The Influence of Light Quality on Color Matching

Method: 28 subjects were enrolled in the study (n=28): 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 (VITA Classical, VITA, Bad Säckingen, Germany), under two versions of illuminants of a viewing booth: D50 and D65, on a neutral background,  0°/45° viewing geometry (JUST LED Color Viewing Light, JUST Normlicht, Weilheim/Teck, Germany). Student t test was used in order to assess the influence of light source on matching ability.

Result: According to their ability to match shade tabs using the D65 light source (ISO standard TR 28642), participants were divided in three groups: 8 subjects had poor competency (at least 60% of pairs correctly assigned), 10 subjects had average competency (at least 75%) and 10 subjects had superior competency (at least 85%). The light source did not significantly influence the matching ability of subjects from the first two groups (P>0.05). However, for the group of undergraduates the light source significantly influenced the matching (P=0.002). In the group of subjects with poor competency the light source also influenced the results (P=0.008). Clinical experience had no significant influence on the matching ability (P>0.05). The shade tabs most frequently mismatched were C2-D4 (11 subjects), B3-B4 (11 subjects), B3-A3.5 (8 subjects).

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