Internal Tooth Bleaching

Internal bleaching treats a tooth that has already had root canal treatment and has darkened since. Conventional teeth whitening works on the outside surfaces of the teeth. Internal bleaching instead places a bleaching agent inside the pulp chamber to treat discolouration that comes from within the tooth.

The procedure uses the access opening made during the original root canal treatment, so no extra drilling into the tooth is usually needed.

Teeth that have had root canal treatment can darken over time for several reasons. Bits of pulp tissue left in the pulp chamber can break down and release pigments into the surrounding dentin. Blood breakdown products from the original injury or treatment can also stain the tooth from within. Sometimes, certain materials used during root canal treatment can add to discolouration over time.

Because this discolouration starts inside the tooth, regular external whitening usually has little effect. The colour change is coming from the dentin and cannot be reached well from the outside.

1. 1

   Access and preparation

   The access opening from the original root canal is reopened. A barrier material is placed over the root canal filling to protect the root from the bleaching agent.

2. 2

   Placing the bleaching agent

   A bleaching agent is sealed inside the pulp chamber, and the tooth is closed with a temporary filling.

3. 3

   Review and repeat if needed

   At a follow-up appointment, the dentist checks how much the colour has changed. The process may be repeated over several visits, depending on how dark the tooth is and how it responds.

4. 4

   Final restoration

   Once the colour has improved enough, the bleaching agent is removed and the tooth is permanently sealed, usually with composite resin.

Internal bleaching can reduce discolouration from within to different degrees. How much the colour changes depends on the type and severity of the discolouration, how long the tooth has been dark, and the individual tooth. Some teeth respond more readily than others.

If bleaching only partly improves the colour, or the tooth does not respond well, other approaches such as composite bonding or a veneer can cover the remaining colour difference from the outside.

Internal bleaching suits a tooth that has darkened after root canal treatment, where the tooth is otherwise structurally sound and the root canal is intact and well sealed. It is not suitable for teeth that are structurally weak, have an active infection, or had inadequate root canal treatment.

An exam and x-rays are needed to confirm it is suitable before starting. If internal bleaching is not right for you, the dentist will go over the alternatives.

If internal bleaching does not change the colour enough, or is not suitable, other options may be considered:

• Composite bonding applied to the front of the tooth to mask remaining discolouration
• A porcelain veneer, which covers the visible surface of the tooth with a thin layer of ceramic

The best option depends on how discoloured the tooth is, its overall condition, and your preferences. The dentist will talk through all the options at your consultation.