After root canal treatment, the tooth is weak and brittle. It is weak because the center of the tooth was removed to get at the infected nerve; only the sides of the tooth are left for support. And it is more brittle because the nerve and blood supply are gone.
After a tooth breaks, it is much more difficult to repair. Our Houston dentist, Dr. Minh Nguyen, typically recommends a crown to cover and protect a root canaled tooth. The crown helps to prevent it from breaking.