leakage studies to consider is the influence of various times and conditions allotted for sealer set. Neto et al (2007) showed that the leakage along root fillings may increase or decrease during the course of a long period after filling. Dissolution of sealer and the smear-layer may result in a rise in leakage, whereas gutta-percha swelling may result in diminished leakage. Most sealers shrink during setting leaving unwanted voids and gradually dissolve and their sealing ability is also influenced by physical properties as viscosity, flow, setting time, and film thickness. Inan et al (2007) and Kazandag et al (2010) claimed that different observation periods, such as 1 week, 2 weeks, or longer, have been used for evaluation of microleakage of root canal fillings, because leakage increases by time regardless of the technique, a 3-week period was considered to be sufficient to make a comparison between techniques while (Khedmat and Rezaefer, 2006) was assessed the microleakage by electrochemical method for 30 days with 3-day intervals. In this study, the current flow in the circuit was observed for 30 days at base line of (0, 5, 10, 15, 20, 25 and 30 days) and it was concluded that all groups showed increase leakage behavior with time and these results were supported by the study of (Kurtzman and von Fraunhofer, 2009) who concluded that all materials will leak more 93
Discussion
over the initial period, and leakage behavior will plateau during the first 30 days then remain fairly consistent thereafter.
94
Chapter five Conclusions& Suggestions
Conclusions & Suggestions
5.1 Conclusions: Within the limitations of this in-vitro comparative study, the following conclusions can be withdrawn: 1. All roots filled with AH26 and Endofill sealer and obturated with Thermafill, cold lateral condensation and single cone techniques showed increased leakage behavior from (0 to 30 days). 2. AH26 sealer is significantly more leakage resistance compared with Endofill sealer for all obturation techniques at all different time interval using electrochemical method. 3. Thermafill obturation technique is significantly less leakage current (more leakage resistance according to Ohm‟s law using electrochemical method) than both cold lateral and single cone technique. 4. Cold lateral condensation technique showed moderate leakage and it‟s significantly less leakage behavior than single cone technique but significantly more leakage behavior than Thermafill obturation technique. 5. Single cone technique is significantly more leakage behavior than both of Thermafill and cold lateral condensation technique.
95
Conclusions & Suggestions
5.2 Suggestions: 1. Evaluation of the effect of root canal preparation by hand versus other rotary NiTi systems with using other type of sealers and obturation techniques on microleakage within endodontically treated teeth using electrochemical method. 2. Evaluation of the effect of presence and absence of smear layer with different instruments and obturation methods on microleakage of root canal filled teeth with electrochemical method. 3. Evaluation of correlation between electrochemical method and other method like dye penetration, bacterial penetration, fluid filtration and glucose penetration of apical leakage. 4. Evaluation
of
temporary
restorations
microleakage
by
means
of
electrochemical impedence measurements. 5. Evaluation of sealing ability of different retrograde filling materials using electrochemical test method. 6. Evaluation of immediate and delayed post space preparation on the apical seal of root canals obturated with different sealers and obturation techniques using electrochemical test method.
96
References
References
References: A Achiar KA and Subrata G. Infection and microleakage the caused of endodontic failure. Padjadjaran J Dent 2008; 20(1):61-7. Aguiar CM and Camara AC. Radiological evaluation of the morphological changes of
root canals shaped with ProTaper for hand use and the ProTaper and RaCe
rotary instruments. Aust Endod J 2008; 34: 115-19. Alshehri MA. Introduction of a novel obturation method: The single-matched, tapersized gutta-perch cone technique. International magazine of endodontology 2010; 6(3): 22-4. Anbu R, Nandini S and Velmurugan N. Volumetric analysis of root fillings using spiral computed tomography: an in vitro study. Int Endod J 2010; 43: 64–8. Aydemir H, Ceylan G, Tasdemir T, Kalyoncuoglu E and Isildak I. Effect of immediate and delayed post space preparation on the apical seal of root canals obturated with different sealers and techniques. J Appl Oral Sci 2009; 17(6): 605-10.
B Bains R, Chandra A, Tikku AP, Guoglu EK and Isildak I. An in vitro study to evaluate apical seal in roots filled with a thermoplastic ynthetic polymer based root canal filling material. Endodontology 2009; 21(1): 17-23.
