If there is hidden cavity on the adjacent surface of the tooth, which is not easily perceived by the naked eye and only low density shadow area can be found on the adjacent surface from the X-ray, it is necessary to grind the cavity vertically downward from the jaw surface, remove the decaying matter and fill it with glass ion cementum or composite resin; 2. When the tooth is in pain, after the oral X-ray and CT examination, it is found that there is a coarse lateral root canal that has not been filled, it is necessary to remove the original filling and carry out root canal preparation again to complete the root canal treatment; 3. When the tooth has a hidden fracture or longitudinal fracture, it can be clearly diagnosed by oral 3D CT and immediately extract the affected tooth to completely solve the tooth pain.