The effects of different opacifiers on the translucency of experimental dental composite resins

Abstract

Objective: The aim of this study was to evaluate the effects of different opacifiers on the translucency of experimental dental composite-resins.

Methods: Three metal oxides that are used as opacifiers were tested in this study: titanium oxide (TiO₂), aluminium oxide (Al₂O₃) and zirconium oxide (ZrO₂). Experimental composite-resins were fabricated containing 25wt.% urethane dimethacrylate (UDMA)-based resin matrix and 75% total filler including different concentrations of metal oxides (0, 0.25, 0.5, 0.75 and 1wt.%) blended into silane treated barium-silicate filler. The specimens (15.5mm diameter and 1mm thickness) were light-cured and tested in the transmittance mode using a UV/VIS spectrophotometer at wavelengths from 380 to 700nm under a standard illuminant D65. The color differences (ΔE* ab) between different concentrations of opacifiers were also measured in transmittance mode based on their Lab values.

Results: Statistical analysis by ANOVA and Tukey's test showed a significant decrease (p<0.05) in light transmittance with the addition of opacifiers to the experimental composite-resins. There was a linear correlation between different concentrations of TiO₂ and Al₂O₃ and total transmittance. Total transmittance was also found to be wavelength dependent. The color differences for the concentrations of 0-1wt.% of the opacifiers were above 1 ΔE* unit, with Al₂O₃ showing the smallest color shift.

Significance: The type and the amount of the opacifiers used in this study had a significant effect on the translucency of the experimental UDMA-based dental composite resins. The most effective opacifier was TiO₂, followed by ZrO₂ and Al₂O₃ in decreasing order, respectively.

Keywords: Color; Composite resin; Dental material; Opacifier; Translucency.