97
References
Bansal P and Gupta H. Smear layer in endodontics-A review. Indian J Dent Sc 2009; 1 (2): 67-9. Bardsley S, Peters CI and Peters OA. The effect of three rotational speed settings on torque and apical force with vortex rotary instruments in vitro. J Endod2011; 37(6): 860-864. Beer R, Baumann MA and Kielbassa AM. Pocket atlas of endodontics. Stuttgart · New York. Thieme, 2006. Instrumentation using crown-down technique. P: 12425 Bernardes RA, Rocba EA, Duarte MAH, Vivan RR, de Moraes IG, Bramante AS and de Azevedo JR. Root canal area increase promoted by the EndoSequence and ProTaper systems: comparison by computed tomography. J Endod 2010; 36(7): 1179-82. Bergenholtz G, Bindslev PH and Reit. Text book of endodontology. Second edition. Wiley-Blackwell, 2010. CH 12. P: 193- 219. Bonsor SJ, Nichol R, Reid TMS and Pearson GJ. An alternative regimen for root canal Disinfection. BDJ 2006; 20 (2): 1-5. Brosco VH, Bernardineli N, Torres SA, Consolaro A, Bramante CM, Moraes IG and
Garcia
RB. Bacterial leakage in root canals obturated by different
techniques. Part 1: microbiologic evaluation.Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008; 105:48-53.
C Cantatore G. Root canal obturation and root integrity. Endodontic practice 2006; 2: 9-19. Cantatore G, Berutti E and CastellucciA.Missed anatomy: frequency and clinical impact. Endodontic Topics 2009, 15:3–31. 98
References
Castellucci A. Endodontics volume I and II. Il Tridente.2004. First edition. CH 19. P: 548-564. Cheung GSP, Bian Z, Shen Y, Peng B and Dravell BW. Comparison of defects in ProTaper hand-operated and engine-driven instruments after clinical use. Int Endod J 2007; 40:169–178. Cobankara FK, Orucoglu H and Belli S. Adhesion of a newly developed sealer to dentin: An in vitro study. Hacettepe Dishekimligi Fakultesi Dergisi 2006; 30 (1): 9-16.
D Dadresanfar B, Khalilak Z, Shiekholeslami M and Afshar S. Comparative study of the sealing ability of the lateral condensation technique and the BeeFill system after canal preparation by the Mtwo NiTi rotary system. J Oral Sc 2010; 52 (2): 281-85. De Deus G, Filho EDG, Magalhaes KM and Filho TC. A laboratory analysis of gutta-percha-filled area obtained using Thermafil, System B and lateral condensation. Int Endod J 2006; 39:378-83. De Deus G, Ferreria CMM, Filho EDG, Paciornilk S, Machado ACR and Filho TC. Comparison of the percentage of gutta-percha-filled area obtained by Thermafil and System B. Aust Endod J 2007; 33: 55–61. De Deus G, Souza EM, Marins JR, Reis C, Paciornik S and Zehnder M. Smear layer dissolution by peracetic acid of low concentration. Int Endod J2011; 44: 485-90. Depraet FJHW, De Bruyne MAA and De Moor RJG. The sealing ability of an epoxy resin root canal sealer after Nd:YAG laser irradiation of the root canal. Int Endod J 2005; 38:302-09.
99
References
Devcic N, Miltetic I, Ribaric SP and Segovic S. Microleakage of different root canal obturation techniques. Acta Stomatol Croat 2005; 39 (1): 81-4. Dultra F, BarrosoJM, Carrasco LD, Capelli A, Guerisoli DMZ and Pecora JD. Evaluation of apical microleakage of teeth sealed with four different root canal sealers. J Appl Oral Sci 2006; 14(5):341-5.
E Economides N, Liolios E, Kolokuris and Beltes P. Long term evaluation of the influence of smear layer removal on the sealing ability of different sealers. J Endod 1999; 25(2): 123-25.
