Mechanical properties of low and regular viscosity bulk fill composites in a 3D dentin cavity model

Abstract

This study aimed to evaluate the depth of cure (DC), bond strength (BS), failure mode (FM) and nanoleakage (NL) of restorative systems containing low viscosity bulk fill, regular viscosity bulk fill and conventional composites in a 3 D dentin cavity model. Six restorative systems: [Adhesive: Ambar Universal/Composite resins: Opus Bulk Fill Flow – OBFF, Opus Bulk Fill – OBF and Liss (FGM)] and [Adhesive: Scotchbond Universal/Composite resins: Filtek Bulk Fill Flow – FBF, Filtek Bulk Fill – FB, and Filtek Z250 XT – XT (3 M ESPE)] were used. Conical cavities (n = 13) were prepared in bovine dentin and restored with composite. The DC (%) was analyzed calculating just the bottom-to-top microhardness ratio. The BS (MPa) was determined by push-out testing in the universal testing machine and the FM was analyzed using a stereomicroscope. The NL of silver nitrate was mapped using SEM images of the adhesive interface in additional specimens (n = 3). Data were analyzed using one-way ANOVA/Tukey tests (α = 0.05). There were no statistically significant differences for the DC of the restorative systems. OBFF (11 ± 0.42) presented the highest mean of BS (MPa), while FB (2.61 ± 0.80) showed the lowest mean. Adhesive failures (86%) were predominant. The NL expression was visually similar among the restorative systems. All restorative systems seem to be able to obtain proper cure in 3D dentin cavity model. However, low viscosity bulk fill composites might improve the quality of restorations and provide better clinical longevity.