Color Ranges and Color Distribution of Experimental Resin Composite

Objectives: To analyze color ranges and distribution of UPI Experimental Composite 1.
Methods: A total of 70 tooth shaped specimens (n=5), consisting of an inner dentinal layer (corresponding to one of fourteen shades present on the UPI Experimental Composite 1 (A0.5, A1, A2, A3, A3.5, A4, A5, B0.5, B1, B2, C2, C3, D2, OW), and an outer enamel layer (EN, enamel neutral shade), were fabricated using Ultradent molds (Ultradent Products, South Jordan, UT).
Each layer was polymerized per manufacturer’s instruction through a 1 mm glass slide using a halogen lamp (Valo Grand LED curing light, Ultradent Products, South Jordan, UT). Lamp output was monitored using a radiometer. After polymerization, each specimen was polished with a three step polishing system, course (green), medium (yellow) and fine (white) Jiffy composite polishing discs (Ultradent Products), 20 sec per disc (60 sec total), with mild hand pressure.
Color measurement for was performed using a spectroradiometer (PR-670 SpectraScan, Photo Research, Syracuse, NY). Consistent measurement were enabled using a custom positioning jig made of Clear Bite Matrix impression material (DentMat Holdings, Lompoc, CA). The 50:50% acceptability threshold of 2.7 was used in result interpretation.
Results: Radiance output of the Valo Grand LED curing light ranged from 980 to 990mW/cm². Ranges of L*a*b* color coordinates were 11.4, 4.8 and 9.2, respectively. Mean (sd) differences in L*a*b* values between the adjacent tabs in the same group were 1.2 (0.4), -0.6 (0.4) and -1.6 (1.2). Corresponding color differences were 2.2 (1.0).
Conclusions: L*a*b* coordinate ranges were relatively narrow, partly due to the usage of the same enamel composite for all specimens. Color differences between the adjacent tabs in the same group were below the 50:50% acceptability threshold, indicating consistent color distribution within the groups.