Influence of light source and clinical experience on shade matching

Shade is one of the most important attributes when evaluating the success of a restoration. Several factors can influence the visual shade matching process, and therefore the outcome of the final restoration.

1. to assess the importance of clinical experience on shade matching accuracy; 2. to assess the influence of two standard light sources on the ability to match shade tabs; 3. to identify the area in a VITA Classical shade guide where matching errors are most likely to appear.

28 subjects were enrolled in the study: 14 undergraduate dental students and 14 dentists. All subjects had passed the Ishihara blindness test previously. Participants had to match 16 pairs of tabs from two shade guides, under two versions of illuminants of a viewing booth: D50 and D65, on a neutral background, 0°/45° viewing geometry. Paired and independent samples t tests were used to investigate the significant differences between the groups.

The clinical experience had no significant influence on shade matching (p>0.05). According to participants' color discrimination competency, three groups were formed: superior competency, average competency and poor competency. The light source did not significantly influence the matching scores of subjects with superior or average color discrimination competency (p>0.05). However, in the group of subjects with poor competency the light source significantly influenced the results (p<0.05). Moreover, for the group of students the light source also influenced shade matching results (p<0.05). The most frequently mismatched tabs were C2 with D4 (11 subjects - 39.28%), B3 with B4 (11 subjects - 39.28%), B3 with A3.5 (8 subjects - 28.57%).

The light source was proved to influence the shade matching results for subjects with a low level of clinical experience and for subjects with poor competency in color discrimination.