The International Journal of Oral & Maxillofacial Implants, 03/2004

The Academy of Osseointegration (AO) and its foundation recently completed a successful reorganization of the foundation and a renewal of our relationship. This reorganization was designed to bring both organizations closer together so that they can function in concert with each other. The organization and its foundation had drifted apart in recent years. The roots of this problem dated back to the creation of the foundation several years ago. The recent problems were simply a reflection of the lack of direction created by inadequate planning at the time the foundation was created. This is similar to the problems that occur when a complex surgical or restorative case is started without a fully developed treatment plan. The reorganization process that the AO undertook was lengthy and at times contentious. In the end, the leaders of both organizations worked together to create the new relationship. The result will be a foundation that the members of the Academy and the past and present board members of the foundation will be proud of.

Purpose: The authors evaluated, under conditions simulating implant placement, the cutting efficiency, durability, heat production, and wear of implant drills. Materials and Methods: Osteotomies were performed on bovine ribs using a surgical unit mounted in a testing apparatus. A software program controlled the apparatus and recorded temperatures, depths, and drilling times. Seven brands of drills were tested (Nobel Biocare, 3i/Implant Innovations, Steri-Oss, Paragon, Implamed, Lifecore, and ITI). Spade, twist, tri-flute, and TiN-coated drill designs were evaluated and compared during 100 successive osteotomies. Scanning electron microscopic and energy-dispersive x-ray spectroscopic examinations were performed, and hardness was measured. Results: Two 2-mm drills (Nobel Biocare and 3i/Implant Innovations) had mean removal rates significantly greater than the others (P .05). The 2- mm twist drill design with a low hardness (Implamed) exhibited plastic deformation at the cutting edge, loss of cutting efficiency, and drill fracture. The TiN-coated drills (Steri-Oss and Paragon) showed greater wear and significantly lower removal rates (P .05) than noncoated drills. Temperature increases with different drills were not significantly different at depths of 5 or 15 mm or between 2- mm or 3-mm drills. With 1 exception (the 2.3-mm Paragon drill at a depth of 15 mm), the temperatures generated by the different types of drills were not significantly different. Clinically harmful temperatures were detected only at a depth of 15 mm during 5 osteotomies and coincided with a marked decrease in the rate of drill advancement with a resulting continuous drilling action. Discussion: Temperatures generated at depths of 5 and 15 mm by the different drill types and diameters were not significantly different and, with only 5 exceptions, were clinically safe. Several differences between brands were noted in regard to cutting efficiency and durability, underscoring the importance of material selection and quality on drill performance. Conclusions: Drill design, material, and mechanical properties significantly affect cutting efficiency and durability. Coolant availability and temperature were the predominant factors in determining bone temperatures. Implant drills can be used several times without resulting in bone temperatures that are potentially harmful. Continuous drilling in deep osteotomies can produce local temperatures that might be harmful to the bone.

Purpose: The purpose of this study was to compare machined-surface implants (control) and oxidizedsurface titanium screw-type implants (test) loaded with fixed partial dentures at 2, 4, and 6 weeks postplacement in terms of implant survival and stability. Materials and Methods: The beagle model was chosen for the study. Four mandibular premolars were extracted bilaterally from each dog. After 2 months of healing, 4 implants were placed in each dog. HaIf of the dogs (n = 6), the test group, received oxidized-surface implants; the other half (n = 6), the control group, received machined-surface implants. In each group, 2 dogs were randomly assigned to a 2-week preloading healing period, 2 to a 4-week period, and 2 to a 6-week period. Three implants were loaded in each dog; 1 was left unloaded as a control. Clinical stability and survival were monitored every 2 weeks for 6 months. Results: Failures were noted only among the implants assigned to the 2- and 4-week groups. Failures accounted for 9.4% (9/96) of the implants-12.5% (6/48) of the control implants and 6.3% (3/48) of the test implants. One hundred percent prosthesis stability was noted for the test-surface implant group. Stability of the test implants was significantly better than stability of the control implants (-2.6 vs -1.7, P .05). Mean Periotest values at loading were 3.7 for the group loaded at 2 weeks, 1.6 for the group loaded at 4 weeks, and 0.6 for the group loaded at 6 weeks. Fifty percent of the 6-week group, 25% of the 4-week group, and 12.5% of the 2-week group had a Periotest value 0 at loading. Discussion: The results reveal a qualitative difference in performance between the implant groups. Twice as many failures occurred in the control group, few failures occurred following loading, and no failures occurred after 4 weeks postplacement. The survival curves for both implants were flat after 4 weeks; however, the duration of follow-up may hide effects of time-dependent factors on survival and poses a concern for clinical inference. Conclusions: Early loading of both implant types was well tolerated, as only 2 failures occurred following loading. A subsequent report will review these outcomes along with histomorphometric data collected at 6 months to better understand the significance of tissue- level implant-surface interaction for survival and stability.

