Microstructure of Dental Enamel. I. Organization and Contour of Prisms

¹ Waldemar Medical Research Foundation, Inc., Woodbury, New York

The differential interference, reflected-light microscope provides a simple and elegant method for the study of hard, opaque materials. This microscope system revealed the microstructures of polished human dental enamel with exceptional clarity. Surface contours, Hunter-Schreger bands, and enamel prism boundaries well within the vertical resolution of the objective were easily discriminated. Height differences were detected in the order of hundredths of a micron, and Hunter-Schreger bands and prism boundaries were presented in sharp relief. Longitudinal prism sections were softer and polished away faster than transverse sections. The slopes of Hunter-Schreger bands were transitional cuts. This confirmed the differential polishing rate of enamel prisms. Secondary elevations in Hunter-Schreger bands were observed for the first time. The resultant three-dimensional appearance and color differential supported doubts about the existence of the interprismatic substance and the prismatic sheath. What has been designated as the interprismatic substance appeared to be a continuation of the substance of the adjacent enamel prism. What has formerly been interpreted as a prismatic sheath was revealed to be a prismatic boundary relief. These conclusions are confirmed by fringe displacement under reflected multiple-ray interference microscopy.