Your teeth are held in their place by roots that extend all the way into your jawbone. Your front teeth usually have one root while other teeth like your premolars and molars may have two or more roots. The tips or the end of the roots are called the apex and this is where the nerves and the blood vessels enter the tooth. These nerves travel through the canal of the root all the way into the pulp chamber. The chamber is found inside the crown which is the part of the tooth that is visible in your mouth.
During root canal treatment, the canals are cleaned and any inflamed or infected tissue is removed. An apicectomy is necessary when infection develops and refuses to go away after a root canal treatment. Root canals are very complex and they have several small branches off the main canal. There are times where even after root canal treatment; there will still be infected debris in the branches. This will prevent healing and may even cause more infections later on. In an apicectomy, the root tip or the apex is removed along with the infected tissue. A filling is placed afterwards so that the end of the root is sealed. Apicectomies are usually referred to as endodontic microsurgery since it is usually done under an operating microscope.