Purpose: An inorganic xenograft (inorganic bovine bone [IBB]) and a porous alloplast ( ß-tricalcium phosphate [ ß-TCP]) material were compared at different healing periods in experimental bone defects in dogs. Materials and Methods: Six round defects, 5 × 4 mm, were made on the lateral bony mandibular angle in 8 dogs at different times. Two defects were randomly filled with IBB, 2 with ß-TCP, and 2 were left to blood clot. A bi-layer collagen membrane covered 1 defect of each type. Four specimens per treatment group were obtained for each treatment group at 3, 6, 12, and 24 months postoperatively. Morphometric analysis of decalcified (Donath technique) histologic slides was conducted using the measured areas of regenerated bone, grafted particles, and remaining concavity. Results: In IBB sites, complete bone healing was evident at 12 and 24 months, but grafted particles dominated the sites. In ß-TCP sites, only particle remnants remained at 12 months. At 24 months, particles had completely resorbed in both membrane-protected (MP) and uncovered (UC) defects. Data were combined for final analysis since there were no statistically significant differences within each graft material group (MP or UC). Mean bone area fraction increased from 3 to 24 months at all sites. In bone area fraction a statistically significant difference was found between 3 and 6 months in the IBB and ß-TCP groups. IBB sites also showed such significance between 6 and 12 months. A statistically significant difference was found between MP ungrafted sites (42.9%) vs IBB (24.7%) and vs the control (24.8%) at 3 months. At 6 months, ß-TCP bone area fraction (68.8%) was significantly greater than IBB (47.9%) and control (37.5%) sites. At 12 months, ß-TCP bone area fraction (79.0%) was significantly greater than the control (42.5%). At 24 months, ß- TCP bone area fraction (86.5%) was significantly greater than IBB (55.6%) sites. Mean particle area fraction of ß-TCP sites decreased gradually until complete resorption at 24 months. IBB sites showed a significant decrease only between 3 (38.7%) and 6 (29.4%) months. Discussion and Conclusion: Complete bone healing was established in all grafted defects. IBB and ß-TCP are both excellent biocompatible materials. However, at 24 months ß-TCP particles were completely resorbed, whereas IBB particles still occupied a remarkable area fraction without significant resorption beyond 6 months. (More than 50 references.)

Purpose: To compare the incidence of complications related to onlay bone grafts (OBGs) and sinus lift operations (SLOs) among smokers and nonsmokers. Materials and Methods: Data from 143 operations performed during the years 1995 to 2003 were analyzed. There were 64 OBGs and 79 SLOs. Patients were divided into 3 groups: nonsmokers, mild smokers (up to 10 cigarettes per day), and heavy smokers (more than 10 cigarettes per day). Duration of smoking (less or more than 10 years) was recorded. OBG complications were classified as minor (hematoma, swelling, inflammation, or temporary paresthesia) or major (graft exposure or mobility). For the SLO, perforations of the schneiderian membrane were the main intraoperative complication; postoperative complications mostly consisted of swelling, acute or chronic sinus infection, or bleeding. Results: Of smokers having OBG, 50% experienced complications, compared to 23.1% of nonsmokers. Major complications were observed in one third of the smokers, compared to only 7.7% in nonsmokers. There was also a tendency toward complications in former smokers, although this relationship was not statistically significant. There was no relationship between SLO complications and smoking or a past smoking habit. Discussion: In the present study, smokers demonstrated significantly higher postoperative complications following OBG operations. Smoking did not influence the results in the SLO group. There was no statistically significant difference between complications and past smoking. This finding indicates that the risk of complications can be reduced up to the normal nonsmoker complication rate when smoking ceases. Conclusions: This study established a relationship between OBG complications and smoking in this patient population. A higher incidence of complications was found in the smoking group. There was no significant influence of smoking on SLO complications.

