Large decay of tooth structure that is not treated in time may advance into the nerve chamber inthe center of tooth structure. This cause infection of the nerve that causes severe pain that can also results in acute swelling. Root canal is basically removal of infected nerve within the tooth structure, clean and disinfect the canal space and fill it with polymeric materials to seal the canalspace. At my office, the assessment for the root canal therapy is made to determine, 1) if root canal is a right choice of treatment, 2) if it is, assess if the procedures will require special equipments such as high power microscopes. If the procedure will require such equipments, the case is referred to a root canal specialist. 3) if the case does not require such equipments, the procedure is rendered at the office by Dr Kang.