Nabeel Alsabeeha Alan G. T. Payne Rohana K. De Silva Michael V. Swain

Authors’ affiliations: Nabeel Alsabeeha, Alan G. T. Payne, Rohana K. De Silva, Michael V. Swain, Oral Implantology Research Group, Sir John Walsh Research Institute, School of Dentistry, Dunedin, New Zealand Correspondence to: Alan G. T. Payne Oral Implantology Research Group Sir John Walsh Research Institute School of Dentistry 280 Great King Street, PO Box 647 Dunedin, New Zealand Tel.: þ 64 3 479 7119 Fax: þ 64 3 479 5079 e-mail: [email protected]

Mandibular single-implant overdentures: a review with surgical and prosthodontic perspectives of a novel approach

Key words: attachment system, early loading, mandibular, novel design, overdenture, platform switch, single implant, wide diameter Abstract Objectives: To review the literature on mandibular single-implant overdentures (opposing complete maxillary dentures), and present surgical and prosthodontic perspectives of a novel approach for this treatment option. Material and methods: An electronic search through the databases of Pubmed, Embase and Medline using the linked key words ‘mandibular single implant overdentures’ was performed. The search was limited to English language articles published up to August 2008. Hand searches through articles retrieved from the electronic search, peer-reviewed journals and recent conference proceedings were also conducted. Results: A limited number of reports were identified on mandibular single-implant overdentures (opposing maxillary complete dentures). They comprised of case-series reports, short-term prospective trials and current randomized-controlled clinical trials. Different loading protocols with different implant systems have been used, but always with regular diameter implants. Specific anatomical and vascular dangers of the mandibular midline symphysis are identified including a novel surgical approach using a currently available short, wide diameter tapered implant. In addition, the prosthodontic rationale for using a larger attachment system (incorporating a platform switch) for mandibular single-implant overdentures is described. Conclusion: The review reveals that there is a lack of published randomized clinical trials using mandibular single-implant overdentures, opposing maxillary complete dentures. Without the evidence from randomized clinical trials, routine use of this novel approach cannot be recommended, compared with using regular diameter implants and matching attachment systems.

Date: Accepted 7 October 2008 To cite this article: Alsabeeha N, Payne AGT, De Silva RK, Swain MV. Mandibular single-implant overdentures: a review with surgical and prosthodontic perspectives of a novel approach. Clin. Oral Impl. Res. 20, 2009; 356–365. doi: 10.1111/j.1600-0501.2008.01666.x

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For edentulous patients, adequate retention and stability of their complete maxillary and mandibular dentures are fundamental determinants for a successful treatment outcome. Historically, efforts have been made by the profession to enhance the retention and stability of complete dentures by understanding their physical, biological and mechanical determinants (Jacobson & Krol 1983a, 1983b, 1983c). Higher degrees of prostho-

dontic success can be achieved with complete maxillary dentures (Zarb & Bolender 2004). Similar successful outcomes for opposing complete mandibular dentures are influenced by relentless residual ridge resorption (Tallgren 1972; Enlow 1976). From the mid 1980s, concepts for mandibular implant overdentures using Straumann or Branemark implants appeared in the evidence-based literature (Ledermann

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1983; Stalblad et al. 1985; Zarb et al. 1985). Long-term studies on mandibular overdentures with two to four splinted or unsplinted implants using different systems have confirmed successful and predictable outcomes (Spiekermann et al. 1995; Jemt et al. 1996; Mericske-Stern 1996; Davis & Packer 1999; Meijer et al. 2003; Attard & Zarb 2004; Naert et al. 2004; Visser et al. 2006). Current consensus is that reducing the numbers of implants from four to two does not affect the implant or the prosthodontic success rates (Klemetti 2008). Over the past 5 years, a proposed ‘first-choice’ standard of care for edentulous patients using mandibular two-implant overdentures (opposing complete maxillary dentures) has enjoyed acceptance worldwide using different implant systems and loading protocols (Feine et al. 2002; Payne et al. 2003a; Attard & Zarb 2004; Carlsson et al. 2004; Naert et al. 2004; Marzola et al. 2007). This is despite certain concerns and reservations related to determining a standard of care for the edentulous mandible (Zarb 2005; Fitzpatrick 2006). With the growth in the ageing population worldwide, it is inevitable that more elderly edentulous patients will utilize prosthodontic services offering mandibular two-implant overdentures. Authors have anticipated a future shift in this treatment paradigm towards complete maxillary dentures being opposed by mandibular singleimplant overdentures (Carlsson 2003). This would be another treatment option to resolve the edentulous predicament, for some patients, depending on the selection criteria used (Zarb 2004). In developed countries, patients’ preferences for a particular mandibular overdenture treatment will be influenced by the number of implants used, the respective attachment system recommended and the cost, which could still be a prohibitive factor for some elderly edentulous patients (Carlsson et al. 2004; Takanashi et al. 2004). In developing countries, financial constraints of socioeconomic groups could also make the provision of a proposed minimum standard of care (with mandibular two-implant overdentures) or other treatment options (with fixed implant bridges) questionable. Furthermore, an ‘appropriatech’ philosophy challenges clinicians and researchers worldwide to develop an appropriate prosthodontic treat-

ment option for edentulism that adheres to basic principles with less reliance on highly demanding technicalities (Owen 2004). This option is proposed to be amenable on a global scale for a wider range of edentulous populations in different socioeconomic groups (Owen 2004). The ultimate goal would be the smallest intervention that offers a satisfactory improvement in the support, retention and stability of complete dentures. Hence, with the option of less invasive implant surgery in the anterior mandible, with reduced implant components and prosthodontic costs, the concept of the mandibular single-implant overdentures (to oppose the successful conventional complete maxillary dentures) is a reality for elderly edentulous populations. Traditionally, the anterior mandible has been considered a rather safe, preferred site for implant placement for overdentures (Engquist et al. 1988; Jemt et al. 1996; Bergendal & Engquist 1998; Mraiwa et al. 2003), even with severe residual ridge resorption and the anticipation of a relatively less challenging surgical procedure (Geertman et al. 1996). The objectives of this review were to review the literature on mandibular single-implant overdentures (opposing complete maxillary dentures), and to present surgical and prosthodontic perspectives of a novel approach for this treatment option.

Materials and methods The search strategy involved an electronic search through the databases of PubMed, Embase and Medline using the linked key words ‘mandibular single implant overdentures’. The aim was to identify all publications reporting on mandibular singleimplant overdentures up to and including August 2008. The search was limited to English language articles that contained all or part of the key words in their headings. The electronic search was further augmented by a hand search through the following journals: Clinical Implant Dentistry and Related Research, Clinical Oral Implants Research, Implant Dentistry, International Journal of Oral and Maxillo-facial Implants, International Journal of Oral and Maxillo-facial Surgery, International Journal of Periodontics and Restorative Dentistry, International Journal of

 c 2009 The Authors. Journal compilation  c 2009 John Wiley & Sons A/S

Prosthodontics, Journal of Clinical Periodontology, Journal of Dental Research, Journal of Oral Implantology, Journal of Oral and Maxillo-facial Surgery, Journal of Periodontology, Journal of Prosthodontics, and the Journal of Prosthetic Dentistry. The titles and the abstracts of all the reports identified through the electronic searches were scanned independently by the first two authors (N.A., A.G.T.P.). In addition, for recent reports on mandibular single-implant overdentures, recent conference proceedings across the period 2006–2007 were also searched. Follow-up personal communications were then conducted to clarify any forthcoming manuscripts in press or unpublished research work on mandibular single-implant overdentures with relevant abstracts.

