Length determination is a crucial process during root canal treatment because it decides where canal cleaning and shaping ends. Ideally, canal preparation should terminate at the apical constriction, which is the narrowest point of the canal. The apical constriction is usually 0.5mm from the root apex. Clinically, canal length determination can be achieved with an apex locator and reconfirmed radiographically with measured files in canals. A non-vital infected canal harbors millions of microorganisms. Hence, a canal that is prepared short, even by 1mm, will leave behind microorganisms located in the untouched part of the canal, leading to root canal failure. If the working length is too long, there will be a loss of apical stop, causing overextension of root canal filling and micro leakage.
Length determination is a crucial process during root canal treatment because it decides where canal cleaning and shaping ends. Ideally, canal preparation should terminate at the apical constriction, which is the narrowest point of the canal. The apical constriction is usually 0.5mm from the root apex. Clinically, canal length determination can be achieved with an apex locator and reconfirmed radiographically with measured files in canals. A non-vital infected canal harbors millions of microorganisms. Hence, a canal that is prepared short, even by 1mm, will leave behind microorganisms located in the untouched part of the canal, leading to root canal failure. If the working length is too long, there will be a loss of apical stop, causing overextension of root canal filling and micro leakage. 
