Abstract
In the present investigation, the physical properties of some commercially available composite resins for posterior teeth and visible light-cured resins were examined and compared with one conventional composite resin and one micro-particle filled resin, mainly on the basis of ADA Specification No.27 and ISO Specification No.4049.Soem additional testing procedures were also applied, and the resin/tooth interfaces were observed by EMPA.The following results were obtained:1.The filler contents of two composite resins for posterior teeth(Clearfil Posterior and KG)had almost the same value of one conventional composite resin(Clearfil FII), but one micro-particle filled resin for posterior teeth and three visible light-cured resins fell into the 31 to 63wt% range. 2.Only the water sorption of one visible light-cured resin(Visio Dispers)passed ADA Specification No.27, and the other seven composite resins had values increasing in the following order:KG, Clearfil Posterior, Clearfil FII, Isopast DS, Micro Jar, Heliosit, and Plurafil Super. 3.In the measurement of mechanical properties, eight composite resins passed either ADA Specification No.27 or ISO Specification No.4049. 4.In the measurement of compressive strength, three composite resins for posterior teeth showed values of more than 3, 000kg/cm2 at 24 hours and were 30 to 60% stronger than one conventional composite resin measured at 28 days. 5.In the measurement of diametral tensile and transverse strength, three composite resins for posterior teeth and three visible light-cured resins were as strong as or weaker than one conventional composite resin tested. 6.The values of tensile strength at 6 months were almost the same as those at 28 days, and one composite resin for posterior teeth showed discoloration at this time which did not decrease its tensile strength.The discoloration occurred only at the surface of the specimen. 7.Concerning transverse strength values of three composite resins for posterior teeth, as the thickness of each specimen diminished, the values did not decrease;however, in the case of an extremely thin specimen, the value decreased exceedingly. 8.At the interface between each resin and enamel, none of the eight composite resins showed any gaps, but in the cavity floors of the dentin, almost all of the resin/tooth interfaces had gaps in them.