F Farea M, Masudi S and Bakar WZW. Apical microleakage evaluation of system B compared with cold lateral technique: In vitro study. Aust Endod J 2010; 36: 48– 53. Ferreira CM, Gomes FD, Guimaraes NLSD, Ximenes TA, Caunto NSCP and Vitoraino MD. Analysis of gutta-percha‟s root canal filling capacity through three different obturation techniques. RSBO. 2011 Jan-Mar; 8(1):18-24. Filho JEG, Hopp RN, Bernabe PFE, Nery MJ, Filho JAO and Junior ED. Evaluation of apical infiltration after root canal disruption and obturation. J Appl Oral Sci. 2008; 16(5):345-9. Fiore PM. A dozen ways to prevent nickel-titanium rotary instrument fracture. J Am Dent Assoc 2007; 138: 196-201.
100
References
G Garg N and Garg A. Text book of Endodontic. Indian. First edition. Jaypee, 2007. P: 218-219. Gatewood RS.Endodontic materials. Dent Clin N Am 2007; 51: 695-712. Gencoglu N, Orucoglu H and Helvacioglu. Apical leakage of different gutta-percha techniques: Thermafill, Js Quick-Fill, Soft Core, Microseal, system B and lateral condensation with a computerized fluid filtration meter. Eur J Dent 2007; 1: 97103. Gopikrishna V and Parameswaren A. Coronal sealing ability of three sectional obturation techniques – SimpliFill, Thermafil and warm vertical compaction – compared with cold lateral condensation and post space preparation. Aust Endod J 2006; 32: 95–100. Gorduysus M, Tuncel B, Nagas E, Ergunay K, Yurdakul P, Erguven S, Torun OY and Gorduysus O. Antimicrobial effect of various endodontic irrigants on selected microorganisms. Clin Dent & Res 2011; 35(1): 41-46. Gu L, Kim JR, Ling J, Cboi KK, Pasbley DH and Tay FR. Review of contemporary irrigant agitation techniques and devices. J Endod 2009; 35(6): 791-804.
H Haapasalo M, Endal U, Zandi H and coil JM. Eradication of endodontic infection by instrumentation and irrigation solutions. Endodontic Topics 2005; 10:77–102. Haapasalo M, Shen Y, Qian W and Gao Y. Irrigation in endodontics. Dent Clin N Amer 2010; 54: 291-312. Hargreaves KM and Cohen S. Pathways of the pulp. St Louis Mosby, tenth edition. 2011. CH 9. P: 290-349. 101
References
Hayakawa T, Tomita F and Okiji T. Influence of the diameter and taper of root canals on the removal efficiency of Thermafil plus plastic carriers using ProTaper retreatment files. J Endod 2010; 36 (10): 1676-1678. Heredia MP, Gonzalez JC, Luque CMF and Rodriguez. Apical seal comparison of low-temperature thermoplasticized gutta-percha technique and lateral condensation with two different master cones. Med Oral Patol Oral Cir Bucal 2007; 12: 175-9. Hirai VHG, Neto UXD, Westphalen VPD, Perin CP, Carneiro E and Fariniuk LF. Comparative analysis of leakage in root canal fillings performed with guttapercha and Resilon cones with AH Plus and Epiphany sealers. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 109: 131-35. Hulsmann M, Peters OA and Dummer PMH. Mechanical preparation of root canals: shaping goals, techniques and means. Endodontic Topics 2005; 10:30– 76.
I Inan U, Aydemir H and Tasdemir T. Leakage evaluation of three different root canal obturation techniques using electrochemical evaluation and dye penetration evaluation methods. Aust Endod J 2007; 33: 18–22. Inan U, Aydin C, Tunca YM and Basak F.In vitro evaluation of matched-taper single-cone obturation with a fluid filtration method. Journal of Canadian Dental Associtation 2009; 75 (2): 123-26. Ingle JI.PDQ Endodontic. 5th ed, Hamilton, BC Decker Inc, Hamilton, 2005, CH 5. P: 111- 141. Ingle JI.Endodontics. 6th ed, Hamilton, BC Decker Inc, Hamilton, 2008, CH 27. P: 877- 973.
102
References
J Jacob S. Current trends in cleaning and shaping. Famdent Practical Dentistry Handbook 2006; 6 (4): 1-9. Juhasz A, Verdes E, Tokes L, Kobor A and Nagy CD.The influence of root canal shape on the sealing ability of two root canal sealers. Int Endod J 2006; 39: 282– 86.
