A filling replaces missing tooth structure. If there is decay in a tooth, the Doctor removes the decay and fills the tooth with either amalgam (silver filling material) or composite resin (tooth-colored filling material). If the cavity (decay) is left untreated, then the tooth will likely need a root canal or extracted.
A crown is usually used to strengthen a tooth that has little remaining tooth structure left. A crown can be made from gold, porcelain, or a combination of both.
A sealant is a plastic material that covers the grooves of a tooth to keep decay from starting.
Although teeth hard on the outside, in the middle of the tooth and its roots is the pulp (or nerve). Once this becomes infected or irritated, a root canal may be necessary.
The Doctor will remove the affected pulp or nerve by going through the top of the tooth and using specialized instruments to clean the entire pulp out of the tooth and its roots. The Doctor will then fill and seal the roots. Root canals are usually not painful and only take a little longer than a filling.