HISTOLOGICAL MORPHOLOGY OF THE E-PTFE TISSUE INTERFACE IN HUMANS SUBJECTED TO GUIDED BONE REGENERATION IN CONJUNCTION WITH ORAL IMPLANT TREATMENT/

The purpose of the present investigation was to study the histological morphology of the e-PTFE membrane/tissue interface in 5 humans subjec ted to GBR treatment in conjunction with oral implant treatment. Oral implants (Branemark System(R)) were inserted in extraction sockets 1 t o 2 months after extraction of periodontally diseased teeth, The impla nts were placed approximately 2 mm below the surrounding bone margins, Specially designed 3 mm high cover-screws with horizontal slits for t issue ingrowth were applied to the implants and covered with e-PTFE me mbranes (GoreTex Augmentation Material). Re-entry was made 7 months la ter, except in 1 case where the membrane was removed 1 month postopera tively due to exposure and infection. In the remaining 4 sites, circul ar biopsies comprising membranes, tissues and cover-screws were retrie ved. The specimens were fixated, processed and sectioned for light- an d transmission electron microscopy. The space between the membrane and the cover-screw was occupied by fibrous tissue and varying amounts of bone, A cell- and vessel-rich fibrous tissue separated the bone from the membrane in the majority of the specimens. The membrane itself was penetrated by fibrous tissue. Fibroblasts and macrophages were the ma in cell types found in the fibrous tissue. The presence of irregularly shaped cells and unevenly distributed collagen fibres, indicated that the absence of bone formation may be due either to micromovements in the e-PTFE/tissue interface or to formation of fibrous tissue undernea th the membrane by penetrating fibroblasts or a combination of these 2 phenomena.