Experimental Study Of The Application Of Guided Tissue Regeneration Membrane In The Reconstruction Of The Perio-Implantal Bone Defect

Objective : To comprehend the properties of the PLGA as the carrier of the rhBMP-2 and evaluate the osteogenic capability and the degradation properties of the biomembrane as well as the combined application of the biomembrane with the TCP. Methods: 15 mongrels were recruited in this experiment and the perio-implantal bone defect with the size of 3×5 mm, 3×7 mm, 3×9 mm respectively were prepared in the mandible to build the bony defect model . The rhBMP-2 loaded PLGA microspheres and PLGA membranewere synthesized and combined in terms of the published methods . The defect was implanted with the e-PTFE membrane , PLGA membrane and PLGA membrane combined with rhBMP-2 loaded PLGA microspheres respectively with the corresponding size to the defect in one side of the mandible and the opposite defects were given the same membrane and TCP implantation insuring that the ideal contour of the defect was guaranted .One animal in each group was sacrificed randomly on the 4^th , 8^th , 12^th , 24^th and 48^th week after the operation . The mandible was resected and the operated site was prepared for pathological evaluation of the biological properties of the membranes , the changes of the contour of the bone defect and the reconstruction capability . The osteoinduction and osteoconduction capability and biocompatibility of the membrane was compared among groups. Results : No difference was found between the PLGA membrane group and PLGA membrane combined with rhBMP-2 loaded PLGA microspheres group as the speed of the breakdown of the material and the segmental tissue reaction were concerned .The capability of reconstruction of the defect with the PLGA membrane combined with rhBMP-2 loaded PLGA microspheres was recorded stronger than that of the PLGA membrane while the early stage showed no difference, and the both groups displayed the superior biological properties in the osteogenesis . The comparison in the contour of the defect restoration indicted that the application of the microspheres slowed the metabolism and prolonged the activity of the rhBMP-2 and consequently provided the ideal contour reconstruction results. The reconstruction contour was found related to the size of the lesion .Conclusion: PLGA microsperes is an ideal medium for the BMP and is beneficial to the action of the BMP . PLGA microspere does not lower the degeneration speed of the PLGA membrane remarkably , but improves the osteoinduction and osteoconduc-tion capability of the PLGA membrane and is favorable to the maintainability of the height and thickness after reconstruction .The combined application of the TCP does favor the maintaining of the reconstructed contour.