Results Only seven eligible reports on mandibular single implant overdentures were found (Table 1). These specifically comprised of two prospective clinical studies (Cordioli et al. 1997; Liddelow & Henry 2007), two case series (Krennmair & Ulm 2001; Wolfart et al. 2008) and three relevant abstracts from the conference proceedings on early findings from current clinical trials (Kronstrom et al. 2007; MacEntee & Walton 2007; Walton & MacEntee 2008). One research centre had two abstracts from the conference proceedings from the same randomized-controlled clinical trial; hence, our findings were actually related to six reports only (MacEntee & Walton 2007; Walton & MacEntee 2008). The earliest evidence was from a prospective longitudinal study that demonstrated the successful outcome of mandibular overdentures retained by single implants in the mandibular symphysis (Cordioli et al. 1997). A total of 21 edentulous participants (mean age 74.2 years) were followed for 5 years. A standard two-stage surgical approach and a conventional loading protocol were used. A regular 3.75-mm-diameter turned machined surface, as well as hydroxyapatite-coated implants of one system (3i, Implant Innovations Inc., Palm Beach, FL, USA) and different attachments (Implant Innovations Inc., and Nobel Biocare, Goteborg, Sweden) were used. Implant lengths, although stated as always being 47 mm,

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Implant: 100% Prosthesis: 100%

Implant: 100% Prosthesis: 100%

Regular 2.25 mm ball abutment and adjustable gold matrix

Regular 2.25 mm retentive anchors (ball abutments) and gold matrices

Mandibular midline

2 patients/13 mm

No details provided

2

Mandibular midline 43

Conventional

Camlog 3.8 mm

Straumann 4.1 mm Walton& MacEntee (2008)

Wolfart et al. (2008)

Case series with 2-stage o1-year follow-up

Conventional RCT with a 1-year follow-up MacEntee & Walton (2007)

1-stage

Regular 3.5 mm old style Implant: 89% large ball abutments and Prosthesis: 89% rubber black O-ring matrices patients/18 mm patients/15 mm patients/13 mm patients/11.5 mm patient/10 mm 3 4 8 9 1 Mandibular midline 25 Branemark 4 mm Immediate and early Prospective study with a 1-year follow-up Liddelow & Henry (2007)

1-stage

Implant: 82% Prosthesis: 82% Regular 2.25 mm ball abutments and gold matrices RCT with a 1-year follow-up Kronstrom et al. (2007)

1-stage

Immediate

Branemark 3.75 mm

17

Mandibular midline

Majority of patients had implants of 15 mm length

Implant: 100% Prosthesis: 100% Regular 2.25 mm ball abutments and Dalla Bona type matrices 8 patients/13 mm 1 patient/15 mm Mandibular midline 9 Conventional Case series with 18-month follow-up Krennmair & Ulm (2001)

2-stage

IMZ and Frialit-2 3.75 mm

Implant: 100% Prosthesis: 100% Regular 2.25 mm Branemark ball abutments and small white rubber O-ring matrices (3i) 9 patients/10 mm 11 patients/13 mm 1 patient/15 mm Mandibular midline 21 3i 3.75 and 4 mm Conventional Prospective study with 5-year follow-up Cordioli et al. (1997)

2-stage

No. of implants used Implant system and diameter Loading protocol Surgical approach Study type Author

Table 1. Summary of currently available reports on mandibular single-implant overdentures

Implant site

No. of patients/ implant length

Attachment system

Implant/ prosthesis success/survival rate

Alsabeeha et al . Mandibular single implant overdentures

were actually all in the 10–15 mm range. No implant failures were reported and prosthodontic maintenance events were only related to wear of the rubber O-ring matrices of the attachment systems. It was identified that the matrices needed to be replaced twice yearly to maintain adequate retention for the overdentures. A subsequent case series reported on another nine edentulous patients (mean age 82.2 years) who were followed for 18 months also using a conventional loading protocol (Krennmair & Ulm 2001). Regular 3.75-mm-diameter turned machined surface implants (IMZ, Interpore International, Irvine, CA, USA) and roughened surface implants were used (Frialit-2, Friatec, Mannheim, Germany). Implant lengths were again 13–15 mm. Again, a 100% implant success rate was achieved. All authors reported that patient satisfaction with mandibular single-implant overdentures was significantly improved compared with conventional mandibular dentures. From these two initial reports, this treatment was proposed as an approach for older adults with severe residual ridge resorption and a medium-term treatment service for an ageing population who could be octogenarians (Cordioli et al. 1997; Krennmair & Ulm 2001). A recently published case-series report from an ongoing clinical study (Wolfart et al. 2008) used single roughened-surface 3.8-mm-diameter and 13-mm-long implants (Camlog, Wimshiem, Germany) in the midline symphysis of the mandible of two patients (aged 48 and 61 years) to support their overdentures. After a conventional healing period of 3 months, small ball abutments 2.25 mm in diameter with corresponding gold matrices (Cendres and Metaux, Bienne, Switzerland) were used as attachment systems. The follow-up time for the two patients was o1 year. Outcome measures using a modified version of the Oral Health Impact Profile revealed an improvement in the quality of life of the two patients compared with the situation before the interventions. In addition, an improvement in masticatory function using objective measures was also reported by the authors. Two prospective trials and one randomized-controlled clinical trial using both conventional and immediate loading protocols were also found using roughened surface implants (Kronstrom et al. 2007;

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Liddelow & Henry 2007; MacEntee & Walton 2007; Walton & MacEntee 2008). The prospective trials were reported up to 1 year and used an immediate loading protocol (Kronstrom et al. 2007; Liddelow & Henry 2007). The actual implant success rates were not reported in either of these preliminary reports. The findings were, however, contradictory. In one study, a cohort of 36 participants was treated with one- or two-implant mandibular overdentures (Kronstrom et al. 2007). Regular 3.75-mm-diameter implants (TiUnite, Nobel Biocare) were again placed in the midline symphysis of the mandible of 17 participants (mean age 67 years) of the mandibular single-implant overdenture group. The implants were 10–15 mm long, the majority being 15 mm long, with implants shorter than 10 mm not being used. These implants were immediately loaded with overdentures on the same day of the surgery. Three implants out of 17 failed and survival rates were reported at 82%. On the other hand, another report (Liddelow & Henry 2007) using 28 implants in 28 participants (mean 69.8 years) of regular 4 mm diameter of the same system reported a survival rate of 100%. Prosthodontic components were large 3.5 mm ball abutments with black rubber rings as matrices in grey plastic housings. On critical review, it was noted that out of the 28 single implants placed for planned immediate loading, three had to be transferred to a conventional loading approach as they did not meet the required primary stability necessary. Had these three implants been included in the data analyses, the survival rate would actually have been 89%. Furthermore, 10 out of the 25 participants were actually assigned to a 6-week early loading protocol, to allow optimum peri-implant tissue healing beneath the overdentures before loading. We deduce that although there was a lack of standardization of the loading protocols for the original 28 participants, there was still an indication that a 6-week early loading protocol was preferred to an immediate loading one for this treatment. The randomized clinical trial compared mandibular overdentures retained by either one or two implants in 86 participants (mean age 67 years) and primarily evaluated patient outcomes (MacEntee & Walton 2007; Walton & MacEntee 2008).

