Advancing Visual-Instrumental Agreement in Dental Colorimetry: Development and Validation of Novel Assessment Methodologies

Abstract

This thesis investigates the measurement of tooth colour in restorative dentistry and its relationship to visual perception, challenging longstanding assumptions in dental colour science. While instrumental approaches have traditionally treated tooth colour as a physical property measurable in spaces such as CIELAB or CAM16-UCS, this research emphasises the psychophysical nature of colour perception and the role of parametric effects—such as translucency, morphology, and surface texture—in determining appearance. Through a series of experimental studies, the thesis introduces the Visual Instrument Agreement Scale (VIAS), a novel method for evaluating the congruency between visual assessments and device-based measurements. The research also provides a detailed mapping of the natural tooth colour gamut, identifying 1,173 perceptually unique colours and introducing a compact system of 92 ‘super shades’ capable of minimising shade matching error. Furthermore, the study critically examines the impact of illuminant metamerism and finds it to be clinically negligible in modern materials. In addressing device-dependent variability, this work proposes updated perceptibility and acceptability thresholds and confirms the superior performance of the ∆E*ab colour difference equation for visual-instrumental consistency. These findings support a shift away from rigid notions of “accuracy and precision” and toward perceptually grounded, context-specific evaluation methods in dental colourimetry. This thesis contributes a new framework for shade-matching performance evaluation and offers practical pathways toward digital, shade-guide-free workflows in restorative dentistry