International Journal of Periodontics & Restorative Dentistry, 06/1994

Primary splinting of fixtures with bar attachments has proven to be clinically effective for overdentures on osseointegrated implants in the edentulous mandible. However, in vitro investigations indicate that a more favorable force transfer to the individual fixtures can be attained by secondary splinting of four implants with tapered telescope crowns, compared to primary splinting with rigid or jointed bar attachments. Moreover, in contrast to jointed attachments, the telescope crowns ensure a stable denture position. These results underscore the need to clinically test telescope crowns as anchors for overdentures on osseointegrated implants. Telescope crowns on four implants allow an optimal restorative concept of overdentures with the bridgelike design of the removable suprastructure.

The purpose of this study was to evaluate: (1) the surgical protocol, effectiveness, and reliability for vertical ridge augmentation using a new titanium-reinforced membrane and osseointegrated implants; and (2) the histologic characteristics of the interface between a pure titanium implant and newly regenerated human bone. Five patients received 15 conical Brånemark-type implants in six different surgical sites requiring vertical augmentation. The implants protruded 4 to 7 mm from the bone crest. Pure titanium miniscrews (1.3 x 10 mm) were positioned distally to the implants, protruding 3 to 4 mm from the bone level. The implants and the miniscrews were covered with a titanium-reinforced membrane, and the flaps were sutured. Membranes were removed at the stage 2 surgery after 9 months of healing. Measurements of biopsy specimens showed a gain in bone height from 3 to 4 mm. Histologic examination showed that all retrieved miniscrews were in direct contact with bone. Histomorphometric analysis of bone contact gave a mean value of 42.5 ± 3.6% for five of the six examined miniscrews. The results suggest that the placement of implants protruding 3 to 4 mm from the top of resorbed bone surfaces may result in vertical bone regeneration to the top of the implant cylinder and that the regenerated bone is able to osseointegrate pure titanium implants.

The sinus cavity and the rarefied posterior maxillary bone make it difficult to place implants posterior to the first premolar. Placement of an implant into the pterygoid plate area has been used to overcome these anatomic obstacles, allowing successful restoration of the area. Sixty-four implants were placed in 49 patients. Forty-three implants are in function. There have been 7 failures. The technique is described and a typical case is illustrated.

A technique to increase the quantity of gingival tissue around a tooth scheduled for extraction is described. When the tooth is reduced subgingivally, the body will spontaneously produce sufficient amounts of tissue to completely cover the condemned root, thereby simplifying the implant-or socket-retention procedure.

Use of hemisection in an attempt to preserve multirooted teeth that have furcation involvement has increased in recent years. However, there are few long-term studies of the success of this treatment. Furthermore, it is difficult to compare results of different studies because of differences in the length of follow-up and the criteria for failure. Results of various studies were reduced to a common denominator to allow comparison. The compiled results of studies on hemisection revealed an average reported failure rate of 13.1%. This rate was compared with results of studies on implants; the failure rates of the two treatment alternatives are not substantially different. Thus, because hemisection is a relatively simple, inexpensive treatment with a good chance of success (given appropriate case selection), it should always be considered as an option before molar extraction.

Maxillary sinus grafting with demineralized freeze-dried human cortical bone and resorbable tricalcium phosphate is discussed in three different situations: when minimal bone remains coronal to the sinus (crestal approach); when between 1 and 4 mm of bone remains coronal to the sinus (lateral approach); and when greater than 4 mm of bone remains coronal to the sinus (lateral approach with simultaneous implant placement). Cases that demonstrate all three situations are presented.

Guided tissue regeneration was successfully used to treat a patient who had a mucogingival defect associated with interdental bone loss. The defect involved the mandibular left central incisor, which exhibited 6.0 to 7.0 mm of attachment loss on the facial, mesial, and distal aspects. A regenerative procedure consisting of critic acid demineralization and placement of a demineralized freeze-dried bone allograft and Gore-Tex membrane was performed. At 8 months, a gain of 4.5 to 5.0 mm, or 64% to 83%, in clinical attachment levels was demonstrated. Root coverage was 86%.