Both groups were equally satisfied with the treatments provided. A one-stage surgical approach with a conventional loading of regular 4.1-mm-diameter implants (Straumann, Waldenburg, Switzerland) at 8 weeks was adopted for the 44 participants with mandibular single-implant overdentures. Prosthodontic components were small 2.25 mm ball abutments (retentive anchors) and gold matrices. Success rates of 100% were reported for 34 participants of the mandibular single-implant overdenture treatment group followed for 1 year. Time for prosthodontic maintenance was also similar for both groups (P40.1). On the other hand, the single-implant group had lower component costs, and lower mean and median times for surgery, postsurgical denture maintenance and denture reline for implants; these differences were statistically significant (each Po0.02) and clinically important (post-surgical maintenance time averaged 186 vs. 268 min). Overall, within the literature already published with full-length articles, a total of 57 implants placed in the midline symphysis were used to retain 57 mandibular singleimplant overdentures (Cordioli et al. 1997; Krennmair & Ulm 2001; Liddelow & Henry 2007; Wolfart et al. 2008). In this, 50.8% of the regular diameter implants were 13 mm in length, with only 17.5% being 10 mm. The use of implants shorter than 10 mm was not reported by any of the authors.

Discussion As a result of this review, we have identified that there are only a small number of reports currently available on the use of mandibular single-implant overdentures when opposing maxillary complete dentures. They comprise a mixture of case-series reports, short-term prospective trials and a current randomized-controlled clinical trial (Cordioli et al. 1997; Krennmair & Ulm 2001; Kronstrom et al. 2007; Liddelow & Henry 2007; MacEntee & Walton 2007; Walton & MacEntee 2008; Wolfart et al. 2008). Different loading protocols with different implant systems have been used. Regular diameter implants (3.75, 3.8, 4 or 4.1 mm) and their matching attachment systems have been used as an extrapolation of the implant components used for mandibular two-implant overdentures. This review has

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therefore identified a need for more randomized clinical trials with this treatment. Experienced operators are aware of several dangers related to surgical placement of single implants in the mandibular midline, namely implant placement in the hard bone of the mandibular symphysis, anatomical aspects of residual ridge resorption and the presence of certain blood vessels in the area. Traditionally, implant placement in the mandibular symphysis is avoided, perhaps as an over-precaution due to the anatomical aspects of the symphysis area resulting in Lekholm & Zarb Type 1 bone (Lekholm & Zarb 1985; Worthington 1992; Buser & Maeglin 1996). The rationale appears to be related to fear of thermal damage following site preparation in the dense bone frequently encountered in the symphysis area (Eriksson & Adell 1986; Worthington 1992; Buser & Maeglin 1996; Quirynen & Lekholm 2008). Severe residual ridge resorption of the anterior mandible frequently results in prominent genial tubercles, the attachment sites for the genioglossus and geniohyoid muscles (van den Bergh et al. 1998). After residual ridge resorption, the genial tubercles become even more exaggerated. Preparation with ridge re-contouring for proper placement of an implant would preferably have to be carried out anterior to this structure. Inadvertent severance of the genioglossus muscle attachment at this site could result in tongue retrusion and subsequent airway obstruction (van den Bergh et al. 1998). The genial tubercles and their muscle attachments limit the resorptive process lingually, leaving the anterior mandible lingually inclined (Enlow 1976). A lingual undercut area is formed by the exaggerated anterior location of the genial tubercles anteriorly (labially) and the sublingual fossa laterally (lingually) (Quirynen & Lekholm 2008). The lingual foramen is situated in the midline, at the level of or superior to the mental tubercles in 85–99% of the mandibles (McDonnell et al. 1994; Mraiwa et al. 2003). This is well identified in radiographic textbooks (Mansong-Hing 1990). The content of the foramen has been debated between vascular, nerve tissue content or neurovascular content (Mraiwa et al. 2003). There are also vital blood vessels within the floor of the mouth and bony foramina in the mid-symphyseal region (McDonnell et al. 1994; Hofschneider et al. 1999;

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Tepper et al. 2001). The sublingual artery with a mean diameter of approximately 2 mm supplies numerous anatomical structures, including the sublingual gland, the mylohyoid, geniohyoid and genioglossus muscles, mucous membranes of the floor of the mouth and the lingual gingiva (Bavitz et al. 1994; Hofschneider et al. 1999; Quirynen & Lekholm 2008). One of its branches pierces mylohyoid and anastomoses with branches from the submental artery. Another branch courses anteriorly through the mandibular gingivae to anastomose with its contralateral counterpart. A single artery arises from this anastomosis to enter the lingual foramen of the mandible typically on the posterior aspect of the symphysis, immediately above the genial tubercles (Standring 2005). The submental artery, a branch of the facial artery, runs along the inferior surface of the mylohyoid muscle lateral to the anterior belly of the digastric muscle and hence also runs adjacent to the lower lingual border of the mandible (Quirynen & Lekholm 2008). As a result, there have been several case reports of severe haemorrhage in the floor of the mouth, with life-threatening complications following implant placement in the anterior mandible (Kalpidis & Setayesh 2004; Woo et al. 2006; Quirynen & Lekholm 2008). When examining the actual sites of implant placement in these reports, it is found that most of them relate to multiple implant placements in the anterior mandible; however, many sites associated with this problem are in the midline region (tooth sites 31, 41) (Laboda 1990; Mason et al. 1990; ten Bruggenkate et al. 1993; Niamtu 2001; Boyes-Varley & Lownie 2002). In resorbed mandibles, the median lingual foramen, together with accessory lingual foramina, can be found in the midline below the genial tubercles (Kalpidis & Setayesh 2004). Lingual perforation results in a massive haematoma, which, enclosed within the cervical fascia, can displace the tongue and the floor of the mouth posterosuperiorly, causing upper airway obstruction (Kalpidis & Setayesh 2004). This review has also identified that implants shorter than 10 mm were not used frequently for the single implants placed in the mandibular symphyses. However, it would be logical to expect that for elderly patients like octogenarians, after decades of

