Purpose: To investigate whether viewing distance influences the results of visual tooth color differentiation.
Materials and methods: A total of 65 students underwent both theoretical and practical training by a standardized lecture on the use of an internet learning module (Toothguide Trainer, VITA Zahnfabrik) and a standardized training program (Toothguide Training Box) for visual shade-taking. Each student matched 10 randomly selected shade tabs presented at different viewing distances (arm's length distance [AL, 70 cm] and AL/2 [35cm]) under lateral, non-glare lighting at a 45-degree angle with a color differentiation lamp. The results were recorded as to what extent the presented and selected tabs of the color determination matched.
Results: The overall median values of perceived color difference (ΔE) were 1.6 for AL/2 and 3.2 for AL, and these values were significantly different (P < .001).
Conclusion: Within the limitations of this study, it was shown that the viewing distance had a significant influence on the color deviation in tooth color assessment. Therefore, a smaller viewing distance of 35 cm for shade determination is recommended.
