Survival of cylindrical implants in composite grafted maxillary sinuses

PURPOSE: This retrospective study investigated the survival of dental implants placed in the maxilla after composite grafting of the sinus and an average of 55 months of loading. PATIENTS AND METHODS: Maxillary sinuses of 88 patients were grafted with autogenous cancellous bone combined with dense hydroxyapatite particles. After an average healing period of 3.4 months, hydroxyapatite-coated titanium endosseous implants were placed. A total of 388 implants were placed in grafted sinus floors, and 82 were placed in onlay grafted nonsinus position in the canine region. The implants were loaded with overdentures and fixed bridges 4 months (mean) after implantation, with a follow-up for a mean of 55 months. RESULTS: The cumulative implant survival was calculated according to the Kaplan-Meier method. Implant survival from the time of loading was 89% in full reconstructed cases and 90% in partially edentulous cases. The overall cumulative implant survival rate, including the loss in the surgical stage, was 82%. CONCLUSION: Implant loss in composite grafted maxillae after 70 months of follow-up was similar to loss in nongrafted maxillae.     

Implant-supported overdenture therapy: a retrospective study

All patients (n = 46) treated with implant-supported overdentures at the Department of Prosthetic Dentistry, Dental and Medical Health Centre, Halmstad, Sweden, from 1986 to 1993 were studied. The clinical examination was completed in 1994. The material was divided into two subgroups: Group A had been initially treatment planned for an implant-supported overdenture, and Group B had been planned for fixed prostheses but because of loss of implants before loading, treatment with a fixed prosthesis was not possible. The authors present their experience and patient reactions to overdenture therapy in two defined groups of patients. The implant failure rate before loading for Group A (n = 12) was 15% (six implants out of 39), and the rate before loading for Group B (n = 29) was 43.6% (68 implants out of 156). After prosthodontic treatment in Group A, the implant success rate after loading was 87.9%, and the overdenture stability was 84.6%. In group B, 17 implants placed in the maxillae were lost after overdenture therapy, which resulted in an implant success rate of 79.3%. A total of eight overdentures, all of which had been placed in the maxillae, were lost, resulting in an overdenture stability of 73.3%. In this study "change of retentive clips" was the predominant prosthodontic complication related to the overdentures, especially in Group B. Most of these complications (62%) occurred in patients with clinical signs of bruxism. Patient reactions to treatment with an overdenture were positive regarding esthetics for both groups. More negative views were recorded in Group B than in Group A in response to function and retention of the overdenture.     

Increase in skeletal muscle protein content by the beta-2 selective adrenergic agonist clenbuterol exacerbates hypoalbuminemia in rats fed a low-protein diet

Between 1990 and 1995, 214 implants were placed in 29 maxillae and mandibles of 22 patients following extraction of all residual teeth as a consequence of severe periodontal disease. All patients were discharged wearing immediate dentures. The implants were analyzed with regard to the number per arch, location, length, and diameter. The 5-year cumulative survival rate was 98.5%. The mean number of implants per arch was 7.5 for the maxilla and 7.2 for the mandible. The preferred implant locations were canines, central incisors, lateral incisors, and second premolars in the maxilla; and lateral incisors, first molars, and canines in the mandible. The mean implant length was 14.7 mm in the mandible and 14.5 mm in the maxilla. The mean implant diameter was 3.8 mm in the maxilla and 3.8 mm in the mandible. The results of the present study indicate that immediate implantation for fixed full-arch reconstruction can be considered a viable treatment alternative in patients with severe periodontal disease.     

Tramadol, a centrally acting opioid: anticonvulsant effect against maximal electroshock seizure in mice

A survey was undertaken to analyze osseointegrated implants placed in irradiated maxillae and mandibles. It was found that nine centers in Japan and two centers in the United States had placed 228 implants in 44 patients. Of 228 implants, 59 were placed in the maxilla, 169 in the mandible. Three of 169 implants placed in irradiated mandibles were removed; 17 of 59 were removed from maxillae. One hundred nineteen implants were placed in the mandible without adjunctive hyperbaric oxygen treatment, of which only 2 were removed. From these results, it is suggested that osseointegrated implants can be placed in the irradiated mandibles of selected patients without hyperbaric oxygen treatment.     