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edentulism, there may a higher probability of 10 mm or less of residual mandibular bone in the midline. Short implants have often been used surgically to accommodate mandibular residual ridge resorption (Worthington 1992; ten Bruggenkate et al. 1998; Romeo et al. 2006). Consensus among researchers as to what constitutes a short implant is lacking with a range of 4–10 mm (Bass & Triplett 1991; Keller 1995; ten Bruggenkate et al. 1998; Friberg et al. 2000; Stellingsma et al. 2000; Renouard & Nisand 2006). High success and survival rates with both fixed implant bridges and removable overdentures using short implants from different systems are known (Bass & Triplett 1991; Friberg et al. 1991; Branemark et al. 1995; ten Bruggenkate et al. 1998; Friberg et al. 2000; Stellingsma et al. 2000). Conversely, failures of short implants compared with their longer counterparts have also been observed (Friberg et al. 1991; ten Bruggenkate et al. 1998). Wide diameter implants (44.5 mm) using different implant systems that are also short in length are also utilized for single and multiple tooth replacement in the molar regions of partially edentulous jaws. High success and survival rates of more than 90% have been reported in some studies (Bahat & Handelsman 1996; Khayat et al. 2001; Krennmair & Waldenberger 2004; Anner et al. 2005). Less favourable results are reported in others (Ivanoff et al. 1999; Shin et al. 2004), which have been attributed to surgical learning curves for operators placing wide diameter implants (Ivanoff et al. 1999; Shin et al. 2004), implant design (Ivanoff et al. 1999; Khayat et al. 2001) and the surgical technique used (Ivanoff et al. 1999). Surgical techniques often require modification due to anatomical constraints. We argue that the actual rationale of a surgical prescription of a regular diameter (3.75–4.1 mm) implant in resorbed anterior mandibles of elderly patients for mandibular single implant overdentures should be questioned. This applies especially to mandibular residual ridge resorption bone quantity categories D or E (Lekholm & Zarb 1985); orders V or VI (Atwood 1963); and prosthodontic diagnostic indices of class III or IV (McGarry et al. 1999). The alternative use of wide diameter implants

would be logical, especially with advanced mandibular residual ridge resorption creating a flat, but broad ridge in the midline of the mandible (Atwood & Coy 1971; Cawood & Howell 1988). Equally so, the rationale for a prosthodontic prescription of regular-sized attachment systems that have been used for mandibular two-implant overdentures can also be questioned. If the mandibular single-implant overdenture option is chosen, then it is imperative to minimize rotational movements by using larger prosthodontic attachment systems that would be able to maximize support, retention and stability rather than just using those similar to mandibular twoimplant overdentures (Jacobson & Krol 1983a, 1983b, 1983c). Therefore, surgical perspectives of a novel approach using a wide diameter implant with larger prosthodontic components for mandibular single-implant overdentures (opposing complete maxillary dentures) are described. The novel design

A commercially available short, wide diameter, roughened surface-tapered implant (Max-8; Southern Implants (Pty) Ltd, Irvine, CA, USA), originally designed for immediate placement in molar extraction sites, is used. It is a self-tapping implant 8 mm in diameter, with a prosthodontic platform of 6.5 mm in diameter and a standard external hexagon 2.7 mm in size. The 3 mm coronal section of the implant body is parallel sided and constitutes the area of greatest dimension with the body tapering apically. The implant is available in lengths of 7, 9 and 11 mm. Previous randomized-controlled clinical trials (albeit for regular diameter implants) have already validated successful shortterm outcomes of this particular roughened surface topography in the anterior mandible using different loading protocols (Tawse-Smith et al. 2001, 2002; Payne et al. 2003a, 2003b). The geometry and surface topography of this particular implant were favourable for its novel application in the midline of the mandible. The attachment system comprises a custom-designed large ball abutment (patrix) and a corresponding large plastic matrix. The ball abutment (patrix) is 5.9 mm in diameter with a platform 5 mm in diameter and made up of unalloyed titanium with a

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titanium nitride coating. Hence, a platform switch has been incorporated with the design features of the ball abutment (Lazzara & Porter 2006). The plastic matrix is 7 mm in diameter and 5 mm in height. Evidence for the short-term successful application of this attachment system (albeit with regular diameter ball abutments) has also been reported in terms of minimal prosthodontic maintenance requirements (Watson et al. 2002; Payne et al. 2003a).

Rationale for the novel design Selection of width and taper

To consider using an 8-mm-diameter implant, previous anatomical studies have described the morphological changes affecting the height and width of the edentulous mandible following total tooth loss (Atwood 1963; Atwood & Coy 1971; Denissen et al. 1984; Cawood & Howell 1988; Blahout et al. 2007). The width of basal bone-resorbed edentulous mandibles in the midline showed no significant difference across the different orders of the classification shown by Atwood (1963). The average maximum widths were  12 mm in order II (post-extraction residual ridges);  12.1 mm in order III (high, well-rounded ridges);  11.7 mm in order IV (knife-edge residual ridges); and  11.9 mm in order V (low well-formed residual ridges). No values were given for order VI (depressed or gutter residual ridge) but it is presumed to be similar to order V. Cawood & Howell (1988), on the other hand, in their randomized cross-sectional study of 300 skulls in the Greig Collection at the Royal College of Surgeons of Edinburgh, Scotland, found minimum values for mandibular residual ridge width in the midline of  7.8 ( 1.33) mm for moderate edentulous resorption;  6.29 ( 0.87) mm for severe edentulous resorption; and  3.5 ( 1.63) mm for extreme edentulous resorption. However, these measurements were taken at the crest of the alveolar bone and

no measurements were made at the basal bone level. Denissen et al. (1984) also measured the horizontal width in the midline at a point midway between the crest of the ridge and the inferior border of atrophic mandibles in 18 human cadavers with 36 specimens. A range between a low width of 10 mm and a high width of 14 mm was found, although measurements were across the mandible from the mental foramen to the midline. Blahout et al. (2007) performed an anatomic study of 41 left mandibular halves (26 females, 15 males) supplied by the Institute of Anatomy, University of Vienna. The mean age of the specimens was 82.4 years and they were grouped according to the Cawood & Howell classification of residual ridge resorption. The maximum mandibular mid-sagittal widths in the area of the previous central incisors were found to be    

14.3 mm in 10 class III residual ridges (high, well-rounded ridge); 12.5 mm in seven class IV residual ridges (knife-edge ridge); 13.3 mm in five class V residual ridges (low, well-rounded ridge); and 12 mm in 13 class VI residual ridges (depressed ridge).

The maximum width of the anterior region of the mandible was minimally reduced during all remodelling and resorptive processes. Statistical analysis notably showed that there was only a 2 mm difference in width between the anterior region of mildly atrophic mandibles and that of severely atrophic mandibles. This excluded the alveolar ridge, which was subject to the intense remodelling and resorptive processes that eventually result in the complete loss of the alveolar ridge to leave the remaining basal bone. Their anatomical findings indicated that Cawood & Howell (1988) class V residual ridges (low, wellrounded ridge) and class VI residual ridges (depressed ridge) were mostly composed of very strong compact basal bone. With regard to bone quality, they also found a clear predominance of type 2 bone quality (Lekholm & Zarb 1985) as opposed to type 3 bone in all sections. These anatomical findings support the notion that with moderate to severe residual ridge resorption, an adequate width of basal bone still exists at the mandibular

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midline to accommodate wide diameter implants as large as 8 mm in diameter. Edentulous mandibles with bone quantities C, D and E (Lekholm & Zarb 1985) and a minimum width and height of 10 and 7 mm, respectively, at the mandibular symphysis could be indications for the application of this approach. Good bone quality at the mandibular symphysis (types 1 and 2) (Lekholm & Zarb 1985) will be encountered more often than not, as opposed to type 3 bone for patients with severe mandibular residual ridge resorption. Previous reports have confirmed the application of modified standard surgical techniques when shorter (Bass & Triplett 1991; Keller 1995) or wider (Langer et al. 1993) implants are placed. Wider diameter implants would provide greater implant/bone surface contact area compared with standard implants of the same length (Langer et al. 1993), reduce the stress concentration on the surrounding bone (Matsushita et al. 1990; Himmlova´ et al. 2004) and provide better stability for the prosthesis (Graves et al. 1994). Ultimately, the outcomes of implant placement in areas of compromised bone volume or density would be enhanced (Langer et al. 1993; Krennmair & Waldenberger 2004; Renouard & Nisand 2006). Higher failure rates reported with wide diameter implants in bone of poor density do not necessarily have the same relevance in the anterior mandible (Renouard & Nisand 2006). Finally, the design of the novel implant with its tapered apical configuration makes it well adapted to the anatomy of the mandibular midline as observed in the mid-sagittal section. Selection of the prosthodontic platform

