comparison of the effect of preheating on the flexural strength of giomer and nanohybrid composite resin

Background. considering the increased use of preheating and novel resin-based materials to restore teeth, the present study investigated the impact of preheating on the flexural strength of a giomer and compared it with a nanohybrid composite resin. methods. two restorative materials (beautifil ii giomer and alpha iii nanohybrid composite resin) were used. thirty rod-shaped samples (adding up to 60 samples) were prepared from the materials above and divided into two subgroups: with and without preheating (n=15). before sample preparation, the giomer and nanohybrid composite resin tubes were preheated at 68°c for 15 minutes in the preheating subgroups. in the subgroups without preheating, the tubes were kept in a room at 25°c. then the flexural strength was compared between the two groups with two-way anova at a significance level of p<0.05. results. the results showed significantly higher flexural strength in the preheated subgroups than in the non-preheated subgroups (p<0.001). in addition, the mean flexural strength values were significantly higher in the giomer groups than in the nanohybrid composite resin groups (p<0.001). conclusion. preheating increased the studied materials’ flexural strengths significantly. the flexural strength of the giomer restorative material was higher than that of the nanohybrid composite resin, irrespective of preheating.