When a tooth has sensitivity to hot and cold, pain when biting down or when decay has reached the nerve; a root canal is indicated. There are other reasons as tooth infections that root canal are the only way to eliminate it and save the tooth. After the nerve is removed, roots are filled with “gutta-percha” which is a biocompatible material. In many cases a fiberglass post can be inserted to strengthen the tooth and support a crown over it.