K Karagenc B, Gencoglu N, Ersoy M, Cansever G, Enger and Kulekci G.A comparison of four different microleakage tests for assessment of leakage of root canal fillings. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006; 102: 110-3. Kavitha BN. An electrochemical evaluation of the sealing ability of three different retrograde filling materials- A comparative in vitro study. Rajiv Gandhi University of Health Sciences Karnataka, Bangalore. Msc thesis. 2004. Kazandag MK, Tanalp J, Bayrak OF, Sunay H and Bayirli G. Microleakage of various root filling systems by glucose filtration analysis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 109: 96-102. Kececi AD, Unal GC and Sen BH. Comparison of cold lateral compaction and continuous wave of obturation techniques following manual or rotary instrumentation. Int Endod J 2005; 38: 381-88. Khedmat S and Rezaefar M. Electrochemical evaluation of apical leakage of AH26 sealer after smear layer removal. Iranian Endod J 2006; 1(4): 141-144.
103
References
Khedmat S and Rezaefar M. Comparative study of sealing ability of three root canal sealers. J Dent Tehran Univ of Med Sc 2007; 20 (3): 184-92. Kocak MM, Er O, Saglam BC and Yaman S. Apical leakage of Epiphany root canal sealer combined with different master cones. European Journal of Dentistry 2008; 2: 91-95. Kontakiotis E, Chaniotis A and Georgopoulou M. Fluid filtration evaluation of 3 obturation technique. Quintessence Int 2007; 38 (7): 410-16. Kopper PMP, Vanni JR, Dellabona A, Figueredo JAPD and Porto S. In vivo evaluation of the sealing ability of two endodontic sealers in root canals exposed to the oral environment for 45 and 90 days. J Appl Oral Sci. 2006; 14(1):43-8. Kovac J and Kovac D. Effect of irrigation solutions in endodontic therapy. Bartisl Lek Listy 2011; 112 (7): 410-15. Kurtzman GM. Simplifying endodontics with EndoSequence rotary instrumentation. Canad Dent Assoc J 2007; 35 (9): 625-28. Kurtzman GM and von Fraunhofer JA. Leakage resistance of a self-etch sealercone obturation system. International Journal of Root Magazine 2009; 2: 24-26. Kurtzman GM and von Fraunhofer JA.The leakage resistance of endodontic fiber obturator. . International Journal of Root Magazine 2009; 1: 12-6.
L Leonardo MV, Goto EH, Torres CRG, Borges AB, Carvalho CAT and Barcellos DC. Assessment of the apical seal of root canals using different filling techniques. J Oral Sc 2009; 51 (4): 593-99. Low D. Root canal instrumentation with ProTaper universal instruments: revisited. ENDO (Lond Engl) 2010; 4(3): 201-206.
104
References
Lumley P, Tomson P, Pertot WJ and Machtou P. ProTaper-Hybrid technique. Dent Update 2008; 35: 110-16.
M Mahajan VA and Kamra AI. An in-vitro evaluation of apical sealing of three epoxy resin based commercial preparations. Endodontology 2006; 19 (1): 7-11. Mahera F, Economides N, Gogos C and Beltes P. Fluid-transport evaluation of lateral condensation, ProTaper gutta-percha and warm vertical condensation obturation techniques. Aust Endod J 2009; 35: 169-73. Mamootil K and Messer HH. Penetration of dentinal tubules by endodontic sealer cements in extracted teeth and in vivo. Int Endod J 2007; 40:873-81. McSpadden JT. Mastering Endodontic Instrumentation. Cloudland Institute. 2007. Miranzi BAS, Borges GA, Miranzi AJS, Menezes FHD, Miranzi MAS and Borges LH. Apical and cervical displacement produced by hand and enginedriven stainless steel and nickel-titanium instruments in simulated curved root canal. Braz J Oral Sci 2011; 10(2):136-39. Modaresi J, Davari A and Daneshkazemi A. Comparison of apical leakage patterns shown by two different methods. Pesquisa Brasileria em Odontopediatria e Clinica Integrada 2007; 7(2): 169-72. Mohammadi Z. Sodium hypochlorite in endodontic: an update review. Int Dent J 2008; 58: 329-41. Moretti AG, Pantoja CADMS, Moreira DM, Zaia AA and Almeida JFAD. Effect of the smear layer on the filling of artificial lateral canals and microleakage. Braz J Oral Sci 2011; 10(1):55-9.
