Abstract
In this study, the physical and mechanical properties of three kinds of posterior composite resins (Bellfirm P, Clearfil Posterior and Micro Jar) were examined for 3 years afterward and compared with one conventional anterior composite resin (Clearfil FII), mainly according to ADA Specification No.27 and ISO 4049. In the examination of water sorption, four composite resins tended to show various increases in water uptake during the 3-year period. One posterior composite resin (microparticle filled resin) was more absorbable and soluble in water than the other posterior and anterior composite resins with conventional fillers. In SEM observations, many air bubbles were found inside the specimens of all four composite resins, because of all mixing type composite resins. The surface layer of all four composite resins showed signs of disintegration, but the center layer of specimens were not disintegrated. As for tensile and transverse strength, all four composite resins reached an equilibrium after 3 days and the values remained steady for 3 months. After about 6 months or 1 year, however, they tended to decrease continuously. In the mechanical properties after 3 years, three posterior composite resins were the same or inferior to the anterior composite resin in tensile strength, but the former was superior to the latter in transverse strength.
