Objectives: To evaluate the effect of veneering layer thickness on cuspal deflection of bi-layered fiber-reinforced resin composite restorations.
Materials and methods: Two different resin composite restoration systems Short flowable bulk-fill fiber reinforced resin composite (SFRC) (Ever x flow and Essentia universal) and Flowable bulk fill resin composite (FBF) (SDR Flow+ and Neo Spectra ST) were used in this study. 60 premolars were classified into two groups A and B (n= 30) according to the restorative system used. Each group was classified into three subgroups one, two, and three according to the veneering layer thickness (n=10) (0.5 / 1 / 1.5 mm). The specimens were fixed under ZEISS, Stereo zoom Microscope (50 x) was attached to the camera. Three measurements were taken for each specimen, before restoration/ within 5 and 15 minutes. All collected data were tabulated, and subjected to statistical analysis using SPSS software.
Results: A three-way ANOVA test was used to determine the effect of study variables (composite type, thickness, and time point) and their interaction on the cuspal deflection values (at p < 0.05), which revealed that none of the study variables had a significant effect on the cuspal deflection results (p > 0.05). Additionally, the interactions of all variables were not significant (p < 0.05).
Conclusion: Within the limitations of this study, it is possible to conclude that neither the type of resin composite nor the veneering layer thickness affected the cuspal deflection result.