2013 Volume 26 Issue 2 Pages 228-235
Recently, β-tricalcium phosphate (β-TCP) has been used in clinical implant treatment as a bio-absorbable material. We conducted an experimental histological investigation of the absorption process of small β-TCP granules and new bone formed in extraction sockets.The 4 maxillary incisors on both sides of the maxilla were extracted from 4 adult male Crab-eating Macaques. The extraction sockets on the right side were immediately filled with small β-TCP granules (50-150 μm) to form the experimental group, while those on the left side were unfilled, constituting the control group. At 4, 8, 12, and 16 weeks after surgery, the animals were euthanized and histomorphometric observations were performed. After 4 weeks, newly formed bone was observed from the apex to the middle region of the sockets in both groups, while β-TCP granules were also observed in the experimental group. After 8 weeks, the sockets were filled with newly formed bone in both groups, while βTCP granules remained in the experimental group. After 12 weeks, the findings in both groups were similar to those after 8 weeks, while trabecular bone in all sockets was thicker than after 8 weeks. In addition, small β-TCP granules were observed embedded in the trabecular bone in the experimental group. After 16 weeks, trabecular bone in both groups was thicker and denser than after 12 weeks, with a few β-TCP granules remaining in the trabecular bone of the experimental group. Image analysis showed that the amount of new bone formed in the sockets increased in both groups throughout the experimental period. In addition, the ratio of small β-TCP granules to new bone in the sockets of the experimental group decreased over time. Furthermore, after 4 and 8 weeks, the total amount of hard tissue in the experimental group (new bone and remaining β-TCP granules) was larger than in the control group (new bone).Our results revealed that absorption of small β-TCP granules required more than 16 weeks and that the remaining granules enclosed in the new trabecular bone did not inhibit new bone formation. These results indicate that small β-TCP granule materials are useful for extraction socket preservation.
