The effect of different insertion techniques on the depth of cure and vickers surface micro-hardness of two bulk-fill resin composite materials

Background: The aim of this study was to evaluate the Vickers surface micro-hardness and the depth of cure of two bulk-fill resin composites and one incremental-fill resin composite.Material and Methods: Two Bulk-fill dental resin composites (X-tra Fil, Voco; Sonic-FillTM 2, Kerr Corporation) and an incremental-fill dental resin composite (Filtek™ Z250 XT, 3M ESPE) were used. Sixty cylindrical speci- mens of 4 mm thickness were prepared using split Teflon moulds. Specimens were divided into six groups (n=10) according to the type of the material used and according to the insertion technique applied (bulk or incremental). Prepared specimens were stored dry in complete darkness at 37°C for 24 hours. All specimens were tested for their Vickers surface micro-hardness, on their top and bottom surfaces. The depth of cure of the tested specimens was assessed by calculating the hardness ratio for each specimen. The Vickers surface micro-hardness and depth of cure data were analyzed for normality using Kolmogorov-Smirnov and Shapiro-Wilk tests. Independent sample-t test was used to compare between two groups while One-way ANOVA was used to compare between more than two groups.Results: Significant difference in the Vickers surface micro-hardness and depth of cure values was demonstra- ted among the tested materials (P