Influence of Translucency Parameter (TP) on Color Matching Behavior of Dental Composite Materials

Objectives: To determine if TP influences color matching by blending, layering or both using dental composite materials Herculite Ultra (HU) and Estelite Omega (EO).
Methods: Optical characterization of EO was achieved by fitting reflectance curves of layers of uniform thickness to Kubelka-Munk (K-M) reflectance theory to obtain K-M optical absorption (K) and scattering (S) spectra and TP. Cylindrical blending specimens that model a cavity preparation (2mm radius, 1.9mm deep) filled with a composite material were fabricated with various shade combinations. Radiant energy spectra of specimens on black and white backings were obtained in 1 mm increments radially from the center of the specimen. Blending effect (BE) was defined as the CIEDE2000 color difference between measured color and predictions that consider layering alone. CIEDE2000 values of EO were compared with previously determined CIEDE2000 values of HU. CIEDE2000 values were analyzed for dependence on TP.
Results: Mean TP values of 8 different specimens with various combinations of shades were 19.9 (SD 5.2) with a range of 12.6-26.3 for the inner material and 17.5 (SD 4.0) with a range of 12.6-20.4 for the outside material. Mean CIEDE2000 between central position and the theoretical of the outside (ΔETO) indicating color mismatch was 3.8 (SD 1.6) on black and 3.6 (SD 1.6) on white. Mean BE was 0.9 (SD 1.0) on black and 1.3 (SD 1.5) on white. BE was significantly affected by TP of the inner material (P<0.001) and ΔETO was significantly affected by the TPs of the inner (P=0.003) and outer materials (P=0.001) for these models.
Conclusions: Color matching of dental composite materials is influenced by inherent optical properties of the involved dental composite materials.