Effect of Preheating on the Mechanical Properties of Resin Composites

Abstract

ObjectivesThe purpose of this study was to compare the flexural strength and modulus of two commercial resin composites, at room temperature and 40, 45 and 50°C prior to light polymerization with standard and step-cure protocols.MethodsOne nanohybrid (Grandio, VOCO, Cuxhaven, Germany), and microhybrid composite resin (Filtek Z250, 3M ESPE, St. Paul, MN, USA) were used. The materials were inserted into rectangular moulds at room temperature or preheated to a temperature of 40, 45 or 50°C and cured with standard or step-cure protocols with high intensity halogen (Elipar Highlight, 3M-ESPE, St. Paul, MN, USA). Ten specimens were prepared for each preheating and light curing protocol. A three-point bending test was performed using a universal testing machine at a crosshead speed of 1 mm/min. The data were analyzed by one-way analysis of variance and Tukey’s post hoc tests (P<.05) to examine the effect of curing protocol and preheating. Pearson’s correlation test was used to determine the correlation between tested mechanical properties and preheating.ResultsThere were no statistically significant difference between tested mechanical properties of the materials, curing protocols and temperature of the materials. No significant correlation was found between preheating and tested mechanical properties.ConclusionsThe mechanical properties of the tested materials did not changed by preheating so the tested materials could be preheated because of the other potential clinical advantages like more adaptation to the cavity walls.

Effect of Preheating on Microleakage and Microhardness of Composite Resin (An in Vitro Study)

“…This could result in improved mechanical properties. Whether preheating could improve the mechanical and physical properties or not of microhybrid universal composites Z250 3MEspe and nanohybrid composite resins Grandio Voco; it is a question needed to be verified (25)(26)(27).…”

“…The high viscosity of heavily filled materials, as packable composites and microhybrid composites, may create a difficulty in producing a good marginal adaptation which may lead to void formation especially at the critical gingival margin (26). Therefore, microhybrid composite was selected for this study as it was suggested that preheating increased its flow properties, and hence improved its handling characteristics as reported by knight et al (28), in 2006.…”

Effect of pre-heating composite resin on gap formation at three different temperatures

“…[9] Daronch et al . found no significant differences in the intrapulpal temperature between room temperature and preheated resin composite at similar restorative stages.…”

Effect of Precuring Warming on Mechanical Properties of Restorative Composites

“…One of these studies investigated the effect of pre-warming on flexural strength and found significance in some but not all tested composites [11]. In contrast Fróes-Salgado et al and Uctasli et al reported no significant difference in flexural strength between preheated and room temperature composite [14, 21]. Further investigation is warranted in this respect.…”

“…On the other hand, two other studies found no significant difference in flexural strength between heated and nonheated composites [14, 21]. It is worth mentioning that those three studies evaluated different composite brands and this may explain different findings as different brands may behave differently due to differences in monomer composition and fillers type and size.…”