[Guided bone regeneration around dental implants using a bioabsorbable membrane. A pilot investigation in experimental animals]. / Geführte Knochenregeneration um dentale Implantate mit einer bioresorbierbaren Membran. Eine tierexperimentelle Pilot-Untersuchung.

The aim of this experimental investigation was to evaluate the effect of guided bone regeneration around immediately placed implants using different barrier membranes. Five adult fox hounds were used in this investigation. After extraction of all premolars in the lower jaw, implant osteotomies in the regions of the former premolars and additional buccal bone defects (5 mm x 5 mm) were created. Subsequently, the implants were placed. The defects were treated with one of the following three modalities: (a) guided bone regeneration, using a bioinert expanded polytetrafluoroethylene membrane, (b) no membrane application and (c) guided bone regeneration, using a bioabsorbable membrane made from a synthetic copolymer of lactide and glycolide. After a healing period of six months, the animals were sacrificed and the implants with the surrounding tissues processed for histologic evaluation. The clinical pretreatment defects between the different treatment groups were not statistically different (bioinert membrane group: 4.8 mm; control group: 4.3 mm; bioabsorbable membrane group: 4.9 mm). The remaining histological defects after a healing period of 6 months amounted to 3.2 mm for the nonresorbable group, to 5.6 mm for the control and to 6.3 mm for the bioabsorbable group. A significant difference was observed between the bioinert membrane group and the other two groups. The mineralized bone-to-implant contact in the bioinert membrane group was 52%, in the control group 47% and in the bioabsorbable membrane group 43.3%. The values were not statistically significant different. The results of this study indicate that a partial bone regeneration with bioinert e-PTFE membranes around immediately placed implants is possible. The utilized bioabsorbable polylactide/polyglycolide membrane did not show any bone regenerative effect, and the results did not differ from the control group without membrane application.

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 membranes. Five adult mongrel dogs were used in this investigation. After having all premolars extracted and implant osteotomies performed in the regions of the former premolars, buccal bone defects were created. Subsequently, 3 implants were placed and the defects treated with 1 of the following 3 modalities: a) guided bone regeneration using an expanded polytetrafluoroethylene membrane, b) guided bone regeneration using a bioabsorbable membrane made from a synthetic copolymer of glycolide and lactide and c) no membrane application. Following implant and membrane placement, the mucoperiosteal flaps were repositioned and tightly sutured around the neck of the implants allowing for a non-submerged healing. After a healing period of 6 months, the animals were sacrificed and the specimens processed for histologic evaluation. The clinical pre-treatment defects between the different treatment groups were not statistically different (bioinert membrane group: 4.9 mm; control group: 4.8 mm; bioabsorbable membrane group: 4.5 mm). The remaining histological 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 in the bioabsorbable membrane group. A significant difference was observed between 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 control group 46.3% and in the bioabsorbable membrane group 37.5%. The values between the bioinert membrane group and the bioabsorbable membrane group were statistically different. The results of this study indicate that bone regeneration 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.