A tooth with neighboring tissues may be compared to a garden tree and neighboring soil. The tree cannot grow on the poor in minerals and rich in parasites soil. Dental plaque is a kind of tooth parasite. It contains different, including pathogenic, microorganisms. The poor soil is circulatory disturbance, systemic diseases. If a plant has healthy roots, but damaged upper part, it may be saved. Tooth root and everything inside of the tooth (canals with nerve fibers and blood vessels) is the pivot of the tooth. Correctly treated canals are the guarantee of further functional renovation of the tooth. Only after completed professional treatment of the tooth root canal and Rtg-examination it is possible to guarantee, that the tooth will remain at its place for the whole life.