The natural colour of teeth is determined by the translucence of the enamel and the thickness of the underlying dentine. [Pichel & Curtis, 1994] Infants' teeth appear whiter because the dentine is thinner, while adult teeth appear more yellow as the underlying colour of the dentine becomes more visible.
Tooth staining can be divided into two types: extrinsic and intrinsic. Extrinsic stain deposits on the surface of the tooth, whereas intrinsic stain is incorporated into the dental tissues. [Nathoo, 1997] It is possible for extrinsic stain to become intrinsic as a result of dentine becoming exposed, or due to defects in the enamel. [Addy & Moran, 1995]
The appeal of "healthy" white teeth is easy to understand in today's modern society and there are a number of whitening procedures and toothpastes that specifically target tooth staining. This section explains more about the different types of tooth staining, how whitening toothpaste and topical treatments work and the issues related to intrinsic tooth whitening and hypersensitivity.
How extrinsic staining occurs and the main substances responsible.
An explanation of pre-eruptive staining compared with post-eruptive staining.
The most common procedure for removing extrinsic staining is the use of toothpastes containing abrasives in combination with surface active agents. This measure can prevent further stain build-up and may remove the stain altogether, depending on the cause of the discolouration.
Bleaching agents used for the removal of intrinsic stain.
How whitening treatments can cause hypersensitivity and irritation in some patients and how to minimise these problems.