Recombinant coagulation factors

Sometimes, preoperative planning in dental implantology, based on sufficient alveolar height, cannot be verified due to transversal deficiencies. A total of 102 bony mandibles and 95 maxillae were analysed after classification of atrophy, simulating implant insertion at 518 standardised edentulous cross sections with regard to anterior/posterior, mandible/maxilla and class of atrophy. Furthermore, the relation of alveolar height to possible implant length in 86 patients was evaluated retrospectively. Implant length reduction compared with alveolar height was necessary in 10% (mandibles) and 7.5% (maxillae) of the bony-jaw sections and 52.5% (mandibles) and 41.5% (maxillae) of the patients' implant regions. In this respect, the class of atrophy of the bony jaws was more important than the region of simulation. However, the highest differences were observed between mandibles and maxillae, both clinically and experimentally: simulation was possible in all mandibles and 42.5% of the maxillae, but clinical implantation was only possible in 86% of 62 mandibles and 0% of 24 maxillae, mostly due to reduced alveolar height. Alveolar ridge width primarily affected the possible implant lengths. Nevertheless, in four (two mandibular and two maxillary cases) of 58 patients (7%) with sufficient height, a surgical procedure that had already been started had to be stopped. It is expected that cross-sectional radiographical techniques of implantation planning, including ridge-width determination, will gain importance in the future.     

Implant-supported overdentures: the ZAAG attachment system

It has been amply demonstrated during the last decade that there are significant advantages to implant-supported overdentures beyond conventional complete dentures. Several attachment systems exist for connecting the overdenture to the implants, and practically all of them present notable benefits to the patients. This article discusses the use of the Zest Anchor Advanced Generation (ZAAG). This system, an outgrowth from the original Zest attachment, uses both individual implant attachments and bar attachments, and is compatible with all major implant systems. In addition to the retention, stability, and resiliency the ZAAG implant attachment system provides, it has the advantage of placing the resistance force of the attachment close to the implant body.     

Biological factors contributing to failures of osseointegrated oral implants. (I). Success criteria and epidemiology

The aim of this review was to offer a critical evaluation of the literature and to provide the clinician with scientifically-based diagnostic criteria for monitoring the implant condition. The review presents the current opinions on definitions of osseointegration and implant failure. Further, distinctions between failed and failing implants are discussed together with the presently used parameters to assess the implant status. Radiographic examinations together with implant mobility tests seem to be the most reliable parameters in the assessment of the prognosis for osseointegrated implants. On the basis of 73 published articles, the rates of early and late failures of Br?nemark implants, used in various anatomical locations and clinical situations, were analyzed using a metanalytic approach. Biologically related implant failures calculated on a sample of 2,812 implants were relatively rare: 7.7% over a 5-year period (bone graft excluded). The predictability of implant treatment was remarkable, particularly for partially edentulous patients, who showed failure rates about half those of totally edentulous subjects. Our analysis also confirmed (for both early and late failures) the general trend of maxillas, having almost 3 times more implant losses than mandibles, with the exception of the partially edentulous situation which displayed similar failure rates both in upper and lower jaws. Surgical trauma together with anatomical conditions are believed to be the most important etiological factors for early implant losses (3.60% of 16,935 implants). The low prevalence of failures attributable to peri-implantitis found in the literature together with the fact that, in general, partially edentulous patients have less resorbed jaws, speak in favour of jaw volume, bone quality, and overload as the three major determinants for late implant failures in the Br?nemark system. Conversely, the ITI system seemed to be characterized by a higher prevalence of losses due to peri-implantitis. These differences may be attributed to the different implant designs and surface characteristics. On the basis of the published literature, there appears to be a number of scientific issues which are yet not fully understood. Therefore, it is concluded that further clinical follow-up and retrieval studies are required in order to achieve a better understanding of the mechanisms for failure of osseointegrated implants.     

Chromosomal localization of a human mucin gene (MUC8) and cloning of the cDNA corresponding to the carboxy terminus

The objective of this study was to determine the predictability of endosseous implants placed in a maxillary sinus grafted with a mixture of bovine porous bone mineral and demineralized freeze-dried bone. Sixty implants were placed in 20 patients representing 28 sinuses using either a one- or two-stage technique. After an implant loading period of more than 2 years, the survival rate (eg, a clinically functioning implant without signs of mobility or infection) varied from 90% to 96%. No infections or other complications were encountered. The data suggest that this treatment regimen can result in a high rate of survival.     

Linkage of DFNB1 to non-syndromic neurosensory autosomal-recessive deafness in Mediterranean families

A study involving the immediate loading of Br?nemark implants in the edentulous mandibles of 10 patients is reported. The design involved the immediate loading of four widely distributed implants with a transitional fixed implant-supported prosthesis at first-stage surgery, avoiding the need for a removable prosthesis. A sufficient number of additional implants are allowed to heal in the conventional manner to provide sufficient support for a definitive fixed prosthesis even if all of the immediately loaded implants fail. Preliminary results have been favorable, with all patients functioning with a fixed implant prosthesis from the day of first-stage surgery.     

