Dental fillings are often used to replace where a cavity once was. Fillings repair the portion of the tooth that was damaged by the decay process. When fillings become very large, the tooth is often weakened and may break. The most often reason for a crown being recommended in our office is when a cusp, or point breaks off of a back tooth. In short, when a crown is recommended by Dr. Jordan, it is when he anticipates that the remaining tooth left after the decay is removed will be weakened and likely to break. In addition, when a back tooth has had root canal treatment, a crown is recommended to prevent the tooth from breaking.