Anatomical limitations on implant surgery dictated by the pattern of residual ridge resorption labially and the restriction in the midline call for specific prosthodontic planning for mandibular single-implant overdentures. When compared with mandibular two-implant overdentures, from an anatomic perspective, the bucco-lingual positioning of implants at the canine or the premolar area seems less crucial than their anterior–posterior positioning. This could be due to the fact that bone resorption mainly affects the height and, to a lesser degree, the width of the ridge at this site (Atwood 1963; Cawood & Howell

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1988). Secondly, a definite axis of rotation usually exists along a line connecting the two implants. With anterior denture teeth sitting forward of this line, unfavourable leverage occurs, causing more anterior rotation of the overdenture when incising. Placing the implants more anteriorly at the incisor region has been recommended to overcome this limitation (Taylor 2003). Conversely, with mandibular singleimplant overdentures, labiolingual positioning of the midline implant seems to be more pertinent and definite multiple axes of rotation exist. Labial inclination of a wide diameter implant can result in unfavourable tooth positioning and aesthetic limitations with encroachment on the lower lip. Lingual inclination, on the other hand, will confer lingual bulk to the overdenture with a restriction on tongue space, violating the neutral zone concept and speech. Favourable placement of the larger overdenture matrix at the centre of the undersurface of the denture base labiolingually is essential to prevent midline fracture of the overdenture (Liddelow & Henry 2007). The wide platform of the novel implant provides the foundation for the placement of a custom-designed large ball abutment (patrix) and the corresponding large plastic cap (matrix). Higher retention values have been demonstrated for larger diameter ball attachments under in vitro investigation when comparing small 2.25 mm vs. larger 3.5 mm ones (Petropoulos & Smith 2002). The platform switch concept between an 6.5 mm implant platform and a narrower 5.0 mm ball abutment base also shifts the implant–abutment microgap towards the centre of the implant (Lazzara & Porter 2006). Less marginal bone loss around implants restored with platform-switched abutments has been reported in the literature at other surgical sites in the mouth (Canullo & Rasperini 2007).

Clinical procedures Preoperative treatment planning should be carried out within a framework of minimal cost for the smallest intervention for elderly patients in both developed and developing countries. While computerized tomography and computer-designed surgical guides are undoubtedly valuable, they

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Fig. 1. (a) Open-flap procedure, midline mandibular site preparation and novel design wide diameter (8 mm) implant ready for placement. (b) Implant in situ. (c) Healing abutment placed with evidence of platform switch. (d) Flap replaced and sutured with completion of a one-stage surgical procedure.

are prohibitively costly options for the simple placement of one implant in the mandibular symphysis. Panoramic radiographs and conventional lateral cephalograms have been traditionally successful for implant placement in the anterior mandible, supported by low-cost conventional cross-sectional tomography to provide pre-operative planning by means of radiography (Mraiwa et al. 2003; Taylor 2003). A simple radiopaque marker corresponding to the labiolingual width of the mandibular denture at the midline is adapted on the undersurface, before radiographic exposure (Liddelow & Henry 2007). The surgical procedure (Fig. 1) is carried out under local anaesthesia, following premedication with 2 g amoxicillin (or 600 mg of clindamycin) and 1 g paracetamol. After two rinses with 0.2% chlorhexidine gluconate, each lasting 1 min, the labial and lingual mucosa of the anterior mandible is locally infiltrated with 2.2 ml of mepivacaine 2% with 1 : 100,000 adrenalin. A surgical guide made from the duplicated mandibular complete denture is used to mark the implant site. A 2 mm twist drill is first used to puncture the mucosa and make an indentation on the anterior mandibular ridge at the proposed midline implant site. After incising the alveolus for 15 mm either side of the mucosal puncture mark, a full-thickness mucoperiosteal flap is raised to expose the anterior mandible. Deep dissection of this flap lingually

exposes the cortical plate of the mandible and any lingual concavities (Kalpidis & Setayesh 2004; Quirynen & Lekholm 2008). The implant position is adjusted to the midline of the mandible and optimum labiolingual positioning and bone levelling is performed as necessary. A bone tap is used in bone quality types 1 and 2 (Lekholm & Zarb 1985) and primary stability is achieved with a 45 N cm torque. Early clinical experience with the current approach indicates that omitting pre-tapping of the implant site and the use of final drilling before implant placement are advisable in softer bone (type 3 Lekholm & Zarb 1985). A healing abutment is selected to be 2 mm above the mucosa. The mucosa is adjusted and sutured with interrupted sutures (4-0 Vicryl, Ethicon, Johnson & Johnson, Brussels, Belgium). Postoperatively, the patient should rinse with 0.2% chlorhexidine gluconate mouthwash for 2 weeks. Immediately following implant surgery, generous relief of the existing mandibular complete denture is carried out and a tissue conditioner (Visco-gel, Dentsply De Trey, Konstanz, Germany) is applied to the undersurface of the denture, following similar successful outcomes with mandibular two-implant overdentures (Payne et al. 2003a). The patient leaves after the surgical operation wearing both the complete maxillary denture opposed by the tissue-conditioned mandibular complete denture.

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Conclusions

Fig. 3. (a) Novel design of ball abutment patrix (5.9 mm in diameter). (b) Plastic cap matrix (7 mm diameter and 5 mm in height) within the denture base. Note the bilateral grooves to facilitate removal.

Fig. 2. (a) Post-operative panoramic radiograph of the novel design (Scanora, Soridex, Finland). (b) Lateral cephalometric radiograph of the novel design (Scanora).

The healing abutment is removed 6 weeks after surgery following an early loading protocol (Payne et al. 2003a) and replaced with the novel large ball abutment tightened to 32 N cm (Figs 2 and 3a). The height of the ball abutment is selected according to the thickness of the completely healed peri-implant mucosa. On the same day as the abutment connection, a closed-mouth reline procedure can be carried out (Impregum, Espe, Germany) to include the specially designed large plastic cap (matrix) in the undersurface of the

The review has identified limited literature on mandibular single-implant overdentures (opposing maxillary complete dentures). There is a lack of published randomized clinical trials using mandibular singleimplant overdentures, opposing maxillary complete dentures. These studies found in the review have used different loading protocols with different implant systems, but always with regular diameter implants. A novel approach using a short, wide diameter tapered implant and a custom-designed larger attachment system (incorporating a platform switch) for a mandibular single-implant overdenture is described. Without evidence from randomized clinical trials, routine use of this approach cannot be recommended.

existing mandibular denture (Fig. 3b). Alternatively, at this stage, fabrication of the new mandibular single-implant overdenture and the opposing complete maxillary denture is commenced. The labial flange is reduced bilaterally to facilitate easy removal for elderly patients with limited manual dexterity. The novel approach still does not have the supporting evidence from randomized clinical trials, compared with those using regular diameter implants and currently available attachment systems. Hence, caution is needed before recommending its routine use for elderly patients suffering from the edentulous predicament.

