It is not easy to classify the different kinds of dental pigmentations according to intrinsic or external origin, colour, kind or disease.

Teeth absorb through saliva both useful substances that may revitalize enamel, and coloured substances present in foods, beverages, smoke which do not necessarily harm teeth, but that undoubtedly affect their beauty making them appear darker. Furthermore, the usual deterioration of teeth determined by aging certainly accrues these discolorations.

External stains involve tooth enamel only and can be removed with mechanical microabrasion, cavitron, ultrasounds, curettes and polishing with slightly abrasive pastes.

In addition, when stains reach dentin, tooth bleaching is the only aesthetic treatment exerting an oxidising effect on chromophores and on double bonds that makes them partially or totally soluble. The afore said oxidising effect is responsible for curtailing or even making vanish interprismatic stains.

On the other hand, intrinsic stains are much more severe than external stains, and therefore require a professional whitening treatment, that has necessarily to be supervised by a dentist. Intrinsic stains are contained within the enamel and can be classified in:

Prenatal; a disease that affected the mother during pregnancy (rubella, serious anaemia, etc…)

· Genetic: amelogenesis imperfecta or dentinogenesis imperfecta that shows stains involving every tooth.

· Postnatal: they are generally caused by excessive intakes of fluoride or by antibiotics.

· Dental fluorosis: fluorosis can appear under different forms and is most commonly classified in three levels:

1. Normal fluorosis (Smooth, glossy, pale creamy-white translucent surface)

2. Mild fluorosis (Opaque white areas covering less than 50% of the tooth surface)

3. Severe fluorosis (All tooth surfaces affected; discrete or confluent pitting; brown stain present)

Though proper amounts of fluoride guarantee protection against dental caries, an excessive intake of fluoride may cause stains of different colours (brown, grey, white) and tooth surfaces may become extremely pitting, especially during enamel development and calcification during the third and the forth month of pregnancy; then at the age of seven spots and lesions pass from primary to permanent teeth.

Anyway, the frequency of this kind of stains has been recently reduced by the wider knowledge of the side effects of an excessive intake of fluoride.