Biocompatibility of Novel Vacuum Sintered Bodies of Titanium Medical Apatite

Objectives: We have developed novel apatite (Titanium Medical Apatite, TMA) for bone substitute. The objective of this study is to evaluate biocompatibility of novel vacuum sintered bodies with TMA.

Methods: The chemical formula of TMA is Ca₁₀(PO₄)₆·TiO₂·(OH)₂·nH₂O. TMA powders are kneaded with water, and are formed by compacting pressure with vessel. Sintering TMA carried out using resistance furnace with vacuum. 1) In vivo study using rabbit mandible; Ten white Japanese rabbits were operated on to create bone defects in the both left and right side of mandible. These defects were filled with TMA or pure Titanium (Ti, control material), respectively. At 1 and 3 months after the operation, mandibles were removed, and undecalcified sections were stained with hematoxylin-eosin for histological observation. 2) In vitro study using osteoblast; The rat clonal cell line ROS 17/2.8 was cultured in the presence of TMA or Ti. At day 3, 5 and 7, cell proliferation was determined by cell-counting-kit and alkaline phosphatase (ALP) activity was measured colorimetrically. Statistical analysis was done by t-test, and significance was considered when p<0.05.

Results: 1) In vivo study using rabbit mandible; Light microscopic assessment showed that the both TMA and Ti were well tolerated by the surrounding tissue, no adverse tissue reactions being seen in any of sections. At 3 month, the outer surface of both materials was covered by new bone formation. 2) In vitro study using rat osteoblast; The difference between TMA and Ti on the cellular proliferation and ALP activity was not significant in each period (n=5).

Conclusion: Novel TMA vacuum sintered bodies have the same biocompatibility as Ti. It may use as a new bone substitute in implant dentistry.