Histologic Study On the Effects of Fluorine Administered in Dry and Moist Diets on Teeth of Young Albino Rat

Abstract

The histologic effects of a fluorine-containing diet on the incisor teeth of rats have been previously reported by Bergara (1929), Chanales (1930), Pachaly (1932), Bethke, Kick, Hall and Chase (1933) and Schour and Smith (1934). The effects of fluorine injections on the rat incisor and its surrounding tissues were initially reported by Schour and Smith (1934). The reader is referred to Schour and Smith (1934) who have carefully summarized the findings of the various authors. Since the demonstration by the latter authors of the extreme sensitivity of the dental structures to fluorine toxicosis, the rat incisor has been employed by later investigators as a testing medium for various studies in experimental fluorosis. However, in these investigations only the outward gross changes of the incisors have been used for bases of criteria (DeEds and Thomas 1934, Ellis and Maynard 1936, Evans and Philips 1939, Hodge, Luce-Clausen and Brown 1939, Sharpless 1936 and Smith and Leverton 1934). Detailed histologic study, especially of the formative organs of the tooth, has been more or less neglected. Among the more recent literature, the dental histopathology of experimental fluorosis has been reported by Sutro (1935), Ohnell, Westin and Hjiirre (1936) and Brinch (1937). Schour and Smith (1934) and Schour and Hoffman (1939) have also shown, as a result of fluorine injections, that the incremental lines in the enamel and dentin in the rat incisor are indicative of zones of daily growth, 16 microns per day. Both the enamel and the dentin show a pair of light (hypo) and dark (hyper) in-