105
References
N Neto UXDS, Moraes IGD, Westphalen VPD, Menezes R, Carneiro E and Fariniuk LF. Leakage of 4 resin-based root-canal sealers used with a single cone technique. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007; 104:53-7. Nguyen C.A new in vitro method for study of microleakage of dental restorative materials. The University of Adelaide. Australia. Msc thesis. 2008. Nica LM, Didilescu A, Rusu D, Bacila A and Stratul SI. Photomicrographic evaluation of the apical sealing capacity of three types of gutta-percha master cones: an in vitro study. Odontology, May; 1-7: 2011.
O Oddoni PG, Mello I, Coil JM and Antoniazzi JH. Coronal and apical leakage analysis of two different root canal obturation systems. Brazilian Oral Research 2008; 22(3):211-5. Orstavik D. Materials used for root canal obturation: technical, biological and clinical testing. Endodontic Topics 2005; 12: 25–38.
P Peters OA. Current challenges and concepts in the preparation of root canal systems: A review. J Endod 2004; 30(8): 559-567. Pinheiro CR, Guinesi AS, Camargo EJD, Pizzolitto AC and Filho IB. Bacterial leakage evaluation of root canals filled with different endodontic sealers. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: 56-60.
106
References
Pommel L, Jacquot B and Camps J. Lack of correlation among three methods for evaluation of apical leakage. J Endod 2001; 27(5): 347-350.
R Rahimi S, Oskoee SS, Shahi S, Maljaei E, Abdolrahimi M, Mokhtari H and Kazemi A.In vitro comparison of apical microleakage following canal obturation with lateral and thermoplasticized gutta-percha
compaction
techniques. African J Biotech 2010; 9(48): 8235-40. Rajeswari P, Gopikrishna V, Parameswaran A, Gupta T and Kandaswamy D. In vitro evaluation of apical microleakage of Thermafill and Obtura II heated guttapercha in comparison with cold lateral condensation using fluid filtration system. Endodontology 2005; 17(2): 24-31. Rechenberg DK, De Deus G and Zehnder M. Potential systematic error in laboratory experiments on microbial leakage through filled root canals. Int Endod J 2011; 44: 183-194. Romania C, Beltes P, Boutsioukis C and Dandakis C.Ex-vivo area-metric analysis of root canal obturation using gutta-percha cones of different taper. Int Endod J 2009; 42: 491-498. Ruddle CJ. The ProTaper technique.Endodontic Topics 2005; 10: 187–190. Ruddle CJ. Shaping for success-everything old is new again. Int Dent 2007; 11(2): 6-15.