Altered patterns of DNA methylation on chromosomes from leukemia cell lines: identification of 5-methylcytosines by indirect immunodetection

The feasibility of implant treatment in patients after oral ablative tumor surgery has not yet been investigated with consideration of the requisite high periodontal standards. A report on this topic has to deal not only with implant survival but also with implant health, bone response, soft tissue health, failure pattern, time of failure, and ease of restoration. For the assessment of an implant system, an overview must be accomplished that takes into account the different restorations used and their interaction with the implant system that was used. This study presents the Bone-Lock implant system (Howmedica Leibinger GmbH, Freiburg, Germany) in a retrospective investigation after 5 years of follow-up with special emphasis on the prosthetic restorations used following resection of oral malignancies. From early in 1990 through June 1996, we inserted 210 dental endosteal Bone-Lock implants (58 patients) after oral tumor resectioning. Included in the study were 45 patients with 162 implants and prosthetic restorations that had been loaded for 1 year (dentures retained by telescopic or bar-clip or ball attachments, implant-supported prostheses, tooth-to-implant connected bridges). Regular follow-up consisted of evaluation of the Plaque Index (Silness and L?e) and of the Sulcus Bleeding Index (L?e), measurements of pocket probing depth, implant mobility (by means of the Periotest method), bone resorption (according to X-ray findings), and a questionnaire that registered patient satisfaction. The results were evaluated for each restoration and were compared with baseline standards. The overall 5-year survival rate was 83.2%. For implants that had been in place for over 365 days, the survival rate was 93%. The investigation showed that after resection of oral malignancies, patients could be treated with dental implants and superstructures with long-term efficacy similar to that found in healthy subjects considering internationally accepted standards. Implant treatment in tumor patients appeared to offer the most positive periodontic results when use of bar-clip or telescope-retained overdentures was involved. The patient satisfaction level with the described prosthodontic treatment was satisfactory.     

Isolation and characterization of wheat aluminum-regulated genes: possible involvement of aluminum as a pathogenesis response elicitor

This retrospective study involved Japanese patients with prostheses supported by Br?nemark implants following maxillectomy. Questionnaires were sent to 75 institutions, and data on 19 patients were collected from 8 institutions. The mean age of patients at the time of implant placement was 64.2 years (range 22 to 82 years). The mean follow-up time was 27.6 months. Of the 81 implants placed, 16 were lost for an implant survival rate of 80.2%. The effects on implant survival rate of radiotherapy, chemotherapy, hyperbaric oxygen therapy, and the support system of the prosthesis were analyzed, but no significant differences were observed.     

Clinical assessment of olfactory dysfunction in Parkinson''s disease

The possibility of placing endosseous implants in the edentulous maxilla is frequently reduced by inadequate bone volume of the residual ridge. In totally edentulous maxillae with knife-edge conformation, insufficient thickness is frequently associated with insufficient height of the residual ridge in the posterior maxilla because of pneumatization of the maxillary sinuses. This surgical method combines grafting of the maxillary sinuses, onlay grafts on the buccal side of maxillary posterior segments, and sagittal osteotomy of the anterior maxilla with interpositional bone grafts. Five to six months after maxillary reconstruction, Br?nemark implants were placed and, after osseointegration occurred, implant-supported dental prostheses were fabricated. Three patients have been treated with this method and 22 implants have been placed. The mean follow-up after final prosthetic rehabilitation has been 16 months; survival rate has been 100%. Despite the small number of patients and the short follow-up, preliminary results have shown very promising results.     

Ten-year results for Br?nemark implants immediately loaded with fixed prostheses at implant placement

This investigation was initiated to develop a method to provide patients with a fixed provisional prosthesis placed at the time of implant placement. Sixty-three standard 3.75-mm Nobel Biocare implants of varying lengths were placed into mandibular sites in 10 patients and followed for up to 10 years. Twenty-eight implants were immediately loaded at implant placement, providing support for fixed provisional prostheses, while 35 adjacent implants were allowed to heal submerged and stress-free. Following a 3-month healing period, the submerged implants were exposed and definitive reconstruction was accomplished. All 10 prostheses supported by 28 implants placed into immediate function at the time of implant placement were successful during the 3-month healing period. Of these 28 implants placed into immediate function, 4 ultimately failed. Of the 35 submerged implants, all are osseointegrated and in function to date. Life-table analysis demonstrates an overall 10-year survival rate of 93.4% for all implants. The 10-year life-table analysis of survival is 84.7% for immediately loaded implants and 100% for submerged implants. Statistical analysis of the submerged versus immediately loaded implants demonstrates failure rates for immediately loaded implants to be significantly higher (P = .022 by the log rank test). These data demonstrate that although mandibular implants can be successfully placed into immediate function in the short term to support fixed provisional prostheses, long-term prognosis is guarded for those implants placed into immediate function distal to the incisor region.     

