The International Journal of Oral & Maxillofacial Implants, 05/1994

This comparative dental implant investigation evaluated the hypothesis that differences may exist in the interfacial nature of the oral tissues related to various implant materials and designs. The study investigated undecalcified bone and support tissues apposing titanium and ceramic one-stage and two-stage root-form and blade-type endosteal dental implants placed into the mandibles of adult mongrel dogs. Animals were euthanized at periodic internals and the tissue prepared for computerized morphometric and associated morphologic protocols. This study demonstrated dynamic support tissue at the implant interface involving both mineralized and unmineralized tissues. Longitudinal analyses after 1 year of prosthetic loading suggest that titanium implant systems, both blade and root-form, appear to be apposed by more bone than ceramic systems. Subjectively, the bone appears denser after longer periods of load, perhaps because of more complete lamellar compaction of the bone supporting the implants. Keywords: alumina oxide ceramic, bone, dental implants, fibrous connective tissue, interface, morphometry, scanning electron microscopy, titanium

This clinical functional state report involved 20 patients, edentulous at least in one jaw. Ten patients were provided with implant-supported fixed prostheses and 10 patients with implant-retained overdentures. After an average observation period of 8.4 months, the patients' individual degree of satisfaction with the treatment was determined through the use of a questionnaire. In addition, a clinical examination was performed, the dysfunction index (Helkimo) was determined, and border movements and chewing patterns were recorded by using an optoelectronic jaw tracking system (Jaws 3D). The data were compared with a control group having natural dentition. The subjective assessment showed that none of the patients had any complaints. Both test groups showed higher Helkimo index values than the control group. The evaluation of the movement patterns of the overdenture group showed significantly different values than the control group regarding the chewing cycle duration, velocity of chewing, and maximal mouth opening capabilities. No significant differences were noted between the prosthesis group and the control group. Keywords: edentulism, functional state, implant retained overdentures, implant-supported fixed prostheses

In patients with extensive bone resorption, implant placement posterior to the mental foramen is a problematic surgical procedure. In 100 patients with edentulism in the posterior part of the mandible, 250 Nobelpharma implants were placed after transposition of the inferior alveolar nerve. Implant survival, marginal bone loss, and neurosensory function were recorded 1 week and 6 months after implant placement. In 91 of the patients, additional examinations were performed at 12 months postoperatively, and 72 of these were followed until 18 months after implant placement. Implant survival rate was 95.2% at 6 months, 94.2% at 12 months, and 93.6% at 18 months postoperatively. During the 12-month period following abutment connection, mean marginal bone loss was 0.3 mm (range 0.1 to 5.1 mm). One week after implant placement, normal neurosensory function was recorded in 21% of the patients, 32% had diminished function, and 47% had no function. Six months postoperatively, 77% had normal function, 21% diminished function, and 2% had no function. At 18 months postoperatively, 94% had normal sensation, 4% had diminished sensation, and 1% had no sensation. Some complications occurred and these are discussed. Indications and contraindications for the procedure are suggested. Keywords: complications, implant, inferior alveolar nerve, nerve transpositioning, surgery

The effects of implant placement into a pretapped preparation versus non-pretapped preparation on the osseointegration of bone-anchored dental implants were evaluated. Experimentally available implants made of commercially pure titanium were implanted into rabbit mandibles and tibial metaphyses. In the self-tapping group, bone was not tapped prior to implant placement; while in another group, the bone was tapped prior to implant placement. Following implant placement, healing continued for 1, 3, and 6 months, at which time the torque levels required for implant removal were measured. In the mandible there was no statistically significant difference between removal torque for the self-tapping group and that of the tapping group. In the tibia, removal torque for the self-tapping group was statistically significantly lower than that of the tapping group at 3 and 6 months postoperatively. Keywords: dental implant, osseointegration, removal torque, self-tapping, tapping

