The International Journal of Oral & Maxillofacial Implants, 02/1993

The success of osseointegration depends in part on the state of the host bed. Concerns have therefore been raised about osteoporosis, a condition believed to be associated with a decrease in bone quality and quantity. However, the orthopedic literature indicates that osteoporotic fractures heal readily and that the level of bone mass and estimates of the parameters associated with bone remodeling present considerable overlap between patients with osteoporosis and control subjects. It also appears that osteoporosis, as diagnosed at one particular site of the skeleton, is not necessarily seen at another distant site. Although the prevalence of osteoporosis increases among the elderly and after menopause, the results of this study indicate that implant failure rate is not correlated with age and sex. A review of the literature and of results of a series of patients treated does not provide a compelling theoretical or practical basis to expect osteoporosis to be a risk factor for osseointegrated dental implants. Keywords: dental implant, osseointegration, osteoporosis

Placement of implants in the posterior mandible is limited by the height of bone between the alveolar crest and the inferior alveolar canal. This paper discusses a surgical technique to reposition and protect the neurovascular bundle so that endosseous implants may be placed. A rectangular window is cut in the cortical bone posterior to the mental foramen. The mental foramen is not violated and the mental nerve is not relieved peripherally into the soft tissue. Cancellous bone is removed from the window and the canal is uncovered. A vessel loop placed around the bundle repositions and protects the nerve laterally. After implant placement, the bundle is replaced within the cortical window and the mucoperiosteal flap is sutured. Avoiding manipulation of the terminal branches of the inferior alveolar nerve reduces the risk of permanent nerve damage. Keywords: implants, inferior alveolar nerve, surgery

One to nine Nobelpharma osseointegrated implants were placed in the posterior maxillae of 213 consecutive partially edentulous patients. Reconstruction was completed with a ceramic fixed partial denture with follow-up of 5 to 70 months (mean 30.3 months) after loading. Thirty-four implants in 29 patients failed; eight were replaced and one of these failed. Thus, the overall failure rate was 4.8% (35/732). The failure rate in type IV bone was only slightly higher than that in types II and III bone (5.5% versus 4.6%). The failure rate in the entire molar area was 5.3% compared with 4.5% in the premolar area (P = NS), and the failure rate of 7-mm implants was 9.5% compared with 3.8% for implants of all other lengths (P = .01). Keywords: bone quality, bone quantity, implant length, osseointegrated implants, posterior maxillae, treatment planning

Brånemark dental implants with ball attachments supporting overdentures were used as alternative treatment to combined lingual-vestibuloplasty with free split-thickness skin graft and removable dentures in 25 consecutive patients with mandibular alveolar ridge atrophy. Ninety-three fixtures were placed. Ball attachments were mounted on the fixtures, and implant-supported overdentures were inserted 3 to 4 months after fixture placement. The observation period after implant activation and prosthesis insertion varied from 12 to 27 months with a median observation period of 18 months. The overall success rate of individual implants was 97% (90/93). The prosthesis function rate was 100% (25/25). The 1-year success rate of individual implants was 98% (91/93) with a prosthesis function rate of 100% (25/25). No persistent surgical or prosthodontic complications were observed. Preliminary results indicate that osseointegrated Brånemark dental implants with ball attachments supporting overdentures can be a successful alternative to combined lingua-vestibuloplasty with free split-thickness skin graft and removal dentures in patients with denture problems related to mandibular alveolar ridge atrophy. Keywords: atrophy, mandible, oral implants, preprosthetic surgery

One of a series of patients with extremely resorbed maxillae treated with bone grafts from the hip in combination with Brånemark self-tapping fixtures died in a car accident 4 months after implant surgery. Autopsy specimens from this patient were analyzed to evaluate the amount and extent of osseointegration after 4 months of healing. Histologic examination revealed that minimal bone was in direct contact with the titanium and the general pattern was that of soft tissue screw anchorage. There were no signs of sequestering of the transplanted bone. The connection between the nasal cavity and the sinus mucosa with respect to the transplants seemed to be without adverse reactions. The superior part of the transplant did show signs of newly formed bone. The grafted specimens showed indications of delayed bone response compared to the nongrafted situation. All implants were clinically stable as studied postmortem. Keywords: bone transplant, implants, osseointegration

