Poly-D-L-lactic acid membranes for bone regeneration

Purpose: To histologically and histomorphometrically evaluate the biocompatibility and the biological properties of perforated and nonperforated poly-D-L-lactic acid (PDLLA) resorbable membranes, using a model of calvarial monocortical bone defects in domestic pigs. Methods: A total of 6 10 x 10 x10 mm circular calvarial bone defects were prepared in each of the 3 adult female large white domestic pigs and assigned to the following experimental groups: negative control, nonperforated membrane only, perforated membrane only, bone only, bone + nonperforated membrane, and bone + perforated membrane. The PDLLA membranes were fixed by PDLLA pins by means of an ultrasonic device. After 40 days, bone blocks containing the defects were harvested and histologically processed. Results: A close contact between the PDLLA devices and the surrounding bone was found, and no trace of inflammatory tissue or signs of infection were detected. Bone regeneration occurred from the preexisting bone with a centripetal pattern. Incomplete bone filling was found in empty defects, whereas all sites filled with bone showed a complete bone formation, irrespectively of the presence and the type of membrane used. Conclusion: PDLLA membranes and pins showed to be highly biocompatible toward bone tissue and to do not interfere with the bone healing process of monocortical calvaria defects in domestic pigs. No adjunctive effect of PDLLA membranes, irrespectively of their perforated/nonperforated structure, could be evidenced in terms of bone regeneration under the present experimental conditions. Further studies are needed to investigate the regenerative potential of such devices in other clinically relevant models.