S Saleh AM, Hammad M, Silikas N, Qualtrough A and Watts DC. A laboratory evaluation of the physical and mechanical properties of selected root canal sealers. Int Endod J 2010; 43: 882-8. 107
References
Salz U, Poppe D, Sbicego S and Roulet JF. Sealing properties of a new root canal sealer. Int Endod J; 2009; 42: 1084-9. Santos MC, Vitor C, Cristina S and Tadeu W. Removal of intra canal smear layer by doxycycline: SEM analysis. Aust Endod J 2010; 36: 64–9. Shemesh H, Bos MVD, Wu MK and Wesselink PR. Glucose penetration and fluid transport through coronal root structure and filled root canals. Int Endod J 2007; 40: 866-72. Singla M, Aggarwal V, Logani A and Shah N. Comparative evaluation of rotary ProTaper, Profile, and conventional step-back technique on reduction in Enterococcus faecalis colony-forming units and vertical root fracture resistance of root canals. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 109: 105-10. Souza EM, Wu MK, Shemesh H, Filho IB and Wesselink PR. Comparability of results from two leakage models. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008; 106:309-13. Souza EM, Pappen FG, Shemesh H, Estrela CB and Filho IB. Reliability of assessing dye penetration along root canal fillings using methylene blue. Aust Endod J 2009; 35: 1-6. Souza EM, Wu MK, Sluis LWVD, Leonardo RT,Filho IB and Wesselink PR. Effect of filling technique and root canal area on the percentage of gutta-percha in laterally compacted root fillings. Int Endod J 2009; 42: 1-8. Spencer HR, Ike V and Brennan PA. Review: the use of sodium hypochlorite in endodontics -potential complications and their management. Br Dent J; 202(9): 555-9. Stratul SI, Didilescu A, Grigorie M, Ianes E, Rusu D and Nica L. How accurate replicates the Thermafil System the morphology of the apical endodontic space? An in vitro study. Rom J Morphol Embryol 2011, 52(1):145–151. 108
References
T Taneja S, Chadha R, Dixit S and Nayar R. An in vitro comparison of quantitive dissolution of human pulp in different irrigating solution. J Oral Health Comm Dent 2010; 4(2):28-33. Tasdemir T, Er K, Yildirim T, Burnk K, Celik D, Cora S, Tahan E, Tuncel B and Serper A. Comparison of the sealing ability of three filling techniques in canals shaped with two different rotary systems: A bacterial leakage study. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: 129-34. Tasdemir T, Yesilyurt C, Ceyhanli KT, Celik D and Er K. Evaluation of apical filling after root canal filling by 2 different techniques. J Canad Dent Assoc; 75(3): 201-5.
V Vaudt J, Bitter K and Kielbassa AM. Evaluation of rotary root canal instruments in vitro: a review. Endo 2007; 1(13): 189-203. Violich DR and Chandler NP. The smear layer in endodontics- a review. Int Endod J 2010; 43: 2-15.
Von Fraunhofer JA, Fagundes DK, McDonald NJ and Dumsha TC. The effect of root canal preparation on microleakage within endodontically treated teeth: an in vitro study. Int Endod J 2000; 33: 355-60. Von Fraunhofer JA, Koltz DA and Jones OJ.Microleakage within endodontically treated teeth using a simplified root canal preparation technique: An in vitro study. Gen Dent 2005; November-December: 439-44.
109
References
Von Fraunhofer JA and Kurtzman GM. Resin-based sealing of root canals in endodontic therapy. International magazine of endodontic 2008; 3: 44-8.
W Whitworth J. Methods of filling of root canals: principle and practice. Endodontic Topics 2005; 12: 2–24. Williamson AE, Marker KL, Drake DR, Dawson DV and Walton RE. Resinbased versus gutta-percha-based root canal obturation: influence on bacterial leakage in an in vitro model system. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: 292-6.
X Xu Q, Fan MW, Fan B, Cheung GSP and Hu HI. A new quantitative method using glucose for analysis of endodontic leakage.Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005; 99:107-11. Xu Q, Ling J, Cheung GSP and Hu Y. A quantitative evaluation of sealing ability of 4 obturation techniques by using a glucose leakage test. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007; 104:109-13.
Y Yang GB, Zhou XD, Zheng YL, Zheng H, Shu Y and Wu HK. Shaping ability of progressive versus constant taper instruments in curved root canals of extracted teeth. Int Endod J 2007; 40: 707-14.
110
References
Yeng T, Messer HH and Parashos P. Treatment planning the endodontic case. Aust Dent J (Suppl.) 2007; 52: 32-7. Yilmaz Z, Tuncel B, Ozdemir HO and Serper A. Microleakage evaluation of roots filled with different obturation techniques and sealers. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: 124-8. Yin Ng RP. Sterilization in root canal treatment: current advances. Hong Kong Dent J 2004; 1: 52-7. Young GR, Parashos P and Messer HH. The principle of techniques for cleaning root canals. Aust Dent J (Suppl.) 2007; 52: 52-63. Yucel AC and Ciftci A. Effects of different root canal obturation techniques on bacterial penetration. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2006; 102:88-92.
Z Zebnder M. Root canal irrigants. J Endod 2006; 32: 389-98. Zhang W, Li Z and Peng B. Assessment of a new root canal sealer‟s apical sealing ability. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 107: 79-82. Zhang W, Suguro H, Kobayashi Y, Tsurumachi T and Ogiso B.Effect of canal taper and plugger size on warm gutta-percha obturation of lateral depressions. J Oral Sc 2011; 53(2): 219-24.
