Explain the Failure of Endodontic Treatment

1. Microorganisms are left inside the canal

- Improper/inability of cleaning and shaping,

- Source of infection could be: periapically "by persistent bacteria under the apical area"

or coronally "through the coronal restoration".

2. Missed canal, "like the MM: middle mesial canal",

3. Apical ramification "multiple canals at the apical area",

 ** You have to do good irrigation to reach the areas that could not be reach with the instruments!

4. Perforations with post placement

5. Iatrogenic errors "Over or insufficient obturation".

6. Root canal calcification.