Fate of bioresorbable poly(lactic acid) microbeads implanted in artificial bone defects for cortical bone augmentation in dog mandible.

The fate was examined of poly(lactic acid) microbeads implanted in large artificial defects created in cortical bone of dog mandibles. Two poly(lactic acid) polymers--poly(L-lactic acid) (PLA 100) and poly(DL-lactic acid) (PLA 50)--were used to make microbeads by solvent evaporation with poly(vinyl alcohol) as surfactant. Histological observation of non-decalcified mandibular bone showed that no real bone regeneration existed in the experimental bone defects 18 months after PLA 100 microbeads implantation. The same observation was made 6 months after implantation of PLA 50 microbeads. PLA 100 and PLA 50 microbeads appeared unable to induce regeneration of cortical bone defects of dog mandible, in contrast to previous observations in man for PLA 50 large implants. The failure is tentatively assigned to the presence of poly(vinyl alcohol) at the surface of microbeads.