Abstract:
Aim: To assess the effect of different temperature on surface hardness of composite as a function of syringe storage.
Material and methods: A total Number of 70 disc-shaped bulkfill composite resin specimens were used in this study, The specimens were divided into three main groups according to the storage temperature before their use, group 1. (control group) the storage condition was at room temperature 25-28 ℃, group 2 storage condition was at refrigerator 4 ℃ and group 3 storage condition was at freeze -6 ℃. The specimens of the second and third group were subdivided into two sub- groups in which each of the subgroup was cured at two different extraction time which were one immediately curred after extraction from cooling machine and other was after one hour (60 minutes). Vickers hardness values of the top and the bottom surfaces of each specimen were evaluated using Vickers and Knoop hardness testing instrument. The Microhardness were determined through measuring the diameters of indentation which was produced by the pyramidal squarebase diamond indenter. One-way analysis of variance was performed followed by Tukey’s post-hoc test if showed significance. Paired Student t-test was done between paired groups. Three-way ANOVA compared the effect of each factor which was storage temperature group, surface and evaluation time). The results were analyzed using Graph Pad Instat (Graph Pad, Inc.) software for windows. A value of P < 0.05 was considered statistically significant.
