CELLULAR AND BACTERIAL-COLONIZATION OF BARRIER MEMBRANES UTILIZED FORGUIDED BONE REGENERATION AROUND DENTAL IMPLANTS

During dental implant surgery, it may not always be possible to ensure that all the coronal threads of the implant are within the bone. To o vercome this defect and promote osteogenesis in areas of minimal bone/ implant contact and prevent epithelial downgrowth or soft tissue ingro wth, expanded polytetrafluoroethylene (e-PTFE) membranes may be placed over the implants prior to repositioning the mucoperiosteal flap. The purpose of this study was to examine the surface characteristics of o ne type of e-PTFE membrane using scanning electron microscopy on mater ial retrieved from sites where bone regeneration had been attempted. T he membrane was removed between 4 and 7 months following placement. Af ter fixation, the membranes were examined on both the inner (bony) and outer (soft tissue) aspects. No contamination with microbial organism s was seen except in two of the seven membranes which became exposed o ver the healing period. These showed bacterial colonies on both surfac es. In all specimens, a layer of fibrous connective tissue, attached c ells, and inflammatory cells were observed. The morphology of the atta ched cells was similar on the inner and outer aspects of the membranes . Clinically, it was noted that the e-PTFE membrane was effective in p romoting bone growth over the implant threads where there was no commu nication with the oral environment. However, in those sites where the membrane had been exposed to the oral environment, bone growth had not occurred.