Enamel (the outermost layer of the tooth) is an extremely hard and translucent colourless substance. Enamel wraps around the crown of the tooth and its thickness varies depending on the region of the tooth. The thickest enamel is found on the incisal edges of the front teeth and biting (occlusal) surfaces of the back teeth.
Dentine (the inner layer of the tooth that sits underneath the enamel and that forms the bulk of the tooth including the root) is a hard (similar to bone) substance that is opaque and pigmented substance. Dentine is what gives the tooth its colouration (or chroma).
In young teeth that have not been worn down, the enamel-exclusive zone at the incisal edge is thicker and the translucent zone is prominent. (See the photo above.) This is a beautiful natural feature of virgin teeth.
As the tooth ages and experiences wear, this enamel is worn down and the translucent zone shrinks. In elderly teeth, no translucent zone can be seen. The pictures below show the changes in the incisal translucency with age.
^ Mid-30s
^ Over 60s
Another reason for incisal translucency could be acid erosion of the enamel. This is accompanied by wear of the palatal (inner) surfaces of the incisors.
Progressive destruction of the enamel can be prevented by treating the cause of the erosion (frequent exposure to fizzy drinks, soda, fruit juice; gastroesophageal acid reflux or frequent vomiting). Acid erosion is a condition that your dentist should be able to screen for.
