Vertical ridge augmentation: surgical protocol and retrospective evaluation of 48 consecutively inserted implants

The aim of this retrospective study was to evaluate the predictability of obtaining a vertical ridge augmentation around dental implants, strictly following a surgical protocol. Fourteen partially and four fully edentulous patients were treated between July 1993 and November 1995. Forty-eight consecutive implants were placed so that the circumference of the upper part of the cover screw was exposed from 2 to 7 mm. In addition to bone chips, autogenous bone grafts harvested with a bone-filtering aspirator were placed around the exposed threads and completely covered with a barrier membrane. Flaps were coronally displaced to cover the regenerative materials. Three of the 22 membranes became exposed prematurely and were removed immediately. The remaining 19 membranes stayed in place for a 12-month healing period until the second-stage surgery. In these 19 cases, where the membrane remained completely covered by the soft tissue, all of the available space underneath the membrane was filled with regenerative tissue. In eight cases a histologic biopsy was performed. Histologic analysis demonstrated vital bone with regularly formed bone cells; in three cases the most coronal part (approximately 1 mm) of the regenerative tissue was connective tissue, and the remaining tissue was bone. This retrospective analysis showed that when the clinical protocol was accurately followed, the possibility of clinical complication was reduced and the results for achieving vertical ridge augmentation around implants were predictable.