The method of repairing a tooth with a crack depends on the depth of the crack. If the hidden crack on the surface of the tooth is very shallow and only stays at the level of the enamel, it can be treated without any special treatment or a simple jaw adjustment of the tooth to minimize the occlusal stress will be useful in preventing further expansion of the crack. If the crack of the tooth has reached the dentin, the patient will experience sensitivity to hot and cold stimuli, or even pain when biting hard objects, and the crack needs to be completely abraded and the tooth surface filled with composite resin. If the cracks have reached the pulp cavity or have caused inflammation of the pulp, root canal treatment should be done to remove the infected pulp nerves, and the tooth should be restored with porcelain or all-ceramic crowns to prevent the tooth from becoming brittle and easy to bite fracture or split.