Comparison of bioabsorbable and non-resorbable membranes in the treatment of dehiscence-type defects. A histomorphometric study in dogs

Background: The goal of this investigation was to compare, histologically a nd histometrically, the healing process of dehiscence-type defects treated by guided tissue regeneration (GTR) with bioabsorbable polylactic acid (PLA ) membranes and nonresorbable expanded polytetrafluoroethylene (ePTF) membr anes. Methods: Six mongrel dogs were used. Buccal osseous dehiscences were surgic ally created on the distal roots of the mandibular third and fourth premola rs. The defects were exposed to plaque accumulation for 3 months. After thi s period, the defects were randomly assigned to one of the treatments: GTR with bioabsorbable membrane (PLA), GTR with non-resorbable membrane (ePTFE) , open flap debridement (OFD), and non-treated control (NTC). After 3 month s of healing, the dogs were sacrificed and the blocks were processed. The h istometric parameters evaluated included: gingival recession, epithelial le ngth, connective tissue adaptation, new cementum, and new bone area. Results: A superior length of new cementum was observed in the sites treate d by GTR, regardless of the type of barrier used, in comparison with OFD (P <0.05). No statistically significant differences were found between PLA an d ePTFE in any of the parameters with the exception of bone area. PLA prese nted a greater bone area when compared to ePTFE, OFD, and NTC (P <0.05). Conclusions: Within the limits of this study, it can be concluded that both barriers are equally effective for new cementum formation. The bioabsorbab le membrane may provide a greater bone area than the non-resorbable membran e.