Identification and characterization of a new splicing variant of vascular endothelial growth factor: VEGF183

The purpose of this study was to determine implant survival rates by means of life table analyses for a cohort of patients not part of a prospective efficacy trial and treated by practitioners at varying experience levels. Prognostic variables associated with implant failure were identified by means of proportional hazards models and advanced statistical methods that account for patient effects. Ninety-nine consecutive patients treated from 1987 to 1991 with follow-up to 1994 were included in this retrospective study. A total of 384 dental implants (79.7% Br?nemark, 19.3% IMZ plasma-sprayed, 1% IMZ hydroxyapatite-coated) were placed and subsequently supported 108 prostheses. Survival and proportional hazards modeling were used to generate Kaplan-Meier survival curves and to identify variables associated with implant failure. Survey data analysis was used to adjust for any patient effects for variables identified as significant through the proportional hazards models. Thirty-four implants failed over the follow-up period (median follow-up time 3.6 years), resulting in an overall failure rate of 8.9%. Seventeen of 99 patients experienced an implant failure. When prosthesis type was excluded from the modeling process, survey data analysis identified posterior location and an implant width of less than 4.0 mm as being associated with implant failure (all P < .05).     

The use of transitional implants for immediate fixed temporary prostheses in cases of implant restorations

While the original Br?nemark implant protocol has continued to evolve, the avoidance of implant loading during osseointegration remains a prerequisite with all implant systems. Immediately loaded transitional implants have recently been developed to support the fabrication of a fixed provisional prosthesis that provides implant patients with improved aesthetics and function during the osseointegration period. In this manner, osseointegration can occur free from prosthetic and transmucosal loads. This article describes the use of transitional implants and presents a classification of three different case types.     

Long-term follow-up on hydroxylapatite-coated cylindrical dental implants: a comparison between developmental and recent periods

PURPOSE: To compare success rates for dental implants placed from 1985 through 1988 and from 1989 through 1991, and to investigate the factors associated with success or failure. PATIENTS AND METHODS: All hydroxylapatite-coated cylindrical implants placed from 1985 through 1991 were followed yearly. Lifetable survival analyses compared implant success for a "developmental period" from 1985 through 1988 (4 to 8 years follow-up) and a "recent period" from 1989 through 1991 (1 to 4 years follow-up). Reasons for success or failure, time from implant placement to removal related to failure reason, outcome after implant removal, and a morbidity analysis are included. RESULTS: The 7 to 8-year cumulative success rate for all implants placed in the developmental period (maxilla and mandible combined) was 86.5%; it was 84.2% for all maxillary implants and 87.5% for all mandibular implants. The cumulative success rate for all implants placed in the recent period was 97.5%; it was 97.5% for all maxillary implants and 97.6% for all mandibular implants. The difference between the two periods was statistically significant only for the anterior maxilla. Regression analysis on the interval success rates indicates that interval failure did not follow a linear relationship with time. The most common reasons associated with failure were lack of keratinized gingiva, poor oral hygiene, mechanical overload, and malposition. CONCLUSION: Comparison with previously reported cumulative success rates indicated learning curve experiences comparable with other implant systems. Improvements in hardware, surgical and prosthetic techniques, and patient selection have led to an improvement in success rates with the recent period implants.     

Magnetic resonance imaging lesion analysis in neurofibromatosis type 1

The purpose of this prospective study was to investigate the clinical outcome and marginal bone resorption of three different endosseous implants placed in the anterior mandibles of 15 elderly patients. Eleven women and 4 men (ranging from 65 to 80 years, mean 71 years) had three different endosseous implants placed in the anterior mandible; one titanium plasma-sprayed cylinder implant (4-mm diameter), one titanium cylinder implant with hydroxyapatite coating (4-mm diameter), and one standard threaded titanium implant (3.75-mm diameter). Three months later, at the second-stage surgical procedure, ball abutments were connected and an overdenture was placed. At 12, 24, and 36 months, marginal bone resorption and Periotest values were recorded. None of the implants was lost in this period. An analysis of variance with repeated measurement was performed annually to test the existence of significant differences between the implants. When differences appeared, paired t tests were used to identify which differences were significant. Bonferroni multipliers were used to adjust for multiple testing. When marginal bone resorption was concerned, threaded titanium and hydroxyapatite-coated implants had significantly better scores than titanium plasma-sprayed cylinder implants. Periotest values for hydroxyapatite-coated implants were significantly better than test values for the other implants after 2 years. After 3 years significance was obtained between hydroxyapatite and screw-shaped implants only (P < .05). It was concluded that titanium plasma-sprayed cylinder implants have a less favorable prognosis than the other implants used in this study.     

