There are two types of stains that can discolor the teeth. One is called extrinsic: stains caused by substances sticking directly to the surface of the teeth. The most common causes are coffee, tea, and smoking. Extrinsic stains cannot be removed by regular brushing. A regular professional cleaning done by a hygienist or dentist will remove the stains along with any associated bacteria.
The other type of stain is intrinsic or within the tooth. The most common intrinsic staining is characterized by white or yellow spots and sometimes by bands on the teeth. These are usually caused by old fillings that start to leak or change color. Intrinsic discoloration may also form while the tooth is developing. Certain medications may contribute to this problem. The antibiotic tetracycline taken during the years that the teeth are developing will cause the teeth to have a yellowish grey color. It is for this reason that pregnant mothers and children under 9 years of age should not take tetracycline, if at all possible. Some illnesses, when accompanied by a high fever, will also cause this discoloration.
If a tooth starts to turn darker than the adjacent teeth, the cause is likely an abscess or a tooth that has had a root canal treatment. The discoloration is caused by blood inside the tooth being incorporated into the tooth structure. With time, these pigments will move closer to the surface of the tooth, turning it even darker.
Tooth Whitening
To whiten the inherent color of your teeth or to correct an internal stain a bleaching gel can be applied daily.The length of time that the gel is left on the tooth and the frequency of use determines the response that is obtained. It is expected that there will be some improvement within a month of daily application. The bleach will not change the color of existing fillings or crowns. So if these blend with the color of the teeth before bleaching they will not blend afterwards.
The bleaching gel is placed in a splint to keep the gel in proiximity to the teeth. It is possible to target one or two teeth that are particularly discolored by strategically placing the gel in the splint. Sensitivity of the gums or teeth to the gel may result in the get having to be discontinued or limited in use.
A more recent technique for tackling whitening of the teeth is the use of a bleaching gel in combination with a C02 or Nd:YAG laser. The gel is applied to the teeth and a laser light is used to encourage absorbtion into the enamel of the tooth. As this technique is relatively new it is not known what the long term effects on the tooth will be, There may be some risk that the tooth could be damaged in the process.
The dentist also is able to apply a composite bond, a veneer, or a crown to cover intrinsic discoloration. Each of these processes has advantages and disadvantages.
