Internal bleaching or walking bleach (86)

With root canal treated teeth we often encounter the phenomenon of the tooth being discoloured and greyed.

The internal shape of the root is not a regular circle but a sponge finger shaped cavity. If the dentist fails to adequately cleanse the root canal of the nerve and veins and hermetically seal the cavity, the traffic of tissue fluids and bacteria allows different materials to make their way into the tooth’s crown. These substances (e. g. iron from haemoglobin) render the tooth increasingly more grey. Behind a discoloured tooth the culprit is often an incompletely root-filled or infected root canal.

The same discoloration occurs due to sterile necrosis, when, in the wake of a traumatic event, the tooth pulp atrophies and it is only a few years down the line that the patient realizes that one of their teeth is increasingly more grey and its colour differs from that of its neighbours.

In certain cases, tetracycline (antibiotics) taken in childhood may produce yellowish greyish discoloration.

The correct treatment if such discoloration is performed with what is known as internal bleaching which is different both from at-home whitening carried out with bleaching trays and conventional in-office teeth whitening (Philips Zoom 2). This kind of teeth whitening (walking bleach) can solely be performed on root canal treated teeth. Live teeth cannot be whitened by internal bleaching. The treatment is carried out by the dentist by drilling a hole into the discoloured tooth and completely removing old fillings, left over material and caries and then placing a completely sealing, clean and impeccable root canal filling. A clean, completely sealing root canal filling fills up the entire root canal, which is sealed with a glass ionomer based sealer. Once the root of the tooth is dealt with, the crown is whitened by feeding bleaching gel into the hollow formed in the centre if the tooth and covering it with provisional filling substance. The bleaching substance needs to be replaced daily with fresh, efficient bleach placed inside the crown. This bleach replacement needs to be performed several times over to achieve the desired effect. If need be, internal bleaching may be complemented with the external whitening of tooth surfaces (at-home or in-office whitening).

Central incisor discoloured after root canal treatment:

The infected tooth had to be root-filled and resected, following which periapical bone (the bone around the root) also healed perfectly. Only now could internal bleaching ensue.

How exactly is such teeth whitening performed?

1. First off, a dental examination is due to pinpoint the exact reason for the discoloration of the tooth. At this step radiographs will also be required to assess the quality and condition of the root canal treatment. If the root canal treatment is less than satisfactory, it needs to be repeated, that is, a new root canal filling will be required prior to starting internal bleaching. At our office, today’s widely used internal bleaching technique known as walking bleach is applied. This a reliable and efficient technique of internal beaching which does not require the patient sit for too long a time in the dental chair.
2. Before the placement of bleaching gel (Opalescence Endo) into the tooth, the so-called pulp chamber inside the tooth needs to be cleaned with a drill. Bleaching gel is then placed inside the pulp chamber and the tooth is covered with provisional filling substance. The bleaching gel needs to be replaced several times to achieve the desired results.
3. Following the last bleaching treatment, the tooth is thoroughly cleansed and rinsed, and sealed with provisional filling, since the permanent filling can only be prepared at least 2 weeks after bleaching.

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