Whether or not it is possible to not extract a tooth that is half rotten needs to be decided on a case-by-case basis. If the root of the anterior tooth is long and stable, the decayed tooth tissue can be removed, the infected pulp removed, the root canal treatment completed, the metal or all-ceramic pile core cemented, and finally the porcelain or all-ceramic crown restoration made to preserve the tooth. If the X-rays show that the pulp chamber floor of the molar is intact and there is no large apical shadow, root canal treatment can be performed first and then 2-3 roots can be selected to make pile cores to enhance retention and finally make all-ceramic or metal crown restorations. If the X-rays show that the root canal of the tooth undergoes internal resorption and the apical foramen is open in a flared shape, the prognosis is poor and extraction is required. If the pulp chamber floor of the molar is broken or an apical cyst is formed with significant loosening of the tooth, it cannot be retained and needs to be extracted as soon as possible.