The root is the foundation of the tooth and from quality of the endodontic treatment depends the life of the teeth. Each of the stages of endodontic treatment (passing, washing, cleansing, filling) is extremely important and each of these stages we performed under optical control - with a CARL ZEISS microscope. The root system's obturation (filling) must be tight, which prevents the infection from reaching the apex of the canal. To do this, we use a hot obturation system, which allows all micro tubules of the root system to be obstructed.