2 things may happen...
1. If you have chipped off just a small piece of tooth enamel, the dentist may repair the damage with a filling. If the repair is to a front tooth or can be seen when you smile, the dentist will likely use a procedure called bonding, which uses a tooth-colored composite resin.
Bonding is a simple procedure that typically does not require numbing the tooth. To bond a tooth, the dentist first etches its surface with a liquid or gel to roughen it and make the bonding material adhere to it. Next, the dentist applies an adhesive material to the tooth followed by a tooth colored resin. After shaping the bonding material to look like a natural tooth, the dentist uses an ultraviolet light to harden the material.
2. If a large piece of tooth breaks off or the tooth has a lot of decay, the dentist may grind or file away part of the remaining tooth and cover it with a crown, or tooth-shaped cap, made to protect the tooth and improve its appearance. Permanent crowns can be made from metal, porcelain fused to metal, all resin, or all ceramic. Different types have different benefits. All-metal crowns are the strongest. Porcelain and resin crowns can be made to look nearly identical to the original tooth.
If the entire top of the tooth is broken off but the root is still intact, the dentist may perform root canal therapy and place a pin or a post in the canal, and then build up enough of a structure onto which a crown can be made. Later, the dentist can cement the crown over the pin or post-retained restoration.
Dr. James L. Johnson