Measurement of translucency of tooth enamel and dentin

Objective. To determine the translucency of human and bovine enamel and dentin using reflection spectrophotometers. Material and Methods. The color of intact human and bovine enamel and dentin specimens was measured over a white and a black plasticine backing using two spectrophotometers with different aperture sizes; translucency parameter (TP) and contrast ratio (CR) were calculated. Plasticine was used as backing because the specimens were not uniform. The TP values of five composite resins measured over the backings of plasticine and reflectance standards were also determined. Results. There were no significant differences between the TP values of the composite resins measured over the backings of plasticine and reflectance standards (p > 0.05). Mean TP values of 1 mm thick bovine enamel, bovine dentin, human enamel and human dentin were 14.7, 15.2, 18.7, and 16.4, respectively, based on the 3 mm round aperture. There were significant correlations between the TP values measured by the two apertures; the bigger the aperture size, the higher the TP value (r = 0.87-0.91, p<0.01). The translucency of enamel and dentin increased in direct proportion to wavelength and in inverse proportion to thickness (r = 0.87-0.91). Mean CR values were negatively correlated with the TP values (r = -0.93 to -0.78). Conclusions. These data could be used as references in the development of esthetic restorative materials and clinical shade-matching.