Effects of resin cement on the colour of ceramic veneers

Methods: A total of 135 porcelain veneers of shade Vita 1M1 and 1mm thick were produced to fit extracted bovine teeth which had been previously prepared to produce a flat surface. Veneers were positioned on the prepared tooth samples and separated from underlying tooth surface by air (AR), commercially available lubricating gel2 (AG), try-in paste (TP), uncured (UCR) and cured (CR) resin. CIE L*a*b* values were measured and recorded using a spectrophotometer positioned in the middle of the labial face of the veneer. Colour differences (DE) were calculated between the following: AG and TP, CR; TP and CR and between UCR and CR.

Results: Perceptible colour differences (DE>1) were found between CR compared with AG (DE 1.8-4.9); CR and TP of ‘matched' shades (DE 1.05-3.34). Colour differences between UCR and CR were smaller (DE 0.78-1.41), but also in some cases, perceptible.

Conclusions: The shade of underlying try-in paste and resin cement produced perceptible colour shift in the overall veneer restoration in 1mm thick ceramic veneers. This may help when attempting to colour match these restorations to adjacent teeth. Colour differences recorded at the surface of veneer restorations between try-in pastes and their matched resin cements were distinguishable spectrophotometrically at levels that may be clinically perceptible. This latter finding suggests that care should be exercised when using a try-in paste to predict the overall colour of the final restoration.

1 Calibra, Dentsply, UK; Nexus-3 Kerr, Swaziland; Rely-X 3M ESPE, USA.

2 Aquagel® - Adams Healthcare, UK