1. Shape of the Tooth’s Root Canals: Sometimes the tooth may have root canal branches which are difficult to detect. The canals which are curved and branch out often go undetected at times. These undetected branches might be missed in the root canal treatment leading to its failure.(root canal treatment equipment)
2. Unexpected Number of Root Canals: There can be variation in number of canals which are present in the tooth. A tooth might have many small root canals also called as the accessory root canals which may be missed during the treatment. If a canal is missed during root canal treatment, then tooth can become infectious months or years after treatment and in such cases, root canal re-treatment is required.
3. Bacteria in root canal: Certain bacteria are very resistant in nature and no matter what it’s very hard to remove them therefore they easily escape the disinfection by root canal and infection persists.
4. Cracked root: By root canal therapy, roots of the tooth become bit brittle and can fracture on chewing which can further cause failure of root canal treatment. Dental crown after root canal treatment prevents fracture of tooth on chewing. Fracture of the root may occur during root canal treatment procedure and cause root canal treatment failure. It is difficult to diagnose these cracks and these cracks can lead to pain later on.
5. Breakage of file during root canal procedure: Accidental breakage of file during cleaning and shaping of canal during root canal treatment can cause infection in root canal treated tooth and failure of root canal treatment. If canals are sterilized and clean before breakage of file in tooth, then it doesn’t cause any symptom otherwise broken file in canal can lead to pain and infection later on. If file remains in canal before removing the necrotic pulp, then it has to be removed. File in unsterilized canals is to be removed before sealing the root canal treated tooth.