Purpose: This prospective, randomized study investigated the safety, feasibility, and reliability of the early loading of implants in edentulous maxillae. Materials and Methods: Twenty-four patients with completely edentulous maxillae were randomized into a test group (n = 16) and a control group (n = 8). All patients received 5 or 6 solid screw-type titanium implants. These were loaded with full-arch prostheses after 9 to 18 days in the test group and after 2.5 to 5.1 months in the control group. Periapical radiographs were taken and routine clinical assessments were made at loading, after 6 months, and after 12 months. Results: The implant survival rate 1 year after loading was 100%. Modified Plaque Index scores and Sulcus Bleeding Index scores were better in the test group than in the control group (P = .05). There was a significant difference in peri-implant bone height between the 2 groups (P .001) and this difference converged with time (P .001). Discussion: This clinical, prospective, randomized, controlled study fulfilled the criteria for a comparable study. Owing to the small patient sample, the conclusions drawn were based on feasibility analyses of the results. Standard materials and methods were used. Only patients with maxillary bone of sufficient height and width were selected. The use of a single operator in each discipline-maxillofacial surgery, prosthodontics, and dental technology -may have improved the chances of achieving consistent standards and opinions. Conclusion: These results indicate that early loading in selected patients was as safe and reliable as delayed loading in this small patient population and may offer a satisfactory alternative to the standard protocol.

Purpose: In recent years, the growing readiness on the part of dental patients to take legal action has resulted in an increasing number of medical liability lawsuits. The aim of this retrospective analysis was to highlight aspects of these lawsuits of special significance, to subject them to both qualitative and quantitative analysis, and to show how conflicts can be avoided. Materials and Methods: Forty relevant court decisions from the year 1984 onwards were found in online databases and through direct inquiries at the courts. These were supplemented by 21 reports prepared by experts at the University of Muenster, Department of Dental Medicine, commissioned by courts in connection with ongoing lawsuits. Analysis was initially based on formal aspects of the cases and reports. It was later supplemented by differentiated assignment of the questions addressed by the courts to the expert consultants. The principles underlying the judgments as to the liability arising from the terms of the contract were also assigned to the expert consultants in a differentiated manner. Results: The results revealed marked differences in the frequency of liability-prone aspects of treatment. While the majority of judgments referred to the obligation to take due care during the preparatory and treatment phases, infringement of the obligations to provide information and to keep records played more than a minor role. Moreover, 90% of all cases represented combined charges covering various aspects, including those related to consequential failings. Discussion and Conclusion: The detailed qualitative analysis of the grounds quoted and of the lines of reasoning can therefore be summed up in clearly defined recommendations aimed at helping the clinician avoid conflicts by observing the judicial requirements.

Purpose: The purpose of this study was to examine retrospectively the outcome of wide-diameter dental implants used to retain fixed restorations in the posterior segments of the maxilla and mandible. Materials and Methods: Fifty-two patients were consecutively treated between 1997 and 2000 with 78 Wide-Platform (WP) Mk II implants in the posterior regions of the maxilla and/or mandible. All treated patients were called for a retrospective examination between September and November 2001. At the examination, data regarding general health and clinical and radiographic parameters were collected according to a strict protocol. Thirty-four women and 18 men with a mean age of 55 years (range 19 to 81 years) participated. Twenty-three WP implants were placed in the maxilla and 55 in the mandible. The mean time in situ was 33 months (range of 11 to 58 months). Results: Of 78 implants, 8 had been lost by the time of reexamination. Five women lost 1 implant each in the maxilla, and 2 men lost 3 implants in the mandible. The survival rate was 89.8%. Discussion: The results are encouraging because the WP implants were placed in rather unfavorable situations (generally poor bone quality, compromised bone volume, and larger occlusal forces). Conclusion: Based on the reported survival rate, wide-diameter implants present an acceptable treatment alternative.

