Preparation of Ultra-Thin Sections of Mineralized Human Enamel

Abstract

THE preparation of ultra-thin sections of hard substances for electron microscopy without preliminary softening presents special difficulties. The use of industrial diamonds fashioned into knives suitable for cutting hard materials was first described by Fernández-Morán¹. These knives, prepared with a cutting bevel of approximately 50–52°, can be used to cut or cleave thin sections of bone or tooth dentine. The sectioning of hard brittle materials, however, increases the risk of damaging the knife edge from glancing blows, since diamond is itself extremely brittle. The smallest natural cleavage angle obtainable from a diamond depends on the angles formed by the natural crystal planes (this angle is in the region of 70°), consequently in order to construct a diamond knife with the greatest possible edge strength, the two faces of the knife should form this angle. Two diamond knives both with the cutting faces diverging from the knife edge at an angle of 70° were prepared for us several years ago in the Johannesburg research laboratory of the Industrial Distributors, Ltd., under the direction of Dr. J. F. H. Custers and the late Dr. Paul Grodzinski.