Acknowledgements: We acknowledge Professor Mark Stringer, Senior Lecturer, Department of Anatomy and Structural Biology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand, for his kind contributions to this article. The authors would also like to thank all the participants and staff of Oral Implantology Research Group, Sir John Walsh Research Institute, School of Dentistry, University of Otago, Dunedin, New Zealand. Finally, Southern Implants (Pty) Ltd (South Africa, Europe and United States) is acknowledged for their support in development of this novel attachment design.

Atwood, D. & Coy, W. (1971) Clinical, cephalometric and densitometric study of reduction of residual ridges. Journal of Prosthetic Dentistry 26: 810–824. Bahat, O. & Handelsman, M. (1996) Use of wide implants and double implants in the posterior jaw: a clinical report. International Journal of Oral & Maxillofacial Implants 11: 379–386. Bass, S. & Triplett, R. (1991) The effects of preoperative resorption and jaw anatomy on implant success. A report of 303 cases. Clinical Oral Implants Research 2: 193–198.

Bavitz, J.M., Harn, S.D. & Hornze, E.J. (1994) The aterial supply to the floor of the mouth and the lingual gingivae. Oral surgery, Oral Medicine, Oral Pathology 77: 232–235. Bergendal, T. & Engquist, B. (1998) Implantsupported overdentures: a longitudinal prospective study. International Journal of Oral & Maxillofacial Implants 13: 253–262. Blahout, R., Hienz, S., Solar, P., Matejka, M. & Ulm, C. (2007) Quantification of bone resorption in the interforaminal region of the atrophic mandible. International Journal of

References Anner, R., Better, H. & Chaushu, G. (2005) The clinical effectiveness of 6 mm diameter implants. Journal of Periodontology 76: 1013–1015. Attard, N. & Zarb, G. (2004) Long-term treatment outcomes in edentulous patients with implant overdentures: the Toronto study. International Journal of Prosthodontics 17: 425–433. Atwood, D. (1963) Post extraction changes in adult mandible as illustrated by microradiographs of mid-sagittal sections and serial cephalometric roentgenograms. Journal of Prosthetic Dentistry 13: 810–824.

 c 2009 The Authors. Journal compilation  c 2009 John Wiley & Sons A/S

363 |

Clin. Oral Impl. Res. 20, 2009 / 356–365

Alsabeeha et al . Mandibular single implant overdentures

Oral & Maxillofacial Implants 22: 609–615. Boyes-Varley, J.G. & Lownie, J.F. (2002) Haematoma of the floor of the mouth following implant placement. South African Dental Journal 57: 64–65. Branemark, P.I., Svensson, B. & van Steenberghe, D. (1995) Ten-year survival rates of fixed prostheses on four or six implants ad modum Branemark in full edentulism. Clinical Oral Implants Research 6: 227–231. Buser, D. & Maeglin, B. (1996) Surgical procedures with ITI implants. In: Schroeder, A., Sutter, F., Buser, D. & Krekeler, G., eds. Oral Implantology: Basics, ITI Hollow Cylinder System, 256–296. Stuttgart: Thieme Medical Publishers Inc. Canullo, L. & Rasperini, G. (2007) Preservation of peri-implant soft and hard tissues using platform switching of implants placed in immediate extraction sockets: a proof-of-concept study with 12- to 36-month follow-up. International Journal of Oral & Maxillofacial Implants 22: 995–1000. Carlsson, G. (2003) Future directions. In: Feine, J. & Carlsson, G., eds. Implant Overdentures: The Standard of Care for the Edentulous Patients, 145–154. Chicago, IL: Quintessence Publishing Co. Inc. Carlsson, G., Kronstrom, M., de Baat, C., Cune, M., Davis, D., Garefis, P., Heo, S.J., Jokstad, A., Matsuura, M., Narhi, T., Ow, R., Pissiotis, A., Sato, H. & Zarb, G. (2004) A survey of the use of mandibular implant overdentures in 10 countries. International Journal of Prosthodontics 17: 211–217. Cawood, J. & Howell, R. (1988) A classification of the edentulous jaws. International Journal of Oral and Maxillofacial Surgery 17: 211–217. Cordioli, G., Majzoub, Z. & Castagna, S. (1997) Mandibular overdentures anchored to single implants: a five year prospective study. Journal of Prosthetic Dentistry 78: 159–165. Davis, D. & Packer, M. (1999) Mandibular overdentures stabilized by Astra tech implants with either ball attachments or magnets: 5-year results. International Journal of Prosthodontics 12: 222–229. Denissen, H., Veldhuis, H. & van Faassen, F. (1984) Implant placement in the atrophic mandible: an anatomic study. Journal of Prosthetic Dentistry 52: 260–263. Engquist, B., Bergendal, T., Kallus, T. & Linden, U. (1988) A retrospective multicenter evaluation of osseointegrated implants supporting overdentures. International Journal of Oral & Maxillofacial Implants 3: 129–134. Enlow, D. (1976) The remodeling of the edentulous mandible. Journal of Prosthetic Dentistry 36: 685–693. Eriksson, RA. & Adell, R. (1986) Temperatures during drilling for the placement of implants using the osseointegration technique. International Journal of Oral and Maxillofacial Surgery 44: 4–7. Feine, J., Carlsson, G., Awad, M., Chehade, A., Duncan, W., Gizani, S., Head, T., Lund, J., MacEntee, M., Mericske-Stern, R., Mojon, P., Morais, J., Naert, I., Payne, A., Penrod, J., Stoker,

364 |

Clin. Oral Impl. Res. 20, 2009 / 356–365

G.J., Tawse-Smith, A., Taylor, T., Thomason, J., Thomson, W. & Wismeijer, D. (2002) The McGill consensus statement on overdentures. International Journal of Prosthodontics 15: 413–414. Fitzpatrick, B. (2006) Standard of care for the edentulous mandible: a systematic review. Journal of Prosthetic Dentistry 95: 71–78. Friberg, B., Grondahl, K., Lekholm, U. & Branemark, P.I. (2000) Long-term follow-up of severely atrophic edentulous mandibles reconstructed with short Branemark implants. Clinical Implant Dentistry & Related Research 2: 184–189. Friberg, B., Jemt, T. & Lekholm, U. (1991) Early failures in 4,641 consecutively placed Bra˚nemark dental implants: a study from stage 1 surgery to the connection of completed prostheses. International Journal of Oral & Maxillofacial Implants 6: 142–146. Geertman, M., Boerrigter, E., Van Waas, M. & vanOort, R.P. (1996) Clinical aspects of a multicenter clinical trial of implant-retained mandibular overdentures in patients with severely resorbed mandibles. Journal of Prosthetic Dentistry 75: 194–204. Graves, S., Jansen, C., Siddiqui, A. & Beaty, K. (1994) Wide diameter implants: indications, considerations and preliminary results over a twoyear period. Australian Prosthodontic Journal 8: 31–37. Himmlova´, L., Dosta´lova´, T., Ka´covsky´, A. & Konvickova´, S. (2004) Influence of implant length and diameter on stress distribution: a finite element analysis. Journal of Prosthetic Dentistry 91: 20–25. Hofschneider, U., Tepper, G., Gahleitner, A. & Ulm, C. (1999) Assessment of the blood supply to the mental region for reduction of bleeding complications during implant surgery in the interforaminal region. International Journal of Oral & Maxillofacial Implants 14: 379–383. Ivanoff, C., Gro¨ndahl, K., Sennerby, L., Bergstro¨m, C. & Lekholm, U. (1999) Influence of variations in implant diameters: a 3- to 5-year retrospective clinical report. International Journal of Oral & Maxillofacial Implants 14: 173–180. Jacobson, T. & Krol, A. (1983a) A contemporary review of the factors involved in complete denture retention, stability, and support. Part 1: retention. Journal of Prosthetic Dentistry 49: 5–15. Jacobson, T. & Krol, A. (1983b) A contemporary review of the factors involved in complete dentures. Part 2: stability. Journal of Prosthetic Dentistry 49: 165–172. Jacobson, T. & Krol, A. (1983c) A contemporary review of the factors involved in complete dentures. Part 3: support. Journal of Prosthetic Dentistry 49: 306–313. Jemt, T., Chai, J., Harnett, J., Heath, M., Hutton, J., Johns, R., McKenna, S., McNamara, D., van Steenberghe, D., Taylor, R., Watson, R. & Herrmann, I. (1996) A 5-year prospective multicenter follow-up report on overdentures supported by osseointegrated implants. International Journal of Oral & Maxillofacial Implants 11: 291–298. Kalpidis, C.D. & Setayesh, R.M. (2004) Hemorrhaging associated with endosseous implant place-

