Effect of pre-heating composites on film thickness

Abstract

Resin composite has been suggested as a luting material for aesthetic indirect restorations and temperature affects material viscosity. Reports of film thickness from new composites are important. The aim of this study was to analyze the influence of pre-heating two resin composites on its film thickness in order to use it as a luting agent for indirect restorations (inlays and onlays). Three materials were divided into 5 groups. Two resin composites, nanofilled (Z350 XT/3MESPE) and microhybrid (Opallis/FGM), pre–heated and room temperature, and a resin cement (AllCem/FGM) were tested. Following the guidelines from ISO 4049, each material (0,05mL) was pressed under 15kg between two glass plates covered with polyester film for 180 seconds. After pressed, the material was light polymerized with a LED for 40s and the film thickness measured using a digital micrometer. When testing the groups of pre-heated resin composites the material was heated (64°C) on a specific device (CalSet/AdDent) before all procedures. Data were analyzed using t-Student, ANOVA and Tukey post hoc test (?=.05). Resin cement group showed the lower film thickness mean (28,2 µm), followed by the pre-heated microhybrid (45,3 µm). The higher values were obtained with nanofilled composite. Nanofilled room temperature group presented the highest thickness (96,1 µm). Statistical difference was found between all groups. Pre-heating influenced the film thickness of both composites. In this study a microhybrid composite showed better results among resin composite groups. Although not presenting the lower film thickness, as resin cement, some composites could be used for luting indirect restorations when heated.