Guided bone regeneration around endosseous implants using a resorbable membrane vs a PTFE membrane

The aim of the present experimental pilot study was to assess bone regenera tion underneath resorbable barrier membranes vs non-resorbable extended pol ytetrafluoroethylene (ePTFE) membranes in peri-implant defects. Two implant s were inserted into surgically created defects on each side of the mandibl es of 6 adult beagle dogs 3 months after extraction of all premolar teeth. One implant on each side was covered with a porous polylactic acid membrane or a ePTFE membrane, respectively, while the second implant served as cont rol. Fluorochrome labelling was administered during the Ist, 5th, 12th and the 18th week. Three animals each were evaluated after 3 and 6 months. Bone regeneration was assessed by measuring the distance from the first fluoroc hrome label to the level of the regenerated bone immediately adjacent to th e implant surface and to the top of the newly formed alveolar contour both on the lingual and buccal side. The increase in bone height was significant ly higher compared to the controls under both barrier membranes after 3 mon ths at the top of the alveolar crest but not immediately adjacent to the im plant surface. After 6 months, bone height was significantly increased only at the top of the alveolar contour underneath the ePTFE membranes, while b one underneath the polylactic acid membranes showed signs of superficial re sorption. It is concluded that guided bone regeneration underneath barrier membranes can restore alveolar bone contour but is not necessarily associat ed with a higher bone/implant contact. The use of resorbable membranes may be associated with untoward biological effects at later stages, when membra ne degradation starts due to degradation products of the polymer material o r decreasing membrane stability. Future efforts have to refine the relation between degradation kinetics, membrane porosity and mechanical properties of degradable barrier membranes to improve membrane performance.