A text-book of dental histology and embryology, including laboratory directions . Molar. In the corner the stage micrometer shows XTTTT °f a millimeter drawnwith the same lens. The field shows the branching of a bloodvessel andthe connective-tissue cells of the pulp. Drawn from i oil-immersionlens with camera lueida. (About 12,000 X) ATROPHY 161 Character of the Effect on the Tissue.—In atrophy the for-mation of the rods is first affected, the cementing substancebecoming greater in amount. Conditions which produceslight disturbances are marked simply by a prominent bandof Retzius. These are il
A text-book of dental histology and embryology, including laboratory directions . Molar. In the corner the stage micrometer shows XTTTT °f a millimeter drawnwith the same lens. The field shows the branching of a bloodvessel andthe connective-tissue cells of the pulp. Drawn from i oil-immersionlens with camera lueida. (About 12,000 X) ATROPHY 161 Character of the Effect on the Tissue.—In atrophy the for-mation of the rods is first affected, the cementing substancebecoming greater in amount. Conditions which produceslight disturbances are marked simply by a prominent bandof Retzius. These are illustrated in Figs. 125 and 126. Insuch sections the globules of which the rods are composedare more imperfectly fused and the difference in the refractingindex between the rod substance and the cementing substanceis greater. The cementing substance also seems to containactual pigment. The zone of dentine which was being formedat the same time usually shows a zone of interglobular spaces,the character of which will vary with the character of thedefect in the enamel. Fig. 125. Labial surface of a central incisor, showing atrophy grooves. The stain in the groovemakes it appear deeper than it is. Fig. 126 is a part of a section from this tooth. In strongly marked cases it appears that no enamel at allis formed during a longer or shorter period, and when forma-tion begins again the portion that should have been formedis left out and the new formation is telescoped on to the the pathological condition begins to affect the enamel-forming organ, the rods are more and more imperfectlyformed and finally disappear, cementing substance contin-uing to be deposited. The entire crown, therefore, is short-ened and has the characteristic stunted appearance. Thiswill be understood by a study of Figs. 127, 128, and the surface of the tooth, where the new formation joins11 162 THE EFFECT OF CARIES ON THE ENAMEL the old, there is a groove the depth of which is determinedpartly by
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectteeth, bookyear1912