The purpose of this study was to determine whether differences in implant survival, health of the peri-implant tissues, and/or the level of oral hygiene could be observed among five implant systems and, further, two suprastructure modalities in mandibular implant-overdenture treatment. The implant systems included were Bonefit ITI (n = 71 patients), IMZ (n = 150 patients), Brånemark (n = 47 patients), Screw-Vent (n = 35 patients), and Bosker TMI (n = 27 patients), with a mean observation period of 21.2 months (SD 8.8) after implantation. The implants were either nonconnected (n = 72 patients) or connected (n = 255 patients). For statistical reasons, one implant for each patient was randomly selected and processed for data analysis. The health of the peri-implant tissues was assessed on a four-point scale at four sites for each implant and the oral hygiene was assessed dichotomously, by two independent observers. The interobserver agreement was considered acceptable with Cohen's kappa 0.62 and 0.68 respectively. With regard to implant survival and oral hygiene, no major differences could be observed, both among implant systems and between the suprastructure types. The health of the peri-implant tissues surrounding Bonefit ITI implants appeared somewhat healthier when compared to the other implants, especially at mesial sites (P = .02). No statistically significant differences in health of peri-implant tissues for any of the sites could be demonstrated between implants that were and implants that were not connected. It was concluded that for the three outcome measures implant survival, health of the peri-implant tissues, and oral hygiene, differences between implant systems and differences among suprastructure types in mandibular overdenture treatment were small and probably not clinically relevant. Keywords: clinical study, dental implants, overdentures, suprastructures

The aim of the present study was to analyze the results of local augmentations of alveolar ridge defects using bone grafting and implants (n = 55) in 16 partially edentulous patients. The mean period of functional loading was 27 months (range 2 to 80). Two implants were lost during initial healing because of wound dehiscence over the graft with subsequent infection and loosening of the implants. Two implants were left unexposed during abutment connection, so that 51 out of 55 implants placed were in function at the time of follow-up. Peri-implant parameters, such as plaque accumulation, gingival inflammation, pocket depth, and implant mobility, compared well to the results found previously with implants without bone grafts in partially edentulous jaws. Plaque accumulation was registered for 18.9% of all tested abutment surfaces, while signs of gingival inflammation were present in only 3.6%. All implants were immobile, exhibiting Periotest values between - 5 and 5. A significant change in marginal bone height around the implants (0.3 mm) was found during the period of functional loading. Keywords: bone grafts, implants, ridge augmentation

Between April 1988 and April 1992, 190 immediate implantations (93 primary immediate implantations and 97 secondary immediate implantations performed at 6 to 8 weeks postextraction) were performed at the Department of Oral Surgery of the Dental School of the University of Vienna, Austria. After an average follow-up of 12.4 months, peri-implant pocket depth, the gingival index, the hygienic index, and the degree of bone resorption were examined. A life-table approach (Kaplan-Meier) was applied for statistical analysis, and showed no difference between primary and secondary immediate implants. Also, none of the parameters examined demonstrated a statistically significant difference between the two groups. However, compared with the groups of secondary immediate implants, the group of primary immediate implants showed a tendency towards deeper pocket formation and an increased frequency of membrane dehiscences that may be due to the poorer quality of the soft tissue covering. Keywords: GBR technique, guided bone regeneration, immediate implantation

This report is based upon 6 years of experience with craniofacial implants used for the retention of maxillofacial prostheses. A total of 30 patients were treated with 92 implants. Of these implants, 86 were uncovered, 8 were subsequently buried because of persistent soft tissue problems, and 15 failed to achieve or maintain osseointegration. The overall success rate was 73.3% and varied according to implant location and radiation status. The temporal bone was the most reliable site (92.5%), followed by the nasal floor (72.2%), and lastly the orbit (65.0%). Most notably, the success rate for the irradiated orbital group was a low 58.3%. Keywords: craniofacial implants, osseointegration

To evaluate the possibility of regenerating bone around endosseous dental implants, 3t implants were placed into postextraction sockets or other bony defects, and human demineralized freeze-dried cortical bone powder (DFDB) mixed with tetracycline was packed around the exposed parts. Implants were covered with expanded polytetrafluoroethylene (e-PTFE) membranes for 4 to 6 months until abutment connection, unless the membranes were prematurely exposed and had to be removed. Bone biopsies from nonsupporting regenerated bone were taken from some of the patients and examined histologically. Whenever complete coverage was maintained throughout the healing period (4 to 6 months), complete bone regeneration resulted. Early membrane removal mainly resulted in partial bone regeneration. Histologically, regenerated bone consisted of particles of devitalized bone in contact with newly formed woven or lamellar bone with some connective tissue around them. Osteogenic activity was even present 1 year post-grafting. Thus, DFDB is capable of promoting bone formation around dental implants if complete flap coverage and the membrane presence can be maintained throughout the healing phase. Keywords: allograft, augmentation, demineralized, freeze-dried bone, implants

Treatment involving the prosthetic rehabilitation of a patient with an acquired maxillary defect is reported. Definitive prosthesis support was provided by bilaterally placed hydroxyapatite-coated endosseous implants in the zygomatic buttress. Keywords: implants, maxillectomy, obturator