Comparison of bioabsorbable and bioinert membranes for guided bone regeneration around non-submerged implants - An experimental study in the mongrel dog

The aim of this clinical investigation was to evaluate the effect of guided bone regeneration around non-submerged implants using different barrier me mbranes. Five adult mongrel dogs were used in this investigation. After hav ing all premolars extracted and implant osteotomies performed in the region s of the former premolars, buccal bone defects were created. Subsequently, 3 implants were placed and the defects treated with 1 of the following 3 mo dalities: a) guided bone regeneration using an expanded porytetrafluoroethy lene membrane, b) guided bone regeneration using a bioabsorbable membrane m ade from a synthetic copolymer of glycolide and lactide and c) no membrane application. Following implant and membrane placement, the mucoperiosteal f laps were repositioned and tightly sutured around the neck of the implants allowing for a non-submerged healing. After a healing period of 6 months, t he animals were sacrificed and the specimens processed for histologic evalu ation. The clinical pretreatment defects between the different treatment gr oups were not statistically different (bioinert membrane group: 4.9 mm; con trol group: 4.8 mm; bioabsorbable membrane group: 4.5 mm). The remaining hi stological defects after 6 months of healing amounted to approximately 2.5 mm in the bioinert membrane group, 5.7 mm in the control group and 6.0 mm i n the bioabsorbable membrane group. A significant difference was observed b etween the bioinert membrane group and the other 2 groups. The mineralized bone-to-implant contact in the bioinert membrane group was 51.5%, in the co ntrol group 46.3% and in the bioabsorbable membrane group 37.5%. The values between the bioinert membrane group and the bioabsorbable membrane group w ere statistically different. The results of this study indicate that bone r egeneration with bioinert e-PTFE membranes around non-submerged implants is possible. The utilized absorbable polyglycolic/polylactid membrane did not show any bone regenerative effect and the results did not differ from the control group without membrane application.