Todorova A. The features of the microscopic structure, chemical composition, and mechanical properties of dental enamel of the deciduous and permanent human molar teeth

Histological method of research, method of polarizing microscopy, Vickers hardness test, method of comparative dispersion of the double refraction, and statistical method were used to study the features of the enamel rods orientation, chemical composition of the enamel crystallites and enamel microhardness at the different regions of the deciduous and permanent human molar teeth’s crown. It was established the fact of the existence of two main variations of the enamel rods orientation at the distance of 150-250 µm from the outer enamel border – straight-line and arc-shaped. It worth noticing that the arc-shaped type of the enamel rods orientation is almost not observed in the deciduous dental enamel. It was estimated that at the distance of 150-250 µm from the outer enamel border, the regions of enamel, characterized by the arc-shaped type of enamel rods orientation had significantly higher microhardness values that those characterized by the straight-line orientation of the enamel rods. Key words: dental enamel, enamel rods, angles of inclination, chemical composition, microhardness, deciduous molars, permanent molars. Branch-Medicine.