Light transmission on dental resin composites

Abstract 

Objectives

The purposes of this study was: (1) to examine the light transmittance characteristics of two light-cured resin composites, for different thickness, (2) to correlate the light transmittance through the resin composites and the filler contents, and (3) to determine the penetration depth of the light as a function of the wavelength.

Methods

Two resin composites (Filtek Z250, shade A2 and Filtek Supreme XT, shade A2E) were used. Specimens of six different thicknesses (0.15, 0.25, 0.30, 0.36, 0.47 and 0.75mm) were prepared (n=3). The transmittance at wavelengths from 400 to 800nm was measured using a UV–visible spectrophotometer, before and after light polymerization.

Results and significance

Significant differences were found in the wavelength dependence of transmittance between the two materials, and between the unpolymerized and polymerized stages of each resin composite. At lower wavelengths, the light transmittance of the Filtek Supreme XT resin composite was lower than the Filtek Z250. At the higher wavelengths, however, Filtek Supreme XT presented higher light transmittance. For both resin composites, the penetration depth was higher after polymerization. However, Filtek Supreme XT showed a higher gain in transmittance at the 0.15mm thickness. The difference in light transmittance characteristics of the resin composites may affect their depth of polymerization.

Keywords: Resin composite, Penetration depth, Curing efficiency, Depth of cure and light transmission