An in vitro comparative evaluation of the depth of cure and flexural strength of four tooth colored direct core build-up materials

Abstract

The purpose of this study was to comparatively evaluate the depth of cure and flexural strength of 4 tooth colored direct core build-up materials- a nanocomposite, microhybrid composite, resin modified GIC and a modified composite. Materials and Methods: 240 samples of 4 tooth colored core build-up materials were prepared from polytetrafluoroethylene molds to assess the depth of cure and flexural strength. Samples were divided equally into 4 groups (n=60) [Group I- nanocomposite, Group II-micro hybrid composite, Group III- resin modified GIC and Group IV-modified composite-Cention N]. Each group was further divided into 2 subgroups. Subgroup A (n=40) for measuring depth of cure by Vickers’ hardness number and Subgroup B (n=20)- for measuring flexural strength. Subgroup A of each group was further divided equally into 4 divisions according to thickness of the restorative material placed into the designated mold (1mm, 2mm, 3mm and 4mm). The results were statistically analyzed using ANOVA, multiple comparisons (post-hoc test) were carried out using Bonferroni test.Results: At different heights of the specimen, Group IV recorded the highest mean micro hardness followed by Group II, Group I and Group III. Higher mean micro hardness was recorded by all the core build-up materials in the radiated surface compared to non-radiated surface. Higher mean flexural strength was recorded in Group IV followed by Group II, Group I and Group III respectively.