If a cavity is sizable, the tooth needs to be strengthened in addition to being filled. This strengthening is achieved by crowning the tooth: the crown covers and protects it.
Bridges are another prosthetic, or replacement, device. When a tooth is lost, the level of pressure on the surrounding teeth changes. With nothing pressing against it, the opposing tooth can even emerge from its socket. Your bite then changes and chewing is affected. A bridge prevents these spacing problems.
When teeth are beyond saving — for example, when advanced periodontal disease means that insufficient bone remains as grounding — a Denture may be a good option. Removing infected teeth and getting an immediate denture will improve the health of your mouth and your sense of well-being.