Development of Osseointegration Method during Sagittal Split Ramus Osteotomy of the Mandible using poly-L-Lactide Screw Mixed with Bone Morphogenetic Protein

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I,Establishment of the method for Poly-L-Lactic Acid (PLLA) Screw Fixation during Sagittal Split Ramus Osteotomy of the Mandible : The physical strength of PLLA-screw is much lower than that of Titanium-screw. Therefore, the method for PLLA screw fixation was established by use of A-O plate screw, custom-made screw-tap and driver. II,Postoperative Changes of the Dento-Facial Deformity Cases Fixed with PLLA Screws : The number of the cases fixed with PLLA screws was 10. Their relapse-tendency was larger than that of the cases fixed with titanium-screws although statistical analysis showed no significant difference. It may be one cause of this tendency that the physical strength of PLLA-screw is lower than that of titanium-one. Therefore, it might be necessary to select the indication of PLLA-screw fixation. III,Development of Bone Morphogenetic Protein (BMP)-PLLA Complex : In this study, the most effective BMP-PLLA complex was made by the mixing in an ultrasonic cleaner in dioxane-solution and freeze-drying. IV,Development of BMP-PLLA Complex Screw and Program of the Future Study : It is very difficult to develop a material which has enough strength for bone fixation and effective dilivery nature for BMP because the harder the material is, the lower the dissolving speed of the factors stored in the material is. Therefore, we have some plans in the program of the future study that bone fixation is done by hard PLLA-materials without BMP and bone steps or gaps is filled by BMP-PLLA complex which has low physical strength.