This can vary according to the complexity of the root canals, the presence of infection, or if re- treatment is being carried out. Sometimes treatment can be carried out in one session lasting between one to two hours. If the canals are heavily infected or are being re-treated, Dr Browne usually treats these teeth over two visits. In these cases, an anti-bacterial dressing is placed in the canals and the tooth is sealed for a period of at least a week and then the treatment is generally completed a second visit.