Purpose: The purpose of this study was to investigate the cumulative survival rates of dental implants placed in a private periodontal practice and the effects of periodontal disease and immediate placement on implant survival. Materials and Methods: A retrospective chart review was conducted on 149 consecutive patients. Each patient had a single implant placed. For the purpose of analysis, patients were divided into 2 groups: those who were periodontally healthy and those who had periodontal disease. Implants were placed into available bone either immediately or after a healing period. All failed implants were removed and recorded. The effects of periodontal status and placement time on implant survival were evaluated using Cox proportional hazards regression and log-rank tests. Results: Of the 149 implants in the study, 22 failed during the observation period. The 127 censored cases (ie, implants that had not failed at the end of the observational period) were observed for a mean of 943 days (SD 932, range 35 to 4,030). Failed implants were observed for a mean of 722 days (SD 1,026, range 18 to 3,548). The presence of periodontal disease appeared to be associated with a greater failure rate, but there was no observed effect associated with time of placement. The percentages of censored immediate placement cases and delayed placement cases were nearly identical. Among the 77 implants associated with periodontal disease, placement time was not strongly associated with percentage censored. Forty-three of the 55 immediately placed implants (78.18%) and 18 of the 22 implants (81.18%) whose placement was delayed were censored. Both Cox proportional hazards regression and log-rank tests established that survival was adversely affected by periodontal disease (P .05) but unaffected by time of placement (P > .50). The lower 1-sided 95% confidence limit for median survival time was 3,548 days for patients without periodontal disease and 1,799 days for patients with disease. Discussion and Conclusion: Implant survival was compromised by a history of periodontitis but not affected by immediate or delayed placement.

Purpose: The purposes of this prospective multicenter study were to evaluate the use of vertical distraction osteogenesis in the correction of vertically deficient alveolar ridges and to evaluate whether the vertical bone gained by distraction osteogenesis was maintained over time when dental implants were placed in the distracted areas. Materials and Methods: Thirty-seven patients presenting vertically deficient edentulous ridges were treated in 4 different centers by means of distraction osteogenesis with an intraoral alveolar distractor. Two to 3 months after consolidation of the distracted segments, 138 dental implants were placed in the distracted areas. Four to 6 months later, abutments were connected and prosthetic loading of the implants began. Results: The mean follow-up after initial prosthetic loading was 34 months (range 15 to 55 months). The mean bone gain obtained by distraction was 9.9 mm (range 4 to 15 mm). The cumulative success rate of the implants 4 years after the onset of prosthetic loading was 94.2%, while the implants' cumulative survival rate was 100%. No statistically significant differences were found between the different centers as far as survival and success rates of implants were concerned. Discussion and Conclusion: The results of this study appear to demonstrate that distraction osteogenesis is a reliable technique for the correction of vertically deficient edentulous ridges. The regenerated bone appeared to withstand the functional demands of implant loading. The survival and success rates of the implants placed in the distracted areas were consistent with those reported in the literature regarding implants placed in native bone in this patient population.

Purpose: To evaluate the success and failure rates over time of ITI implants placed in 3 private practices and used in a variety of clinical situations. Materials and Methods: ITI solid-screw implants (n = 5,526) were placed in 3 private practices and restored by a variety of clinicians. Numerous clinical scenarios were treated with the implants, which were in function for between 0 and 72+ months. Results: After 72+ months the cumulative success rates were 94.8% for maxillary implants and 97.5% for mandibular implants. The overall cumulative implant success rate was 96.1%. Implants that failed to osseointegrate were included in the data as failures in the 0- to 12-month interval. The criteria of Albrektsson and associates were used to assess implant success or failure. Discussion: The results, which were achieved in conjunction with numerous restorative clinicians, were comparable to those reported by other authors. The clinical viability of ITI implant use was thus reinforced. Conclusion: ITI solid-screw implants were a predictable treatment modality in 3 private practices for a variety of clinical applications.

Purpose: The purpose of this study was to evaluate the results of the repair of perforated sinus membranes with resorbable collagen membrane. Materials and Methods: A split-mouth design was followed. Twelve subjects requiring bilateral sinus grafting were included in the study; one site had been accidentally perforated during sinus augmentation and the other site had not been perforated. The perforated sites were repaired with a resorbable collagen membrane. Dental implants were placed during a second surgery, and biopsy samples were harvested from both sinuses during implant placement. New bone formation was measured for all sites. Implant survival was recorded at second-stage surgery. Panoramic radiographs were taken before and after sinus grafting and after implant placement. Results: Nonperforated sites demonstrated significantly more bone formation (33.58% ± 7.45%) than perforated sites (14.17% ± 7.06%) (P .0001). Perforated sites demonstrated significantly more soft tissue formation (63.58% ± 12.96%) than nonperforated sites (48.5% ± 12.57%) (P = .006). In nonperforated sites, residual graft particles had more of their surface in contact with bone (40.17% ± 14.92%) than perforated sites (14.5% ± 12.03%) (P .0001). The implant survival rate at secondstage surgery was superior for nonperforated sites (100%) in comparison to perforated sites (69.56%) (P = .0028). Discussion: This study suggested that repairing the perforated site of the sinus membrane with a resorbable collagen membrane may result in reduced bone formation and implant survival rate. A different technique and/or materials than those used in the current study may offer better results for the repair of the perforated sinus membrane. Conclusion: The study demonstrated that perforation and repair of the sinus membrane may compromise new bone formation and implant survival.