111
Appendices
Appendix I: Leakage current immediately (at 0 days) in µA Groups A1
A2
B1
B2
C
Positive Group
Negative Group
Tooth No. 1
1.77
1.21
3.01
3.13
0.71
6.02
0.00
Tooth No. 2
2.1
1.36
3.43
3.74
1.4
6.13
0.00
Tooth No. 3
1.98
1.19
3.25
3.91
0.70
6.21
0.00
Tooth No. 4
2.21
1.41
3.72
3.73
0.73
5.98
0.00
Tooth No. 5
2.06
1.54
3.9
3.89
0.4
6.23
0.00
Tooth No. 6
1.74
1.32
3.87
4.2
1.2
-
-
Tooth No. 7
1.89
1.44
3.23
4.02
1.1
-
-
Tooth No. 8
1.95
1.63
3.24
4.59
1.3
-
-
Tooth No. 9
1.93
1.82
3.34
4.73
1.4
-
-
Tooth No. 10
2.3
1.9
4.21
4.74
0.3
-
-
Teeth No.
112
Appendix II: Leakage current (at 5 days) in µA Groups A1
A2
B1
B2
C
Positive Group
Negative Group
Tooth No. 1
2.87
2.31
4.45
4.63
2.13
9.93
0.00
Tooth No. 2
3.05
2.56
4.84
4.84
2.17
10.15
0.00
Tooth No. 3
2.79
2.29
4.67
5.66
1.93
10.35
0.00
Tooth No. 4
3.31
2.51
4.57
4.14
1.73
10.56
0.00
Tooth No. 5
3.16
2.66
5.08
5.04
1.64
10.59
0.00
Tooth No. 6
2.84
2.33
5.05
5.97
1.67
-
-
Tooth No. 7
2.98
2.38
4.65
5.12
1.63
-
-
Tooth No. 8
3.05
2.55
4.34
5.69
2.54
-
-
Tooth No. 9
3.03
2.53
4.44
5.83
2.72
-
-
Tooth No. 10
2.85
2.45
5.73
5.89
1.54
-
-
Teeth No.
113
Appendix III: Leakage current (at 10 days) in µA Groups A1
A2
B1
B2
C
Positive Group
Negative Group
Tooth No. 1
6.87
5.65
6.95
7.29
4.63
13.94
0.00
Tooth No. 2
6.95
5.76
6.93
7.49
4.65
15.75
0.00
Tooth No. 3
6.77
5.56
6.99
8.34
4.02
15.73
0.00
Tooth No. 4
7.3
6.14
6.95
6.79
3.87
15.78
0.00
Tooth No. 5
7.17
5.93
7.53
5.01
3.99
15.81
0.00
Tooth No. 6
6.79
5.57
7.95
8.49
4.03
-
-
Tooth No. 7
6.92
5.71
7.64
7.78
3.99
-
-
Tooth No. 8
6.94
5.64
6.66
8.35
5.04
-
-
Tooth No. 9
7.04
5.88
6.75
8.49
5.21
-
-
Tooth No. 10
6.84
5.53
8.81
8.55
4.01
-
-
Teeth No.
114
Appendix IV: Leakage current (at 15 days) in µA Groups A1
A2
B1
B2
C
Positive Group
Negative Group
Tooth No. 1
9.06
8.45
8.82
8.99
7.54
17.95
0.00
Tooth No. 2
9.15
8.53
8.87
9.19
7.55
18.71
0.00
Tooth No. 3
8.94
8.34
8.79
10.13
6.93
18.31
0.00
Tooth No. 4
9.49
8.9
8.92
8.58
6.79
18.53
0.00
Tooth No. 5
9.36
8.73
9.53
9.4
6.93
18.73
0.00
Tooth No. 6
8.96
8.36
9.93
10.19
6.94
-
-
Tooth No. 7
9.11
8.5
9.6
9.56
6.9
-
-
Tooth No. 8
9.13
8.44
8.76
10.12
7.95
-
-
Tooth No. 9
9.23
8.67
8.86
10.22
8.15
-
-
Tooth No. 10
8.97
8.33
10.83
10.31
6.91
-
-
Teeth No.