ment in the anterior mandible: a review of the literature. Journal of Periodontology 75: 631–645. Keller, E. (1995) Reconstruction of the severely atrophic edentulous mandible with endosseous implants: a 10-year longitudinal study. Journal of Oral and Maxillofacial Surgery 53: 305–320. Khayat, P., Hallage, P. & Toledo, R. (2001) An investigation of 131 consecutively placed wide screw-vent implants. International Journal of Oral & Maxillofacial Implants 16: 827–832. Klemetti, E. (2008) Is there a minimum number of implants to retain an overdenture? Journal of Oral Rehabilitation 35 (Suppl.): 80–84. Krennmair, G. & Ulm, C. (2001) The symphyseal single-tooth implant for anchorage of a mandibular complete denture in geriatric patients: a clinical report. International Journal of Oral & Maxillofacial Implants 16: 98–104. Krennmair, G. & Waldenberger, O. (2004) Clinical analysis of wide-diameter Frialit-2 implants. International Journal of Oral & Maxillofacial Implants 19: 710–715. Kronstrom, M., Davis, B., Loney, R. & Gerrow, J. (2007) Mandibular overdentures supported by one or two unsplinted implants using the immediate loading protocol (Abstract). International College of Prosthodontics Meeting, September 2007, Fukuoka, Japan. Laboda, G. (1990) Life-threatening hemorrhage after placement of an endosseous implant: report of a case. Journal of American Dental Association 121: 599–600. Langer, B., Langer, L., Herrmann, I. & Jorneus, L. (1993) The wide fixture: a solution for special bone situations and a rescue for the compromised implant. Part 1. International Journal of Oral & Maxillofacial Implants 8: 400–408. Lazzara, R. & Porter, S. (2006) Platform switching: a new concept in implant dentistry for controlling post-restorative crestal bone levels. International Journal of Periodontics and Restorative Dentistry 26: 9–17. Ledermann, P.D. (1983) Sechsjahrige klinische Erfahrung mit dem titanplasmabeschichteten, ITI-Schraubenimplantat in der Regio Interforaminalis des Unterkiefers. Schweiz Monatsschr Zahnmed 93: 1080–1089. Lekholm, U. & Zarb, G. (1985) Patient selection and preparation. In: Branemark, P., Zarb, G. & Albrektsson, T., eds. Osseointegration in Clinical Dentistry, 199–209. Chicago, IL: Quintessence Publishing Co. Inc. Liddelow, G.J. & Henry, P.J. (2007) A prospective study of immediately loaded single implant-retained mandibular overdentures: preliminary oneyear results. Journal of Prosthetic Dentistry 97: S126–S137. MacEntee, M. & Walton, J. (2007) A randomized trial of one and two endosseous implants in the mandible (Abstract). International College of Prosthodontics Meeting, September 2007, Fukuoka, Japan. Mansong-Hing, L.R. (1990) Fundamentals of Dental Radiography. 3rd edition, 242–249. Philadelphia: Lea & Febiger. Marzola, R., Scotti, R., Fazi, G. & Schincaglia, G. (2007) Immediate loading of two implants support-

 c 2009 The Authors. Journal compilation  c 2009 John Wiley & Sons A/S

Alsabeeha et al . Mandibular single implant overdentures

ing a ball attachment-retained mandibular overdenture: a prospective clinical study. Clinical Implant Dentistry & Related Research 9: 136–143. Mason, M.E., Triplett, R.G. & Alfonso, I.V.F. (1990) Life-threatening hemorrhage after placement of a dental implant. Journal of Oral and Maxillofacial Surgery 48: 201–204. Matsushita, Y., Kitoh, M., Mizuta, K., Ikeda, H. & Suetsugu, T. (1990) Two-dimensional fem analysis of hydroxyapatite implants: diameter effects on stress distribution. Journal of Oral Implantology 16: 6–11. McDonnell, D., Nouri, M. & Todd, M. (1994) The mandibular lingual foramin: a consistent arterial foramen in the middle of the mandible. Journal of Anatomy 184: 363–369. McGarry, T., Nimmo, A., Skiba, J., Ahlstrom, R., Smith, C. & Koumjian, J. (1999) Classification system for complete edentulism. Journal of Prosthodontics 8: 27–39. Meijer, H., Raghoebar, G. & Van’t Hof, M. (2003) Comparison of implant-retained mandibular overdentures and conventional complete dentures: a 10-year prospective study of clinical aspects and patient satisfaction. International Journal of Oral & Maxillofacial Implants 18: 879–885. Mericske-Stern, R. (1996) Overdentures supported by ITI implants. In: Schroeder, A., Sutter, F. & Krekeler, G., et al., eds. Oral Implantology: Basics, ITI Hollow Cylinder System. 2nd revised edition, 349–358. Stuttgart: G. Thieme Medical Publishers. Mraiwa, N., Jacob, R., van Steenberghe, D. & Quirynen, M. (2003) Clinical assessment and surgical implications of anatomic challenges in the anterior mandible. Clinical Implant Dentistry & Related Research 5: 219–225. Naert, I., Alsaadi, G., van Steenberghe, D. & Quirynen, M. (2004) A 10-year randomized clinical trial on the influence of splinted and unsplinted oral implants retaining mandibular overdentures: peri-implant outcome. International Journal of Oral & Maxillofacial Implants 19: 695–702. Niamtu, J. (2001) Near fatal airway obstruction after routine implant placement. Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, Endodontics 92: 597–600. Owen, P. (2004) Appropriatech: prosthodontics for the many not just for the few. International Journal of Prosthodontics 17: 261–262. Payne, A., Tawse-Smith, A., Thompson, W. & Kumara, R. (2003b) Early functional loading of unsplinted roughened surface implants with mandibular overdentures 2 weeks after surgery. Clinical Implant Dentistry & Related Research 5: 143–153. Payne, A.G.T., Tawse-Smith, A., Duncan, W.J. & Thomson, W.M. (2003a) Loading strategies for implant overdentures. In: Feine, J.F. & Carlsson, G., eds. Implant Overdentures: The Standard of Care for the Edentulous Patients, 111–128. Chicago, IL: Quintessence Publishing Co. Inc. Petropoulos, V. & Smith, W. (2002) Maximum dislodging forces of implant overdenture stud attachments. International Journal of Oral & Maxillofacial Implants 17: 526–535.

