Evaluation of New Bone Formation and Osseointegration Around Subperiosteal Titanium Implants with Histometry and Nanoindentation.

PURPOSE: To assess the quality and quantity of newly formed bone around rough-surfaced titanium subperiosteal implants stabilized with two different fixation techniques and to investigate nanoindentation as a method for measuring the elastic properties of the bone around these implants. MATERIALS AND METHODS: Ten 6-month-old white rabbits were used in this study. One femur received a subperiosteal implant fixed to the bone with screws. The other femur received a subperiosteal implant stabilized with a trough (bed) in the bone area, plus fixation screws. After a 3-month healing period, the animals were sacrificed and each titanium plate was resected along with the surrounding bone. Histometric measurements of osseointegration were performed on 16 titanium plates, and 16 titanium plates were evaluated qualitatively (hardness and modulus of elasticity) with nanoindentation. A regression model was used to analyze the data. RESULTS: Subperiosteal implants placed into a trough performed significantly better than those placed on top of the cortical bone in terms of percentage of bone in direct contact with the titanium plate, length of new bone, and percentage of area of new bone. The mechanical properties (modulus of elasticity, hardness) of the newly formed bone above the plate measured at the microstructural level were significantly inferior to those of the mature cortical bone below the plate. CONCLUSION: Subperiosteal implants placed into a trough performed better than those placed on top of the cortical bone, but it seems that 3 months of healing is not enough to achieve optimal integration and bone maturation around them. Nanoindentation can offer valuable insight into the elastic properties of the microstructural component of the bone.

The Custom Endosteal Implant: histology and case report of a retrieved maxillary custom osseous-integrated implant nine years in service.

The Custom Endosteal Implant (CEI) is a custom-cast osseo-integrated implant that has evolved to replace the "old" fibro-integrated subperiosteal variant. This newly developed implant achieves osseous integration by utilizing a hydroxyapatite (HA) coating, and a specialized grafting technique that produces much improved success rates relative to its fibro-integrated subperiosteal predecessor. This case reported here represents a maxillary CEI implant that was placed and in functional service for 9 years before being retrieved and processed for histologic examination subsequent to the patient's demise. In addition, due to infection that occurred shortly after placement, an early provisional procedure with fluoridated HA was also performed. Histologic analysis of the postmortem specimen revealed a fully integrated new bone formation intimately surrounding the previously dehisced implant strut. The latter had previously been decontaminated and grafted with a thin layer of fluorapatite (FA) material. Results including histologic analysis confirmed complete osseo-integration of the implant following successful FA graft revision.

Severe mandibular atrophy treated with a subperiosteal implant and simultaneous graft with rhBMP-2 and mineralized allograft: a case report.

A 71-year-old patient was successfully rehabilitated by means of a 3D model-derived, hydroxyapatite-coated titanium subperiosteal mandibular implant. The implant was specifically designed to allow bone augmentation. The deficient bone was simultaneously grafted with mineralized bone allograft and recombinant bone morphogenetic protein -2 (rhBMP-2). The 32-month postoperative cone beam computerized tomography follow-up showed vertical bone augmentation beneath the implant frame.

The use of laser technology (Er;Cr:YSGG) and stereolithography to aid in the placement of a subperiosteal implant: case study.

The use of laser technology has helped this clinician to provide treatment with less postoperative pain and increased healing. The subperiosteal implant is a modality that has been used for several decades, although its popularity has declined in favor of endosseous dental implants. In some instances, however, it remains the treatment of choice, specifically in the atrophic mandible (where placement of endosseous implants is not possible) or when placement would increase the chances of jaw fracture. This article reports the case of a patient rehabilitated using a simplified surgical protocol involving laser surgery and stereolithography.

A descriptive 18-year retrospective review of subperiosteal implants for patients with severely atrophied edentulous mandibles.

STATEMENT OF PROBLEM: Fabricating dentures for the patient with severe mandibular atrophy can be a challenge for both the dentist and patient. Subperiosteal implants with a mandibular overdenture may be a solution for the atrophic mandible. PURPOSE: The purpose of this retrospective study was to review the survival of mandibular subperiosteal implants placed at the University of Missouri Kansas City (UMKC) School of Dentistry Graduate Prosthodontics program between 1982 and 2000. MATERIAL AND METHODS: Forty subperiosteal implants were placed in atrophic mandibles of 40 patients (33 women, 7 men) between 1982 and 2000. The age range of the patients was 47 to 80 years of age at time of placement (mean=62 years). Each patient was reviewed clinically by an author (DJM). Manual depression and lifting of the framework were used to evaluate the stability of the implant. Additionally, the implants were observed for any movement. Each patient was questioned for pain or discomfort. Each patient was examined for observable inflammation and intraoral exposure of the framework and questioned as to whether the implant had satisfied the patient and met the patient's expectations. RESULTS: Thirty-nine of the 40 original patients were recalled in 2000. One patient had died. Fourteen patients had implants for over 10 years, 12 patients had implants between 5 and 10 years, and 12 patients had implants for less than 5 years (mean time of implant service=8 years). Thirty-eight patients had the implant in place with no sign of inflammation or mobility, 1 patient with diabetes had inflammation around one of the struts. All patients were wearing their prostheses, and there was no sign of exposed implant framework for any patient. All patients reported a high level of satisfaction with the implant. CONCLUSIONS: Within the limitations of this study, the mandibular implants placed at UMKC were still functioning, and all patients denied any discomfort or pain from the prostheses. Patients reported they were comfortable and able to function with the implant-supported prosthesis.