115
Appendix V: Leakage current (at 20 days) in µA Groups A1
A2
B1
B2
C
Positive Group
Negative Group
Tooth No. 1
9.34
9.08
10.02
10.52
8.53
17.97
0.00
Tooth No. 2
9.4
9.06
10.17
10.69
8.42
18.26
0.00
Tooth No. 3
9.2
8.86
9.89
11.69
7.92
18.31
0.00
Tooth No. 4
9.71
9.4
10.12
10.09
7.78
18.53
0.00
Tooth No. 5
9.62
9.27
10.83
10.91
7.83
18.5
0.00
Tooth No. 6
9.22
8.9
11.13
11.71
7.93
-
-
Tooth No. 7
9.36
9.04
10.9
11.01
7.88
-
-
Tooth No. 8
9.32
8.97
9.96
11.59
8.97
-
-
Tooth No. 9
9.52
9.18
10.06
11.72
9.06
-
-
Tooth No. 10
9.21
9.18
12.04
11.9
7.9
-
-
Teeth No.
116
Appendix VI: Leakage current (at 25 days) in µA Groups A1
A2
B1
B2
C
Positive Group
Negative Group
Tooth No. 1
10.26
9.92
11.22
12.02
9.11
18.5
0.00
Tooth No. 2
10.28
9.63
11.27
11.79
8.95
18.8
0.00
Tooth No. 3
10.15
9.73
11.19
13.09
8.43
18.8
0.00
Tooth No. 4
10.6
10.12
11.52
11.19
8.26
19.01
0.00
Tooth No. 5
10.54
9.53
11.93
12.01
8.37
19.02
0.00
Tooth No. 6
10.15
9.29
12.22
12.85
8.46
-
-
Tooth No. 7
10.23
9.27
12.3
12.41
8.45
-
-
Tooth No. 8
10.26
9.07
11.16
12.85
9.48
-
-
Tooth No. 9
10.42
9.66
11.25
12.92
9.56
-
-
Tooth No. 10
10.1
10.31
13.15
12.08
8.38
-
-
Teeth No.
117
Appendix VII: Leakage current (at 30 days) in µA Groups A1
A2
B1
B2
C
Positive Group
Negative Group
Tooth No. 1
10.56
10.1
11.62
12.51
9.3
18.6
-
Tooth No. 2
10.59
9.98
11.69
12.49
9.1
18.9
-
Tooth No. 3
10.48
10.03
11.58
13.5
8.55
18.8
-
Tooth No. 4
10.9
10.4
11.9
11.64
8.4
19.01
-
Tooth No. 5
10.83
9.9
12.3
12.57
8.53
19.2
-
Tooth No. 6
10.5
9.6
12.54
13.25
8.6
-
-
Tooth No. 7
10.51
9.58
12.7
12.8
8.62
-
-
Tooth No. 8
10.6
9.08
11.55
13.39
9.6
-
-
Tooth No. 9
10.71
9.91
11.6
13.4
9.7
-
-
Tooth No. 10
10.3
10.6
13.45
13.18
8.5
-
-
Teeth No.
118
تقييى يقاويح انتسشب نقُىاخ انجزوسانًحشىج تُىعيٍ يٍ انخىاتى و ثال ثح أَىاع يٍ تقُياخ انغهق تا نطشيقح انكهشتائيح انكيًياويح (دساسح يختثشيح يقاسَح ) سسانح يقذيح نًجهس سكىل طة األسُاٌ,يجًىعح انعهىو انطثيح,في جايعح انسهيًاَيح كجزء يٍ يتطهثاخ يُح دسجح انًاجستيش في يعانجح األسُاٌ
يٍ قثم سَجذس يحًىد عثًاٌ تكانىسيس في طة و جشاحح انفى األسُاٌ
تأششاف األستار انذكتىس سالو داود انقيسي تكانىسيس في طة و جشاحح انفى األسُاٌ ياجستيش في يعانجح األسُاٌ
٢٠١١و
٢٧١١ك
١٤٣٢ھ
