International Journal of Periodontics & Restorative Dentistry, 04/1992

Placement of implant fixtures in an ideal position for restoration is not often possible using standard protocol, because most patients lack sufficient bone in the alveolar process. To facilitate ideal restorative placement of implant fixtures, principles of guided tissue regeneration can be used to provide adequate bone and prevent dehiscence and fenestration of the implant. Four cases of such treatment are presented.

The potential for guided tissue regeneration was evaluated in one-walled interproximal sites in Macaca fascicularis. Histologic differences were evaluated at 1 and 3 months. Within the experimental (barrier) group, 100% of the root surfaces with potential for regeneration were covered with new cementum, whereas the control specimens had 20% or less new cementum. The amount of regeneration was determined by the position of the barrier membrane; the more coronal the barrier, the greater the regeneration. Observations indicated that the optimal time for barrier removal is between 1 and 3 months.

With the use of a positional index, the restorative dentist and laboratory technician can be provided with an accurate record of implant fixture location after first-stage surgery. Thus it is possible to fabricate a master cast with implant analogs and initiate laboratory procedures immediately after first-stage surgery, and a provisional restoration can be processed and delivered at the time of second-stage surgery. A case report is presented to illustrate the technique.

Fifteen patients, men and women aged 18 to 65 years, were treated for periodontitis. Each patient had at least two bilateral intrabony defects; one was designated the experimental site and the other the control site. Both sites were surgically debrided, but one osseous defect received an HTR polymer implant. Patients were followed for 12 months postoperatively. Maximum pocket reduction occurred within 2 months of initial therapy in both experimental and control sites. Initially, pocket reduction was significantly greater in implanted sites than in control sites, but this difference did not occur subsequently. At the end of the 12 months, pocket reduction responses were similar at control and implanted sites.

Case reports describe the use of a radiographic depth gauge in conjunction with computerized axial tomography. This gauge identifies for the surgeon the precise site of implant preparation that will not only be in accord with anatomic vital structures, but also achieve parallelism with adjacent teeth and other implant sites. Discrepancies in angulation can be corrected, and maximum suitable fixture length can be determined.

This clinical investigation evaluated the effect on subgingival surfaces of three instruments: hand instruments and ultrasonic instruments with modified and unmodified inserts. Ten operators (five dentists and five dental hygienists) performed randomly assigned operative procedures. Pocket depth, instrument limit, and instrument efficiency were evaluated for each type of instrument. The results indicated that there are advantages to using modified ultrasonic inserts for scaling and root planing.

Ten metal-ceramic restorations with buccal porcelain butt margins and palatal metal beveled margins were fabricated for periodontally hopeless teeth. After cementation, the experimental crowns remained in the oral environment for 3 to 6 months; the teeth were then extracted and used for microscopic and microleakage evaluation. All ten crowns showed at least a small amount of microleakage, but adaptation of beveled margins proved to be superior to that of shoulder porcelain margins.