[Experimental study of periodontal tissue regeneration using biodegradable membranes]

This study was designed to investigate the effect on new attachment formation using a biodegradable membrane as a barrier to the regeneration of periodontal tissue. One-wall wide periodontal osseous defects with exposed root surfaces were prepared in three adult mongrel dogs. After surgical debridement of the periodontal defects, 3 types of biodegradable membranes, [Poly(L-lactic acid); (P-L-LA)] membrane, [Poly(lactic acid-co-glycolic acid); (PLGA)] (81: 19 mole%) membrane and PLGA (50: 50 mole%) membrane, were arranged to cover the denuded root surfaces. Specimen blocks were removed 8 weeks postoperatively for histological evaluation of their effect on the regeneration of periodontal tissue. The results were as follows: 1. Gingival regions containing P-L-LA or PLGA (81: 19 mole%) membranes showed delayed wound healing macroscopically. 2. Almost all P-L-LA membranes were present in the experimental sites failing to be resorbed during the 8-week experimental period. PLGA (81: 19 mole%) membranes were also present but showed with some degree of resorption and fragility, while PLGA (50: 50 mole%) membranes were completely resorbed. 3. This showed that the membranes used in this experiment are possible barriers to the generation of new attachment. It is important to make sure keeping the membrane. 4. There was no relationship between osteogenesis and cementogenesis. It seems that osteogenesis was depressed by membrane shrinkage and the gingival pressure which limited "the regenerative space of bone." 5. Moderate resorption was observed on the root surface, and new cementum was formed at the resorbed surface. 6. Ankylosis was observed between the new cementum and bone at the experimental sites. Newly formed cementum was seen on coronal sections of this area.