An evaluation of factors affecting dental shade matching in first-year dental students

Abstract

Statement of problem: Shade selection has become more important and challenging as it becomes more emphasized in esthetic dentistry. It would be beneficial to screen dental students early in their predoctoral education for any deficiencies in color discrimination. Specific tests that reliably predict dental shade-matching ability have not been fully established.

Purpose: The purpose of this study was to determine whether the Farnsworth-Munsell 100 Hue Test (FM-100), Perceptual Ability Test (PAT), ethnicity, age, sex, and time to complete the tests affect dental shade-matching ability and value discernment in first-year dental students. Secondary aims were to determine whether correlations exist between performance on the PAT and FM-100 and between FM-100 and dental shade matching.

Material and methods: The FM-100 test was administered to 98 first-year dental students in a Judge II booth (color temperature=6500 K, color rendering index=90). The Vita Toothguide 3D-Master shade guide was used in this study. For the Value Test, students arranged 3 sets of 5 masked shade tabs from lightest to darkest. In all 3 sets, the value ranged from 1 to 5. In set #1, each shade tab had the same hue and chroma. In set #2, the hues were constant, but the chroma varied. In set #3, the hue and chroma varied. For the Matching Test, students matched together 11 pairs of masked shade tabs from 2 shade guides. Ethnicity (white, African American, Hispanic, Middle Eastern, and Asian), PAT scores, age, sex, and time to complete tests were recorded. Data were analyzed by using least square means, Wilcoxon Rank Sum, Kruskal-Wallis, and Spearman correlation tests (α=.05).

Results: FM-100 total error scores (TES) ranged from 0 to 188. Forty-three students had superior color discrimination (TES 0 to16), 51 had average (TES 20 to 100), and 4 had poor color discrimination (TES>100). Ethnicity, age, and sex did not significantly affect performance on any tests. Longer completion time resulted in better performance on FM-100 (P=.002) and Matching Tests (P=.032). However, increased time resulted in fewer correct answers on the Value Test (P=.016). There was a significant effect of PAT on FM-100 results (P<.001). As PAT scores increased, TES scores decreased, indicating better color discrimination. Similarly, lower TES scores resulted in higher Matching Test results (P<.001). However, this was not observed on the Value Test (P=.302). Correlation between the PAT and FM-100 was weak (r=-0.217), as well as between the FM-100 and Matching Test (r=-0.364).

Conclusions: Ethnicity, age, and sex did not affect dental shade-matching ability. Participants with higher PAT scores demonstrated higher color discrimination on the FM-100 and were better at matching dental shade tabs. Time had different effects on the Matching and Value tests.