The Brånemark Novum protocol for immediate functional loading of a mandibular fixed implant-supported prosthesis has been an effective alternative for selected patients. In the event of the loss of an implant, a rescue set that allows continuous use of the original fixed restoration while restoring tripod osseointegrated support at the implant level is available.

Human immunodeficiency virus (HIV) causes an immune incompetence that weakens the body's defense against pathogens. It has been supposed that HIV-positive patients are more likely to develop both early and late postoperative complications, such as septicemia and poor wound healing. This has not been corroborated by more recent studies but seems to depend on the patient's level of CD4 cells and his or her general condition. As the life expectancy of HIV-positive individuals increases and the condition becomes increasingly controllable, esthetic dental treatment becomes more significant and implant-supported prostheses may be considered as an alternative to removable dentures. Except for a single case report on the immediate placement of a single-tooth implant, no reports are available on implant dentistry in HIV-positive patients. This case report concerns implant placement in the maxilla and mandible of an HIV-positive individual and complete dental and implant rehabilitation. Two years after implant placement, the prosthesis is functioning well.

In the atrophic posterior maxilla, placement of longer (at least 10 mm) and wider diameter implants may significantly improve long-term results, but sinus grafting is often necessary to provide sufficient bone volume for implant support. The crestal approach to sinus augmentation requires penetration of the sinus floor with surgical instruments that are often difficult to control; there is a high risk of damaging the schneiderian membrane. Fabricating a round cutting rim at the apical end of a single-stage tapered implant can provide a controlled method of gently penetrating the sinus floor prior to grafting and placement of the definitive implant. In soft type 4 bone, the single-stage tapered implant design can help to enhance initial stabilization through lateral osteocondensation of the receptor site. Localized sinus elevation with osteocompression utilizing single-stage tapered implants may offer a simplified approach to the complex clinical challenge of successfully restoring the atrophic posterior maxilla.

In the absence of adequate bone height, augmentation of the maxillary antrum prior to placement of endosseous implants is a well-established procedure. Although there is a debate among clinicians as to which grafting materials are the most advantageous, autogenous bone is still considered by many to be the gold standard. Often patients require more graft material than is generally available from intraoral sites. This has led clinicians to utilize allografts, xenografts, or a combination of autologous and synthetic bone. Extraoral sites can provide a greater volume of autogenous bone than intraoral sites. However, harvesting extraoral donor bone is frequently associated with adverse consequences in excess of the primary objective (ie, the placement of endosseous implants in the posterior maxilla with minimal morbidity). A method for obtaining a significant volume of corticocancellous autogenous bone for augmentation of the maxillary antrum is described. The technique is efficacious and cost effective and results in minimal morbidity.

The conditions for achieving osseointegration of endosseous implants have been well established. The criteria that validate this result concern the physical properties of the implant (eg, material, surface properties), its controlled loading, and its primary stability. Theory regarding primary stability has evolved in recent years. Two clinical cases of totally mobile yet eventually successful sandblasted, large-grit, acid-etched implants serve as illustrations of the possible success of implants deprived of primary stability. In certain circumstances, and if certain recommendations are enforced, it may be possible to consider the preservation, with success, of implants that are completely mobile.

A 40-year-old female patient presented for rehabilitation of an edentulous mandible with endosseous implants. Radiologic examination showed evidence of moderate atrophy in the intraforaminal area and an even more pronounced level of bone resorption in the posterior mandible. The patient desired a fixed rehabilitation with re-establishment of the posterior occlusal plane. From an esthetic standpoint, it was necessary to provide a restoration with crowns the same height as the original teeth while avoiding an unfavorable biomechanical situation. Vertical distraction of the complete mandible was performed using a Martin distractor according to the Hoffmeister technique. At the end of the period of activation and consolidation, the distractor was removed and 8 Frialit-2 Synchro-type implants were placed in predetermined sites and immediately loaded with a cemented transitional prosthesis. Ten months later the definitive restoration was delivered. The absence of any pathologic symptoms or negative radiologic findings 12 months after the surgery suggests a satisfactory result in the short term.