Clinical reproducibility of shade measurements using a spectrophotometer

Traditional methods of selecting tooth shades are inconsistent hence reliable, objective methods are needed. OBJECTIVES: to determine whether different dentists obtain the same shade measurements using a spectrophotometer (Crystaleye, Olympus, Japan). METHODS: Sixteen dentists were trained to use the spectrophotometer. They measured the shades of anterior teeth of two patients on two separate sessions. Teeth were kept moist in between measurements to avoid dehydration. Measurements included the CIE L*a*b* coordinates for the cervical, middle, and incisal thirds of twelve teeth (Table below). Measurements were taken thrice and averaged. The following were computed: cervical, body, and incisal D L*a*b* and DEs from the first and second session.

RESULTS: The intraclass correlation coefficients (ICC), computed to determine the inter-reliability of the two spectrophotometers used, were high (>0.9). ICC for measurements taken thrice also were high (>0.9); therefore, averages were used for subsequent calculations and analyses. The mean cervical, body, and incisal L*a*b* values obtained between session 1 and 2 were similar (t-tests, p>0.05), L*a*b* values obtained by the 16 dentists also were similar (ANOVAs, p>0.05). All DE values were below the clinically noticeable threshold of 3.6 (Table).

	Maxillary			Mandibular
	Central Incisor	Lateral Incisor	Canine	Central Incisor	Lateral Incisor	Canine
DE cervical
Patient-1	0.87	0.79	1.09	1.41	1.16	1.87
Patient-2	0.79	0.75	0.80	1.23	1.26	0.91
DE body
Patient-1	0.77	0.53	1.30	0.91	0.99	1.34
Patient-2	0.85	0.56	0.66	1.33	0.71	0.85
DE incisal
Patient-1	1.48	1.16	1.75	1.08	1.06	1.26
Patient-2	0.82	0.74	0.70	1.47	0.69	0.95

CONCLUSION: In this study, dentists trained to use a spectrophotometer obtained similar results. Therefore, using such a device in clinical practice should result in more consistent shade-selection than traditional visual shade-selection techniques.