Ramus hinges for excessive movements of the condyles: a new dimension in mandibular tripodal subperiosteal implants.

Some subperiosteal mandibular implants of the earlier designs failed because of bone resorption beneath the posterior portions of the implant. Conversely, bone loss was observed rarely in the anterior region. The resorption was more profound posteriorly because there can be as much as 250 lb. of biting force per square inch and the bone is more porous than in the symphyseal region, which receives about 25 lb. per square inch. The independent movements of the condyles and the inferior border of the mandible at the gonial angles have dictated the success or failure of conventional mandibular subperiosteal implants in many of the earlier designs. Often, the rigidity of the implant framework prevents its posterior portion from moving in unison with the flexion and flexibility of the condyles upon the opening and closing of the mouth. Flexure usually is 2-4 mm in range and varies according to the quality of bone, age, sex, and musculature of the patient. Approximately 2% of these patients demonstrate movements of up to 4 mm. This has influenced an altered approach to posterior design-especially with tripodal mandibular subperiosteal implants. A brief history of the contributions of the earlier pioneers and their important contributions to the subperiosteal implant follows: G. Dahl inserted the first mandibular subperiosteal implant and was awarded his patent in 1941. Gershkoff and Goldberg, were the first to report clinical cases with mandibular subperiosteal implants in the United States. N. Berman reported on a direct bone impression of the mandible and transosseous wiring of the implant to the bone for stabilization. I. Lew introduced his own surgical bone impression technique for the mandibular subperiosteal implant and had published case histories on maxillary and mandibular implants. B. D. Weinberg reported an early unilateral subperiosteal implant consisting of a latticework portion that seated over the bone connected to the protruding post by four uprights. Leonard I. Linkow reported on the posterior unilateral mandibular subperiosteal implant. He followed up with a 5-year report, an 8-year follow-up report, and a 12-year report. R. L. Bodine reported his experiences with mandibular subperiosteal implants. A. N. Cranin and P. Schnitman introduced the Brookdale bar for an improved support of an overdenture for the mandibular subperiosteal implants. L. I. Linkow made some significant changes in the mandibular subperiosteal implant. D. D'Alise reported on the O-ring design for retention of implant dentures. R. A. James reported on the support system and perigingival mechanism surrounding oral implants and changed the subperiosteal based on peri-implant tissue behavior. L. I. Linkow reported on an entirely new mandibular tripodal design concept as well as a distinct change in the surgical protocol for obtaining the bone impressions without exposing those parts of the body of the mandible from the mental nerves to the ascending rami.

Application of stereolithography to subperiosteal implant manufacture.

Subperiosteal implants are an accepted and proven technique with a good long-term outcome. Although a technique of computed tomography to computer-assisted machining became available to drop the number of surgeries to one for ascertainment of bone topography, the problem of accurate bone modeling remains an issue. The advent of stereolithography as a new tool for modeling anatomy for subperiosteal implants and the advances in computed tomography offer a higher degree of build accuracy and repeatability than available before.

Subperiosteal implants provide another option for dentistry: one practitioner's experience.

Many options are available to patients to maintain occlusal function. Dental implants provide yet another. This paper examines the author's experience with one type of dental implant technique. The findings are based on data contained within the data base the author maintains of approximately 3,000 individual implants. The maxilla is the more challenging of the two arches, and the subperiosteal allows us to choose between grafting procedures and endosseous implants or a combination of subperiosteal implant and root form implants. Each has its positives and negatives. The At Risk statistical computer analysis of the author's database validates the use of the subperiosteal as an alternative.

Forty years of experience with subperiosteal implant dentures in 41 edentulous patients.

Forty-one complete mandibular subperiosteal implant-supported and retained dentures were consecutively inserted between 1952 and 1971, and patients were monitored through 1992. After variables and methods of follow-up were described, the implants were divided into three categories: 14 (34%) nonfunctional implants, 9 (22%) functioning implants, and 18 (44%) functional implants prematurely terminated by death or cause unrelated to implant condition. Five percent of the implants failed by 5 years, 22% failed by 10 years, 34% failed by 20 years, and none failed after 20 years. Nine implants were still functioning 21 to 36 years after insertion, of which five were functioning for more than 30 years. The implants that were developed later were notably superior to earlier implants. The results of this review could be interpreted to suggest consideration of mandibular subperiosteal implants for selected patients, particularly those with resorbed mandibles.

Use of subperiosteal implants with distal filling ports in the correction of the atrophic alveolar ridge.

A subperiosteal tissue expander with a filling port attached to the distal end of the prosthesis has been successfully used on 10 patients during the past 2 years. The design has resulted in eliminating the dehiscence problem encountered when the midline incision was used to insert the original expander and its centrally placed filling port. The ability to use a bilateral incision or expander insertion has minimized the incidence of inferior alveolar nerve damage in the severely atrophic mandible.

An overview of implant hardware.

This paper overviews dental implants emphasizing design concepts, material composition, and prosthetic abutments. Within the space limitations, all systems can not be shown in total and we do not infer superiority or inferiority with the inclusion or exclusion of any design, concept, or abutment.