Tooth extraction sockets effectively recovered after application of rhbmp-2 combined with porous particles of hydroxyapatite

摘要

Concave defects in bone after tooth extraction often cause various difficulties in prosthetic dentistry, which require an effective method of local bone recovery. We have devised porous particles of hydroxyapatite (PPHAP) for bone augmentation. Recombinant human BMP2 was combined with PPHAP and implanted into the sockets after extraction of premolars in rabbit mandibles. Control groups with PPHAP alone, and without any implant were designed. Quantitative histological analysis of bone formation was done in the divided areas within the socket, the orifice, middle, and, bottom areas in the apical direction, and also in the central and lateral wall areas in the horizontal direction. Four weeks after operation, in the non-implant and the PPHAP-alone groups, active bone formation was limited to the bottom and lateral wall areas. Little bone formation was observed in the central and orifice areas. On the other hand, in the BMP2/PPHAP group new bone formation was seen as early as in 2 weeks in almost all areas of the socket. After 4 weeks, total amounts of new bone in the BMP2/PPHAP group were about two times higher than in the control. The bone formation was particularly rich in the orifice areas, resulting in the flat or convex-shaped recovery of alveolar bone after tooth extraction. This application of the rhBMP2/PPHAP composite material will provide a useful tool in clinical dentistry.