The effect of the substructure on the colour of samples/restorations veneered with ceramic: a literature review

OBJECTIVES: This literature review assessed how changing the metal substructure or ceramic substructure affected the colour of samples or restorations after they have been overlaid by veneering ceramic. SOURCES AND STUDY SELECTION: Studies indexed in journals in MEDLINE were retrieved by searching with the terms "metal, ceramic, substructure, coping, colour and shade." The articles were screened for further relevant investigations. The colour co-ordinates (L*a*b*) and information relating to the substructure and veneering ceramic were recorded or calculated from the relevant articles.

DATA: No clinical studies were identified. It was found that gold-backed samples were lighter and had different a* and b* values from those backed with base metal and silver-palladium. Colour differences were also found between different all-ceramic copings after the application of the veneering ceramic. However, no studies used the same protocol for all-ceramic and metal-ceramic specimens making comparisons impossible. Some of the colour differences observed would have been perceptible in a clinical setting.

CONCLUSIONS: Altering the substructure of an extra-coronal restoration changed its colour. This potentially may lead to additional laboratory and clinical time to produce an aesthetic restoration.