Endodontics deals with diseases of the dental pulp, which is made of loose connective tissue inside the root canals. The number of canals correlates to the number of tooth roots. The pulp provides nutrients, sensation, and forms secondary dentin for protection. Accessory canals can branch off from the main canal. Proper access cavity preparation is important to allow straight-line access to the canals and apical foramen. Irrigation serves to lubricate, dissolve pulp, wash out debris, and disinfect canals using solutions like sodium hypochlorite and EDTA. New technologies like EndoVac and EndoActivator improve irrigation.