Abstract
Whatever the technique used for root canal instrumentation, a layer of debris termed “smear layer” is formed. This is a layer composed of an organic and inorganic substance and it harbors bacteria and their by-products. Removing the smear layer enhances the cleaning and disinfecting of root canal walls and grant maximum adaptation of root canal filling materials. Nonetheless, the existence of smear layer can seal the dentinal tubules and decrease the probability of dentinal tubule’s invasion by bacteria and their toxins, this issue is still controversial. Smear layer removal approaches including chemical, ultrasonics, and laser have been widely studied. However, none of them is entirely efficient along the length of all canals or is universally recognized. If the decision was to remove smear layer, irrigating root canals with EDTA followed by NaOCl will fulfill the objective. It is still debatable whether the removal of smear layer will decrease the apical leakage or not. Additional research is required to determine the consequence of removing or preserving the smear layer. Key Words: Endodontic treatment- Smear Layer– EDTA- Ultrasonics- Laser.