Periodontal guided tissue regeneration with a new resorbable polylactic acid membrane
The aim of this article was to evaluate the efficacy of three types of biodegradable, high-molecular-weight DL-lactic-acid membranes, containing 0%, 10%, and 30% low-molecular-weight oligomers, in guided tissue regeneration on the beagle dog Researchers took six beagle dogs and surgically created defects measuring 4.5 mm from the original level and 3 mm wide. The roots were planed to remove cementum, and a notch was placed at the most apical part of the exposed root. The membranes were placed in the experimental site; control sites had similar procedures but no membranes. The animals were sacrificed at two, four, and six months after surgery, and block sections were removed and processed for histologic and histometric analysis. The results showed that without the membrane there was downgrowth of the epithelium to the experimental notch, resulting in a deep pocket. But at six months researchers observed a slight improvement in the periodontal condition and evidence of bone growth. In the control animals there was a dense infiltrate of round cells that was observed in the pocket walls. On the other hand, a number of the experimental teeth showed a complete absence of inflammation. The sites with the PLA 30% at two months showed regeneration of marginal periodontal tissues. Some cases showed a normal junctional epithelium and bone beyond the level of the apical notch. The PLA 30% membrane showed resorption in the most coronal part. The PLA 10% and 0% membrane at four months showed alveolar bone formation from the notch with new cementum formation and new connective tissue. There was no statistical difference among the three membranes in terms of gain in alveolar bone and resorption of membrane, although PLA 30% had already been resorbed by 64% at two months, while PLA 10% reached the same percentage at four months, and 0% at six months. The authors suggest that the speed of resorption seems to be related to the number of oligomers in the membranes. It appears from this study that PLA membranes could be used for GTR in human periodontal lesions. [M.C.R.]
Robert, P.M., and R.M. Frank, J Periodont, 65:414, 1994