A patient with half of a large tooth decayed off will have to take an x-ray to determine the remaining condition of the root of the tooth through the x-ray. If the decay has not reached the root bifurcation area, the tooth can be preserved, and through regular root canal treatment and standard root canal filling, a fiber post can be placed in the root, on which a resin restoration as well as later tooth preparation and crown restoration can be performed. If half of a large tooth is eroded away and the root bifurcation zone has been injured, resulting in a separation of the roots, the tooth can only be extracted three months after the removal of the affected tooth for conventional restorations, and porcelain fixed bridge restorations or implant restorations can be chosen. Once a tooth has a hole, it is recommended to fill it as soon as possible, do not wait until the hole is getting bigger and bigger, the repair will not only take longer, the cost will also double.