Confirmation of theoretical colour predictions for layering dental composite material

A selection of abstracts of clinically relevant papers from other journals. The abstracts on this page have been chosen and edited by John R. Radford.

Abstract

This theory may offer a basis for a computer-based optical measuring instrument, eliminating the need for shade guides.

Main

Mikhail SS, Johnston WM. J Dent 2014; 42: 419–424

Can the application of Kubelka–Munk (K-M) theory be used in shade selections for dental composite resin layering techniques? Simplistically, K-M theory uses '...calculus to solve the differential equations for the change of light fluxes...as a function of scattering, absorption, and distance...' (for background and when applied for enamel and dentine, see J Dent Res 2001; 80: 449–452). In this study, single and double layers of different shades of composite were placed in optical contact with a grey backing. The investigators found disagreements between those values predicted by K-M theory and those measured using the CIELAB and the CIEDE2000 colour difference formulas, concluding that 'colour difference discrepancies generally ranged around the perceptibility threshold'. However, the same group found that K-M theory has provided an accurate model of reflectance for single layers of dental composite and translucent porcelain. It is noted that K-M theory 'assumes an infinitely large diameter layer where there is no accounting for edge effects.'