Apexification is a treatment used to seal an open apex. The apex is the bottom part of a tooth’s root. Your teeth have tiny passageways called root canals. An open apex occurs when the root canals are not closed. Open root canals can lead to pulp exposure and infection. Pulp is the soft substance inside of your teeth. The pulp may be infected if an opening in the tooth allows bacteria inside. An open apex may be found in teeth that are not fully developed. An open apex may result if the root ends are eroded away by a process called resorption. Trauma may also cause an open apex. Ordinarily, pulp infections are treated with a root canal. An apexification is necessary if an open apex makes it too difficult to seal the root end with traditional root canal procedures. An apexification is a procedure that is used to form a hard barrier at the end of a root with an open apex.