At times, the decay or fracture may be serious enough that it affects the integrity of the tooth and root structure. Root canal treatment will not be suitable in such cases as there is a possibility of failing.
A more suitable alternative would be dental extraction, where your tooth is extracted and replaced with a denture, bridge or implant. This helps to restore chewing, prevent shifting of teeth and reduce risks of gum diseases.
However, root canal treatment is the preferred treatment (if possible) as it fixes your natural tooth.