Assessing masticatory performance with a colour-mixing ability test using smartphone camera images

Abstract

Background: Colour-mixing ability tests are frequently used to assess masticatory performance, but the image acquisition process may be cumbersome and technique sensitive. Objectives: To evaluate the reliability of smartphone camera images in assessing masticatory performance using a colour-mixing ability test. Methods: Participants were recruited into three groups of dental state (n = 20 each): fully dentate, removable partial denture wearers and complete denture wearers. After performing a colour-mixing ability test, images of the gum specimens (Hue-Check Gum©) were captured with two smartphones and compared with the images obtained from a flatbed scanner by two examiners. The images were analysed with a subjective- (SA) and an opto-electronical assessment (VoH). Inter- and intra-rater reliability were tested. ANOVA models with repeated measures were used for statistical analysis (⍺ =.05). Results: All three image acquisition techniques were able to distinguish masticatory performance between different dental states. For SA, inter-rater reliability was fair to substantial and intra-rater reliability was substantial to almost perfect. For VoH, inter-rater reliability with the smartphones was at times different between two examiners, but the intra-rater assessment was reliable. The opto-electronic analysis with smartphone images underestimated the masticatory performance significantly when compared to the flatbed scanner analysis. Seven-day ageing of the specimens did not significantly affect the results. Conclusions: The assessment of masticatory performance with the Hue-Check Gum© is a reliable method. The use of smartphones may occasionally underestimate masticatory performance; image acquisition with a flatbed scanner remains the gold standard. A centralised analysis of the photographed wafer may foster the reliability of the diagnosis.