Quirynen, M. & Lekholm, U. (2008) The surgical site. In: Lindhe, J., Lang, N.P. & Karring, T., eds. Clinical Periodontology and Implant Dentistry. 5th edition, 1071–1073. Singapore: Blackwell Publishing Ltd. Renouard, F. & Nisand, N. (2006) Impact of implant length and diameter on survival rate. Clinical Oral Implants Research 17: 35–51. Romeo, E., Ghisolfi, M. & Rozza, R. (2006) Short (8-mm) dental implants in the rehabilitation of partial and complete edentulism: a 3- to 14-year longitudinal study. International Journal of Prosthodontics 19: 586–592. Shin, S., Bryant, S. & Zarb, G. (2004) A retrospective study on the treatment outcome of wide-bodied implants. International Journal of Prosthodontics 17: 52–58. Spiekermann, H., Jansen, V. & Richter, E. (1995) A 10-year follow-up study of IMZ and TPS implants in the edentulous mandible using bar-retained overdentures. International Journal of Oral & Maxillofacial Implants 10: 231–243. Stalblad, P.A., Jansson, T., Jemt, T. & Zarb, G. (1985) Osseointegration in overdenture therapy. Preliminary comments. Swedish Dental Journal Supplement 28: 169–170. Standring, S. (2005) The anatomical basis of clinical practice. In: Standring, S., eds. Grays Anatomy. 39th edition, 546, 587. New York, USA: Elsevier, Churchill Livingstone. Stellingsma, C., Meijer, H. & Raghoebar, G. (2000) Use of short endosseous implants and an overdenture in the extremely resorbed mandible: a five-year retrospective study. Journal of Oral and Maxillofacial Surgery 58: 382–387. Takanashi, Y., Penrod, J.R., Lund, J.P. & Feine, J.S. (2004) A cost-comparison of mandibular two-implant overdentures and conventional denture treatment. International Journal of Prosthodontics 17: 181–186. Tallgren, A. (1972) The continuing reduction of the residual alveolar ridges in complete denture wearers: a mixed-longitudinal study covering 25 years. Journal of Prosthetic Dentistry 27: 120–132. Tawse-Smith, A., Payne, A.G.T., Kumara, R. & Thomson, W. (2001) One-stage operative procedure using two different implant systems: a prospective study on implant overdentures in the edentulous mandible. Clinical Implant Dentistry & Related Research 3: 185–193. Tawse-Smith, A., Payne, A.G.T., Kumara, R. & Thomson, W. (2002) Early loading of unsplinted implants supporting mandibular overdentures using a one-stage operative procedure with two different implant systems: a 2-year report. Clinical Implant Dentistry & Related Research 4: 33–42. Taylor, T.D. (2003) Indications and treatment planning for mandibular implant overdentures. In: Feine, J. & Carlsson, G., eds. Implant Overdentures: The Standard of Care for the Edentulous Patients, 71–82. Chicago, IL: Quintessence Publishing Co. Inc. ten Bruggenkate, C.M., Asikainen, P., Foitzik, C., Krekeler, G. & Sutter, F. (1998) Short (6-mm) nonsubmerged dental implants: results of a multicenter clinical trial of 1 to 7 years. International Journal of Oral & Maxillofacial Implants 13: 791–798.

 c 2009 The Authors. Journal compilation  c 2009 John Wiley & Sons A/S

ten Bruggenkate, C.M., Krekeler, G., Kraaijenhagen, H.A., Foitzik, C. & Oosterbeek, H.S. (1993) Haemorrhage of the floor of the mouth resulting from lingual perforation during implant placement: a clinical report. International Journal of Oral & Maxillofacial Implants 8: 329–334. Tepper, G., Hofschneider, U., Gahleitner, A. & Ulm, C. (2001) Computed tomographic diagnosis and localization of bone canals in the mandibular interforaminal region for prevention of bleeding complications during implant surgery. International Journal of Oral & Maxillofacial Implants 16: 68–72. van den Bergh, J., ten Bruggenkate, C. & Tuinzing, D. (1998) Preimplant surgery of the bony tissues. Journal of Prosthetic Dentistry 80: 175–183. Visser, A., Meijer, H., Raghoebar, G. & Vissink, A. (2006) Implant-retained mandibular overdentures versus conventional dentures: a 10 years of care and aftercare. International Journal of Prosthodontics 19: 271–278. Walton, J. & MacEntee, M. (2008) Results with overdentures retained by one or two implants. Journal of Dental Research (Special Issue), abstract #103253. Watson, G., Payne, A., Purton, D. & Thomson, W. (2002) Mandibular overdentures: comparative evaluation of prosthodontic maintenance of 3 difference implant systems during the first year of sevice. International Journal of Prosthodontics 15: 259–266. Wolfart, S., Braasch, K., Brunzel, S. & Kern, M. (2008) The central single implant in the edentulous mandible: improvement in function and quality of life – a report of 2 cases. Quintessence International 39: 541–548. Woo, B., Al-Bustani, S. & Ueeck, B. (2006) Floor of mouth haemorrhage and life-threatening airway obstruction during immediate implant placement in the anterior mandible. International Journal of Oral and Maxillofacial Surgery 35: 91–94. Worthington, P. (1992) Clinical aspects of severe mandibular atrophy. In: Worthington, P. & Branemark, P-I., eds. Advanced Osseointegration Surgery: Applications in the Maxillofacial Region, 119–122. Chicago, IL: Quintessence Publishing Co. Inc. Zarb, G.A. (2004) The edentulous predicament. In: Zarb, G.A., Bolender, C.L., Eckert, S.E., Jacob, R.F., Fenton, A.H. & Mericske-Stern, R., eds. Prosthodontic Treatment for Edentulous Patients. Complete Dentures and Implant-Supported Prostheses. 12th edition, 3–5. St. Louis: Mosby. Zarb, G.A. (2005) Meetings and a goodbye. Editorial. International Journal of Prosthodontics 18: 365–367. Zarb, G.A. & Bolender, C.L. (2004) Biomechanics of the edentulous state. In: Zarb, G.A., Bolender, C.L., Eckert, S.E., Jacob, R.F., Fenton, A.H. & Mericske-Stern, R., eds. Prosthodontic Treatment for Edentulous Patients. Complete Dentures and Implant-Supported Prostheses. 12th edition, 6–23. St. Louis: Mosby. Zarb, G.A., Jansson, T. & Jemt, T. (1985) Other prosthodontic applications. In: Branemark, P.I., Zarb, G.A. & Albrektsson, T., eds. Tissue-Integrated Prostheses: Osseointegration in Clinical Dentistry, 283–292. Chicago, IL: Quintessence Publishing Co. Inc.

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Clin. Oral Impl. Res. 20, 2009 / 356–365