The purpose of an RCT is to clear the pulp cavity of neurotic tissue and thereby create a complete seal that prevents bacteria from entering and exiting the RC. An RCT may be necessary due to severe caries reaching the RC or a loss of a previous RCT or trauma which will lead to loss of vitality resulting in interruption of blood and/or nerve supply. The RCT can be divided into the following steps:1. Preoperative X-ray A preoperative X-ray provides the dentist with information regarding the RC filling and its subsequent analysis. The dentist is able to see how far the blockage of the RC goes, allows him to identify the orifice of the RC and get an idea on how to negotiate the root canals.15. An example of RC blockage is the appearance of calcification in the RC. Only in rare cases are the blocks unidentifiable. This location and region of the RC block allows the dentist to choose the most effective method to remove everything blocking the RC so that the RCT can begin, for example to be able to treat an RC in a maxillary premolar, access for the Coronal penetration begins in the center of the occlusal surface and following the long axis of the tooth. The RC orifice is identified with an explorer while pressing where the orifice is believed to be located on the x-ray. If there is indeed an orifice, the explorer will move slightly when pressed on the blocked orifice. To minimize perforation and reconfirm the position of the orifice, a second radiograph is taken with the explorer left in place15.2. Coronal preparation/Access Before starting access to the RC, the dentist places a tuber dam – thin sheet of latex – with a hole over the tooth to be treated after having...... half the paper ...... nts new microorganism from entering the RC. Next, a retractor (fine (F) when the master file used was <25 and a less fine retractor (MF for master file larger than 30) is placed into the RC with downward pressure and removed by twisting and turning the retractor towards the wall. This allows the sealant to spread laterally towards the RC walls. The whole process is repeated until now for further scans of the GP point and the entire canal appears pink (pink color of the GP point, suggests). that there are still spaces left and transported, microorganisms or RC may escape. Finally, a hot incubator is used to cut the ends of the GP points that protrude from the RC. But to completely seal the RC, a restoration is placed on the treated RC This completely isolates the RC from the external environment and prevents wear and abrasion of the RC