A Study on the Development of Resin Coating Materials Containing TMPT

Abstract

Purpose: The resin coating technique currently is used for indirect restorative procedures after inlay cavity or full cast crown preparation. The technique has been applied to preventing contamination of the target tooth surface, protecting dental pulp tissue and preventing dentinal hypersensitivity in vital teeth. Hybrid Coat (HyC), a one-step resin coating material and bonding agent, has recently become commercially available. In a previous study, the author made the trial resin coating material T33, containing trimethylpropanetrimethacrylate (TMPT) based on HyC, to improve the dentin bond strength. This material achieved a higher shear bond strength than commercial HyC. However, T33 showed no significantly higher dentin bond strength than HyC. To further improve the dentin bond strength, a newly developed trial resin coating material, NC, was produced. Methods: The concentration in NC of camphorquinone (CQ), a kind of photosensitizer, was three times higher than in T33. NC was used as a base coating agent and coat-sponges with different molar ratio of NPG to CQ were used to test the shear bond strength to dentin. Additionally, the degree of polymerization, which is believed to affect dentin bond strength, was investigated to obtain a moderate molar ratio of NPG to CQ. Results: 1. The coating agent having three times more CQ than in T33 was shown to have higher average shear bond strength. However, no significant differences were observed in the shear bond strength in all samples. Shear bond strength did not increase with higher CQ. 2. The dentin shear bond strength of NC using coat-sponges with a different molar ratio of NPG to CQ was shown to be higher in NPG 4.4 and 7.3, which were significantly higher than in HyC. However, this strength was lower in 11.7 and 14.7, which contained a larger molar ratio of NPG. 3. The degree of polymerization of NC using coat-sponges with a different molar ratio of NPG to CQ was shown to be higher in NPG 4.4 and 7.3, but was lower in 11.7 and 14.7. Conclusion: These results showed that the dentin shear bond strength and the degree of polymerization of NC containing three times more CQ than T33 was increased when the molar ratios of NPG to CQ were 4.4 and 7.3, respectively.