Properties of 4-META/MMA-TBB resin mixed with Dentin Powder

4-META/MMA-TBB resin is used for apicoectomy and the treatment of vertically fractured roots. Cementum does not form on the resin surface after treatment. Even though cementum is formed, resin cannot integrate it. Application of a compound of resin and dentin powder may improve the binding between resin and cementum. However, dentin powder might adversely affect the polymerization rate, biocompatibility and bond strength of resin. Objectives: The purpose of this in vitro study was to investigate the cytotoxicity and bond strength of a compound of 4-META/MMA-TBB resin and dentin powder. Methods: Bovine roots were pulverized using a mill. Dentin powder was then treated with 10% citric acid and 3% ferric chloride solution (10-3). Five different compounds of resin(Super Bond C&B^®,clear type, Sun Medical, Japan) and dentin powder were prepared by size and volume of powder; 0%, F150µm/12.5%, F150µm/50%, F30µm/12.5%, F30µm/50%. Specimens were made from compound and resin only (6 per group) using plastic molds (F3×1mm). They were polished and stored in antibiotic for 1 day at 37^oC. Cytotoxicity test; MC3T3－E1 cells (density 2×10⁵cells/ml) were seeded and cultured for 1 day. Cytotoxicity was assessed using viability assay kit. Micro-Tensile Bond Strength (MTBS) test; bovine root surfaces were treated with 10-3, and five different compounds were applied on the treated surfaces. After 48 h, the specimens were subjected to MTBS test. Data were analyzed by one-way ANOVA and Scheffe's test. Results: No significant cytotoxicity was found among resin only and the four compounds (P>0.05). Compounds of F30µm/50% and F30µm/ 12.5% exhibited higher MTBS than those of F150µm/50% and F150µm/ 12.5%. Conclusion: The compound of resin and dentin powder had little cytotoxicity, as the same as resin only and the compound with smaller powder size exhibited higher bond strength. Support: JSPS (Grant-in-Aid for Scientific Research, 19592191)