Accuracy and Reliability of Smartphone Virtual Shade-Matching Technique: An In Vitro Study.

Purpose: To determine and compare the accuracy and reliability of shade matching using the conventional and smartphone virtual methods.

Materials and methods: A phantom head with both maxillary central incisors removed was set up. A central incisor of various standard shades was inserted into the phantom head. Five undergraduate and five postgraduate students were asked to select the closest shade to match the central incisor using the Vita Classic shade guide. The procedure was then repeated using images taken by a smartphone. Each technique was repeated three times. Differences in accuracy of shade matching between the two techniques for every shade tab and between undergraduate and postgraduate dental students were compared using chi-square statistical analysis. The P value was set at .001. Differences in intra-rater and inter-rater reliability between the two techniques and among the three sessions were compared using paired t test and analysis of variance (ANOVA), respectively, with a P value of .05. The reliability of both techniques was further measured using Cohen kappa statistical test.

Results: The smartphone virtual shade-matching technique showed significantly higher accuracy in shade matching with most of the tested shade tabs than the conventional method (P < .001), irrespective of observers' clinical experience. Higher repeatability was found in the virtual technique than the conventional technique, with higher intra-rater and inter-rater reliability observed.

Conclusion: Smartphone virtual shade matching showed better accuracy and reliability than the conventional method and could be used as an alternative shade-matching method.