Flexural strength and surface microhardness of materials used for temporary dental disocclusion submitted to thermal cycling: An in vitro study

Abstract

The objective of this study was to evaluate the effect of temperature variation on surface microhardness and resistance to flexion of different materials used for making a temporary dental disocclusion. One hundred specimens were made of the following materials (n=20): glass ionomer cement (GIC); compomer (CP); composite resin (CR); Blue colour resin composite for temporary dental disocclusion (BTDD); ultraviolet colour resin composite for temporary dental disocclusion (UVTDD). They were stored in distilled water for 24hours and, subsequently, half of the specimens in each group were subjected to thermal cycling (n=10). All samples were subjected to the microhardness test (HMV-2000) and the flexural strength analysis (INSTRON). The data were submitted to parametric statistical analysis (ANOVA) and Tukey's complementary test with a significance level of 5%. In the mechanical tests, all materials except the GIC showed a statistically significant difference between the groups subjected to thermal cycling and not submitted, and thermal cycling (P<0.05) was responsible for the reduction of the values found, except for GIC. In the mechanical tests, all materials except the GIC showed a statistically significant difference between the groups subjected to thermal cycling and not submitted, and thermal cycling (P<0.05) was responsible for the reduction of the values found, except for GIC. For microhardness, the highest average was found for BTDD and UVTDD (P≤0.05). As for the resistance, the flexion was found that in the groups not submitted to thermal cycling there was no statistically significant difference for all materials, except for GIC, for the groups with thermal cycling the materials BTDD and UVTDD showed a statistically significant difference from GIC, however, they did not differ statistically from the CP and CR groups. BTDD and UVTDD presented higher average results of surface microhardness and, in the resistance test, the flexion of these materials behaved similarly to the CP and the CR studied. The temperature variation has an effect on the properties of these materials.