Porcelain teeth can be cemented again when they fall out. The reasons for porcelain teeth falling out include cementation failure, occlusal trauma, improper design of porcelain crowns, poor cementation, and poor fit with the dentin, etc. The details are as follows. 1. Failure of cementation: you can remove the residual cementation agent, deal with the cementation surface, and then use better quality cementation material to re-cement. 2. Occlusal trauma: Occlusal trauma caused by early contact may cause the porcelain tooth to loosen and fall off, and it is necessary to re-adhere to the porcelain tooth after adjusting and polishing. 3. Improperly designed porcelain crowns, poor cementation, and poor fit between the tooth and the body: the crown should be redesigned, redesigned and cemented, and prepared for the tooth, and then bonded to a new porcelain crown. If the above symptoms occur, it is recommended to protect the dislodged porcelain crowns and go to the hospital in time for treatment.