Root Canal Therapy is highly successful. Many factors, however, influence the treatment outcome: bone support around the root, forces on the tooth; strength of the tooth including possible fracture lines; shape and condition of the root and nerve canals, etc.
Fractures are one of the main reasons Root Canal Therapy can fail. Cracks that extend from the crown down to the root are visible and hard to detect. They can occur from traumatic injury, biting on hard objects, clenching and grinding habits. Whether the fracture occurs before or after the Root Canal Therapy, the tooth may need to be extracted or referred to a specialist for re-treatment.