Teeth are made up of three main tissues:
- The outer hard Enamel shell that covers the crown of the tooth and stops it wearing.
- The deeper more resilient Dentine, that gives the tooth it’s strength.
- The dental pulp which is a vital tissue in the middle of the tooth.
Cracks most commonly occur in the outer Enamel layer of the tooth and are most obvious when light shines across the surface of the tooth. This layer is hard and crystalline, and needs to be, due to the fact that it copes with the constant wear and trauma of eating when teeth hit against each other. The enamel shell is bonded to the underlying dentine by a very clever system of collagen fibres and a scalloped surface which stops the outer enamel layer from delaminating, and breaking away.
With trauma – when you get a severe blow on a tooth, and unfortunately with the constant stress of chewing over many years, little crack lines form in the enamel. These are termed ‘infraction lines’. These lines will be worse with people who grind their teeth. Normally they are nothing to worry about because the enamel is still firmly attatched to the dentine. However they can stain over time especially if you drink a lot of coffee or tea.
Although it is more rare, the crack lines can go deeper into the dentine especially if the tooth has lost it’s supporting dentine due to decay. These enamel plus dentine crack lines are generally not visible in front teeth.
There is no way to treat crack lines in enamel. They can only be masked by veneering the tooth with porcelain or composite resin (tooth coloured filling). Dark staining in cracks responds very well to bleaching with Carbamide Peroxide gels that your dentist can dispense.