The responses of 100 patients to load on Tübingen ceramic implants and natural teeth were analyzed to learn about the facets of qualitative mechanoperception. This approach revealed four factors of mechanoperception: dullness, intensity, localization, and persistence. Dullness, localization, and persistence were discriminated between teeth and implants. Intensity perception, however, depended on load only. Keywords: endosseous implants, qualitative mechanoperception

The prognosis of natural and implant abutments depends in part on the complementary and/or antagonistic biomechanic and calcium homeostatic functions of the adjacent alveolar bone. Whereas bone morphology is determined by peak strains, strain rates, and strain distributions, infrequent error strains on abutments have a greater impact on the adjacent alveolar bone than those generated during ormal activity. Alveolar responses depend on the immediate prevailing systemic and local demands, although unexpected abutment failures will continue until such influences have been investigated further. Keywords: alveolar bone support, implant and natural abutments

A retrospective analysis compared the success rate of osseointegration of Nobelpharma implants at stage 2 surgery. The implants had been placed using either a mucobuccal fold incision or a crestal incision. A total of 386 implants was placed in 92 patients; 265 implants were placed in 60 patients using a mucobuccal fold incision, with a success rate of 98.8%, and 121 implants were placed in 32 patients using a crestal incision, with a success rate of 98.3%. Implants can be placed using either a mucobuccal fold incision or a crestal incision to achieve predictable success. Keywords: crestal incision, implant surgery, incision design, mucobuccal fold incision, osseointegration, titanium implants

The aim of preventive implant therapy is to prevent or delay loss of alveolar ridge bone mass. For use in an anatomic study of 60 mandibles, resorption of the alveolar ridge was classified into four preventive stages: (1) after extraction of teeth; (2) after initial resorption; (3) when the ridge has atrophied to a knife-edge shape; and (4) when only basal bone remains. Implantation in stage 3 necessitates removal of the knife-edge ridge to create space for cylindrical implants. Therefore, implantation in stage 2 is advocated to prevent the development of stage 3. The aim of implantation in stage 4 is to prevent total loss of function of the atrophic mandible. Keywords: classification, implants, mandible, prevention

A survey was undertaken to determine the number of centers in Canada with an active involvement in extraoral osseointegration. It was found that six centers had placed 222 implants in 91 patients in Canada. The individual implant success rates for the Canadian experience were compared with the published Swedish and United States' experience. The Canadian experience is combined with the Swedish and United States' experience to provide retrospective multinational multicenter data. The data given should be viewed as providing trends only and not as definitive expectations of predictable success rates. The success rates are considered likely to change with time as the number of patients treated increases and the duration of follow-up is extended. The mastoid region in nonradiated patients is considered to provide a high degree of predictable individual implant success. The success rates in radiated patients yield far lower success rates, which vary with anatomic location. The criteria for success in using craniofacial implants need to be defined and should reflect the differences between extraoral and intraoral implants. Keywords: craniofacial implants, criteria for success, extraoral implants, multicenter study, multinational study, radiation therapy

A method of implant-retained overdenture treatment based on the early use of the final denture base during registration of the maxillomandibular jaw relation is described. Using this stable denture base, an accurate recording of jaw relation and an adequate try-in procedure are facilitated without displacement of the base, especially in the situation of an unfavorable flat edentulous mandibular residual ridge. Keywords: implants, overdenture, prosthodontics

The traditional treatment for an edentulous maxilla opposed by a partially edentulous mandible with a complete denture and a distal extension removable partial denture is fundamentally inadequate. Continuing resorption of alveolar bone under the denture base of the removable partial denture causes changes in the occlusal plane. Consequently, overloading of the anterior maxillary region occurs, usually leading to increased bone resorption in the anterior maxillary ridge. Placement of implants beneath the distal extension denture base of the removable partial denture can result in a stable and durable occlusion. Two patients in whom the use of implants combined with a cast metal removable partial denture provided occlusal stability and improved functional comfort are presented. Keywords: implants, removable partial denture, shortened dental arch