Synthesis of nano-fluorapatite and their biocompatibility test as restorative dental materials

Fluorapatite (FA) ceramics are one of the most restorative materials used in dentistry due to their mechanical properties. FA preserves potential properties such as acid resistance in the saliva environment and biocompatibility with human hard tissue. These properties are potentially developed for several dental applications, especially dental cement for repairing damaged dental enamel, either solely FA cement or in corporation with glass-ionomer cement. This study synthesized nano-fluorapatite (nano-FA) via an ultrasonic assisted-precipitation method using chicken eggshells as a calcium source. The result showed a single phase of fluorapatite with sponges-like particles on the nanometer scale. To be used as restorative dental materials, the obtained nano-FA cement was tested in vitro, including toxicity and degradability. Toxicity test was carried out through MTT assay using dental pulp fibroblast with various doses (12.5 μl, 25 μl, 50 μl, 0.4 mg, 0.8 mg, 1.6 mg) and various methods (direct and elution). The MTT assay showed no cytotoxicity effect of nano-FA cement shown by the high viability cell (> 90%) for all doses and methods. In addition, optical microscope imaging showed the interaction of nano-FA cement with fibroblast cells in the direct method confirming the bioactivity of nano-FA cement to induce cell adhesion and proliferation. This optical image was supported by statistical analysis that informed the significance of the direct method resulting in higher average cell viability than the elution one. Nevertheless, ANOVA analysis showed that doses had no significance on cell viability following MTT assay results. Moreover, the biodegradability test in the culture medium for 7 days showed a higher degradability rate of nano-FA cement (0.77 mg/hour) compared to commercial product GIC FUJI (0.13 mg/hour). These results suggest that nano-FA cement may be useful for dental pulp capping applications.