[Mechanical properties and acid solubility of the dental surface. I. Microhardness]

The present paper deals with the relationship between microhardness, and the circumferential as well as radial location of the test points on the tooth surface. The measurements did not indicate a significant correlation between the average hardness of the tooth sections, and their location on the circumference. The average hardness of the sections on one probe, however, showed a large variation. Hardness was also correlated with the distance from the enamel surface. There was a steep hardness gradient in the outermost 50 micrometer thick enamel layer: hardness increased in the direction to the dentino-enamel junction. The investigated enamel layer seems to be layer of less mineralized enamel which might have its origin in de-, and remineralization processes on the enamel surfaces.