Tooth decay (clinically known as caries) is not necessarily serious enough to require extraction, but caries filling or root canal treatment can be performed first to preserve the decayed tooth, or extraction if it cannot be preserved. 1. If the tooth is severely decayed but the pulp (i.e., the nerve) has not been damaged, a caries filling can be performed directly. 2. If tooth decay infects the nerve and symptoms of pulpitis occur, root canal treatment can be performed to remove the inflamed nerve, and then caries restoration can be performed to preserve the tooth. 3. If tooth decay causes most of the tooth tissue to be missing or only the root remains, and the tooth cannot be preserved by filling or root canal treatment, then the only treatment option is to extract the tooth. It is recommended to seek medical attention for symptomatic treatment of dental caries to avoid delaying the condition.