Filler contents and coefficient of thermal expansion of light-cured resins

Abstract

Light-cured resins have reached remarkable progress in bonding ability to tooth structure, leading to long-term durability of the restoration. From the survey of the reasons for replacement of the restoration, surface roughness and marginal fracture might relate to the clinical problems of the resin restoration. The purpose this study was to evaluate filler contents and thermal expansion of various light-cured resins. Inorganic filler contents were measured by a thermogravimeter and thermal expansion of the light-cured resins were evaluated by a thermomechanical analyzer. Filler contents of universal resins ranged from 42.5 to 68.4 wt% and flowable resins ranged from 42.5 to 68.4 wt%. Thermal expansion of universal resins ranged from 20.8 to 55.1×10^-6°C and flowable resins ranged from 45.3 to 73.2×10^-6/°C. The coefficient of correlation between filler contents and thermalexpansion were-0.690 for universal resins and-0.353for flowable resins. Various size and shape of filler wereobserved under the FE-SEM.