Rehabilitation of patients with severely resorbed maxillae by means of implants with or without bone grafts. A 1-year follow-up study

Forty-three patients with severely resorbed maxillae who had been referred for implant treatment were assigned to one of three treatment groups: bone grafting and implant placement (graft group); modified implant placement but no bone grafting (trial group); or optimized complete dentures (no-implant group). Sixteen, 20, and 7 patients, respectively, were assigned to the three groups. At the 1-year follow-up, 10% of the implants had been lost. Only a few of the failures (3/22) occurred after prosthesis placement. The cumulative success rates were 83% in the graft group and 96% in the trial group. A substantial reduction of the grafted bone, especially of the onlay grafts, occurred in many patients. During the period from prosthesis connection to the 1-year follow-up, marginal peri-implant bone loss was on average 0.5 mm. Despite the often demanding procedures involved, all but one patient in each implant group said that they would undergo the treatment again. Most patients were very satisfied with the treatment outcome and their improved masticatory ability. Those who had renounced implant treatment appeared modestly adapted to their optimized dentures, but reported retention problems and less satisfaction with mastication.     

Comparison of position repeatability of a human operator and an industrial manipulating robot

STATEMENT OF PROBLEM: Implant-supported restorations in the partially edentulous jaw have been performed at the Mayo Clinic for more than 10 years. Clinical performance of the implants and the prostheses should be reported to ensure effectiveness of this procedure. PURPOSE: This retrospective study described results for implant survival, implant fracture rate, prosthetic complications, and design changes that may impact these results. MATERIAL AND METHODS: A retrospective chart review was conducted of all registered implant patients in a large multispecialty medical center. Patients with a partially edentulous jaw who had received endosseous implants to support and retain dental prostheses were included in this review. Implant survival and fracture, prosthetic complications, and demographic data were recorded and analyzed through Kaplan-Meier methods. RESULTS: A total of 1170 implants were placed in four anatomic locations: anterior maxilla, posterior maxilla, anterior mandible, or posterior mandible. Location of implants was shown to have no effect on implant survival (p = 0.7398), implant fracture rates (p = 0.2385), screw loosening (p = 0.8253), or screw fracture (p = 0.2737). Development of new restorative components has resulted in significantly better rates of implant survival without fracture (p = 0.0054), screw function without loosening (p < 0.0001) and screw function without fracture (p = 0.0013). Implant survival seems to have been improved with the new components (p = 0.0513). CONCLUSIONS: Implant survival in this study was independent of anatomic location of implants. Virtually all clinical performance factors were improved by design changes in implant restorative components that were brought to market in early 1991.     

Implant reconstruction of the jaws and craniofacial skeleton

Full oral rehabilitation with a high degree of success is now possible with osseointegrated implants. Osseointegration is a direct connection between living bone and the titanium implant at the level of the light microscope. Osseointegrated implants are currently used to replace single teeth, support fixed bridges and stabilize full dentures. These implants can also be placed extraorally for attachment of facial prosthesis. The surgical technique used to place implants intraorally into jaws or facial skeleton is performed in two stages using a local anesthetic and/or conscious sedation. During stage I surgery, holes are placed into the jaw using a series of gradually larger diameter burs until the desired diameter and depth of the bony preparation is achieved. The implant is then placed. The implant must remain undisturbed for 4 months for osseointegration to take place. Stage II surgery is then required to remove the mucosa over the implant and place the transmucosal abutment. After 1-2 weeks of healing, the restorative dentist can take an impression and fabricate the prosthesis. On occasion, it is necessary to augment the height and width of the atrophic jaw with autogenous or allogeneic bone grafts prior to implant placement. Bone grafts are sometimes placed on the floor of the nose or the floor of the maxillary sinus. Guided tissue regeneration is a technique used to generate bone within bony defects adjacent to implants. With long-term rates of success (5 years) of 99% for implants placed in the mandible and 95% for those placed in the maxilla, reconstruction of the jaws and cranial facial skeleton with osseointegrated implants has become the treatment of choice.