In-vitro characterization and evaluation of mesoporous titanium dioxide composite hydroxyapatite and its effectiveness in occluding dentine tubules

BACKGROUND: To synthesize mesoporous titanium dioxide composite hydroxyapatite (TiO(2)–HAP) and to evaluate its effectiveness in sealing of occluding dentine tubules. METHODS: TiO(2)–HAP was synthesized by chemical precipitation method and characterized using infrared absorption spectrometer, X-ray diffraction, scanning electron microscope, and specific surface area detector. Forty completely extracted molars were prepared and randomly assigned into Control group, Gluma group, HAP group and TiO(2)–HAP group according to different treatments. The characteristics of HAP and TiO(2)–HAP and the sealing effectiveness of dentine tubules in these four groups, including infrared spectrum, surface contact angle, pore size distribution, and re-mineralized enamel surface profiles, were analyzed by suitable characterized techniques. The cytotoxicity of the synthesized TiO(2)–HAP was tested and compared using 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT) colorimetry. RESULTS: Our results showed TiO(2)–HAP group had significantly lower contact angle, higher specific surface area, and wider range of pore size distribution than other groups. The majority of dentinal tubules in the TiO(2)–HAP group were blocked by white matter in a uniformed manner, and the crystals arranged in order grew along the axial direction. In addition, no significant difference in optical density (OD) value was found between control group and TiO(2)–HAP group (P > 0.05), and cell growth was good in TiO(2)–HAP group, indicating no cytotoxicity of TiO(2)–HAP. CONCLUSIONS: The MTT assay identified that TiO(2)–HAP had little effect on the L929 cell line. We showed TiO(2)–HAP might be used as a remineralization agent in enamel caries-like lesions.