This study compared clinical, microbiologic, and morphostructural aspects of the healing process in clinical cases treated with expanded polytetrafluoroethylene membranes placed in fresh extraction sockets, which did or did not show early membrane exposure. The examination was focused particularly on morphology of the microbic population and its ability to penetrate membrane pores. Results of the study suggest that use of the membranes is effective in the treatment of fresh extraction sockets with osseointegrated implants; that the membranes are highly biocompatible with gingival tissues; and that early exposure of the membranes during healing hinders the effectiveness of guided tissue regeneration in periimplant tissues.