Evaluation of the radiopacity of Bulk-Fill composite resins in primary and permanent teeth

This thesis aimed to compare the radiopacity values of six bulk-fill composite resin materials with different material compositions in relation to the enamel and dentin structures of primary and permanent teeth. The bulk-fill composite resins evaluated in this study were SDR Plus Bulk-Fill Flowable, Estelite Flowable Bulk-Fill, 3M Filtek Bulk-Fill Flowable Restorative, Beautifil Bulk Flowable, X-tra Fill, and Simplishade Bulk-Fill. Each material was prepared in thicknesses of 1, 2, and 4 mm and radiographed together with enamel and dentin samples obtained from primary and permanent teeth using a digital radiographic system. The mean gray values obtained from the radiographic images were measured using Image J software, and radiopacity values were calculated in terms of millimeters of aluminum (mmAl) by applying the aluminum step wedge method. Statistical analyses were performed using IBM SPSS version 23. Normality of data distribution was assessed using the Shapiro–Wilk test. For comparisons involving tooth/material types and thicknesses that did not show normal distribution, Robust ANOVA was applied, and multiple comparisons were conducted using the Holm-corrected robust t-test. The level of statistical significance was set at p < 0.05. The results demonstrated that both the type of material and the application thickness had a statistically significant effect on radiopacity (p < 0.001). In addition, the interaction between tooth/material type and thickness showed a very large effect size (partial eta squared = 0.999). The findings of this study indicate that the radiopacity values of bulk-fill composite resin materials vary depending on the applied thickness, the selected material type, and the interaction between material and thickness. In this regard, when selecting restorative materials for clinical applications, the material's radio-opacity properties, application thickness and relationship with dental tissue should be taken into consideration; it is thought that the findings obtained may be indicative in terms of diagnostic accuracy and restoration follow-up.