Comparative translucency of esthetic composite resin restorative materials

To evaluate the translucency of currently available composites classified by their respective manufacturers as "opaque," "dentin," "body" (or "universal") and "enamel" materials.

Four disk-shaped specimens were produced using a split-ring mould (13 mm in diameter and 2 mm in thickness) from each of 39 proprietary composite restorative materials. Enamel and dentin samples of equivalent thickness were obtained from extracted human teeth. Colour values for lightness (L*), red-green chromatic coordinate (a*) and blue-yellow chromatic coordinate (b*) were recorded against standard white and black backgrounds with a Minolta CR-300 chroma meter under the standard illuminant D65. Translucency parameter values were calculated and compared using analysis of variance and the Tukey test, with significance set at p < 0.05.

A continuum of values for the translucency parameter was obtained, ranging from the most opaque (Filtek Supreme Plus A2D) to the most translucent (Ceram X Duo E2). In general, "opaque" and "dentin" composites yielded relatively low translucency values, "body" (or "universal") composites yielded intermediate values, and "enamel" composites yielded relatively high values. However, the boundaries between these categories were not distinct, and there was some overlap. The mean value of the translucency parameter for human enamel was within the range of values for "enamel" shade composites. The individual values for specimens of human dentin were more variable (i.e., greater standard deviation around the mean) than those for human enamel. The mean value obtained for dentin was intermediate between the ranges for composites with low and intermediate translucency.

The various categories of composite from different manufacturers yielded a wide range of translucency, with minimal distinction between the extremes in adjacent categories. The measured translucency values provided more information than the respective category types. Knowledge of the relative translucency and opacity of different commercial materials can assist clinicians in the choice of composite for clinical use.