Root canal treatment is a procedure in which infected or damaged dental pulp is cleaned and the canals are filled. Treatment is generally completed in one or two sessions and is carried out under local anaesthesia. In teeth with extensive loss of structure, reinforcement with a crown after treatment may be recommended in order to reduce the risk of fracture. The outcome of the treatment and how long the tooth remains in the mouth vary according to the level of infection, the remaining tooth structure and the oral care of the patient.