Assessment of appearance match by visual observation and clinical colorimetry

Judgments of appearance matching by means of the visual criteria established by the United States Public Health Service (USPHS) and by means of an extended visual rating scale were determined for composite resin veneer restorations and their comparison teeth. Using a colorimeter of 45 degrees/0 degrees geometry and the CIELAB color order system we used the color of the restorations and comparison teeth to calculate a color difference for every visual rating. Statistically significant relationships were found between each of the two visual rating systems and the color differences. The average CIELAB color difference of those ratings judged a match by the USPHS criteria was found to be 3.7. However, the overlap in ranges of the color differences for those comparisons rated matches and mismatches indicates the importance of other factors in appearance matching, such as translucency and the effects of other surrounding visual stimuli. The extended visual rating scale offers no advantages to the more broadly defined criteria established by the USPHS.