Influence of illumination conditions on color differences among visual, intraoral scanner, and spectrophotometric tooth shade determination methods: a prospective clinical study

In this study, color differences among shade measurements obtained using a visual assessment method, an intraoral scanner, and a spectrophotometric imaging system were evaluated. Additionally, the influence of daylight and fluorescent illumination conditions on intermethod color differences was investigated. Shade measurements of maxillary central incisors were performed using three shade determination methods: visual assessment, intraoral scanning, and spectrophotometric imaging-based measurements. These measurements were obtained under standardized daylight and fluorescent lighting conditions. Color differences were calculated using the CIEDE2000 color difference formula. Statistical analyses were performed using nonparametric tests at the 0.05 significance level. Significant differences among shade-determination methods were observed under daylight conditions, whereas none were detected under fluorescent lighting. Illumination conditions significantly influenced color differences associated with visual and intraoral scanner-based measurements. Spectrophotometric imaging-based measurement demonstrated consistent results across illumination environments. Shade-determination outcomes were influenced by both the measurement method and the illumination condition. Visual and intraoral scanner-based measurements exhibited greater sensitivity to lighting variations, whereas spectrophotometric imaging-based measurements remained stable. These findings emphasize the importance of illumination standardization in clinical shade selection procedures.