What causes tooth staining?
Over time, your teeth can go from white to not-so-bright for a number of reasons. Common reasons include foods and drinks, tobacco, age, medications and trauma. Food and drinks such as coffee, tea and red wine are some major causes of staining. The intense colour pigments of these drinks are called chromogens. The chromogens attach to the white tooth enamel causing it to appear darker.
The chemicals tar and nicotine in tobacco are well known causes of tooth discolouration, turning the teeth a yellowish colour. As people age, the enamel layer can become thinner allowing the inside dentine to show through. Dentine is yellowish in colour and therefore makes the tooth appear darker when the enamel thins.
Injury to the teeth can cause the affected tooth or teeth to become darker over time. The injury can cause the tooth to create more dentine to protect the dental pulp but this can make the tooth visually appear darker. Trauma can also cause blood from inside the tooth to leak into the surrounding tooth structure leading it to appear discoloured.
Some medications are known to cause tooth staining as a side effect. Young children who are exposed to antibiotics like tetracycline and doxycycline when their teeth are forming (either in the womb or as a baby) may have discoloration of their adult teeth later in life.
Stains that are on the outside surface of the tooth are known as extrinsic stains. Examples of causes of these stains can include tea, coffee, red wine and smoking. Depending on the type of staining, it may be able to be removed while brushing with whitening toothpaste as well as professional dental cleaning or by chemical treatment.
Staining that is located inside the tooth's structure is known as intrinsic staining. Potential causes can include medications taken during tooth development, trauma causing blood from inside the tooth to leak into the surrounding tooth structure, amalgam (metal) fillings or root canal treatments.
Removing stains that are based inside the tooth can be very difficult if trying to treat from the outside surface. Depending on the cause of the tooth discolouration, treating the tooth from the inside may be possible.
Teeth that have been injured and undergone root canal treatment may appear discoloured. This is an example of when tooth whitening treatment can be used on the inside of the tooth. The whitening treatment is placed in the centre of the tooth where the dental nerve was once located. It is left inside the tooth for several days before being cleaned out and the tooth fixed with a filling. This treatment is called internal bleaching and can only be done by a dental professional. The internal bleaching treatment may be followed by a crown or veneer treatment.