VERTICAL RIDGE AUGMENTATION - WHAT IS THE LIMIT

The aim of this study is to show the possibility of achieving more tha n a 4-mm new vertical bone apposition on partially edentulous ridges. Six healthy partially edentulous patients were treated from July 1993 to September 1993. After accurate radiographic investigation, ail of t he patients were treated using the Branemark System. After insertion, 14 fixtures were left circumferentially exposed for 37 mm. Autogenous bone graft harvested from a bone filter was placed around the exposed threads and completely covered with titanium-reinforced Gore-Tex augme ntation membranes (TR-GTAM). Flaps were coronally displaced to passive ly cover the regenerative materials. Only one of the six membranes was exposed and it was removed immediately. After a 12-month healing peri od the membranes were removed in conjunction with the second-stage sur gical procedure. in the five cases where the membranes were kept cover ed, ail of the available space underneath the TR-GTAM was filled with regenerative tissue. In all of the cases a histologic biopsy was perfo rmed. rn one case ail the space was filled with more than 7 mm of bone . In three cases all the space was filled with more than 5 mm of bone. in one case the most coronal part (approximately 7 mm) of the regener ative tissue was represented by connective tissue: the remaining tissu e was represented by bone. The measurements demonstrated an average of vertical ridge augmentation of 4.95 mm. In the only case where the me mbrane underwent exposure and was then removed there was no regenerati ve tissue present.