Intraexaminer reliability of measurement of tooth color by spectrophotometry

Objective: To evaluate intraexaminer reliability in measurement of basic tooth color by use of a clinically applicable spectrophotometer. Method and Materials: Three examiners determined the L* (lightness), C* (chroma), and h* (hue) values and tooth color according to the Vita 3D-Master shade guide system (Vident), twice for 161 anterior teeth of 19 subjects by use of a spectrophotometer (Vita Easyshade 1, Vita Zahnfabrik). Between the 2 measurements on each tooth, the investigators had to completely remove the probe tip from the mouth. The reliability of the measurements was observed, and deviations between the 2 L*C*h* measurements, as well as ΔEab for the measurements, were calculated. Results: Exact agreement of chosen shade tab according to the 3D-Master shade guide was achieved in 48% of cases. Mean ΔL*, ΔC*, and Δh* for all examiners were 1.9 (SD 1.7), 1.3 (SD 1.3), and 0.5 degrees (SD 0.7 degrees), respectively. The maximum deviation was 9 for ΔL*, 7 for ΔC*, and 3 degrees for Δh*. Mean ΔEab for the measurements was 2.7 (SD 1.8, range 0 to 9.5). Conclusion: Intraexaminer reliability was usually acceptable, although a clinically relevant difference between the 2 measurements of an examiner was occasionally observed. This uncertainty should be borne in mind in clinical routine and in studies reporting changes in color, eg, studies of tooth bleaching. Keywords: ΔEab value, reliability, shade guide, spectrophotometer, tooth color, tooth-color measurement