A text-book of dental histology and embryology, including laboratory directions . eand not the other. In view of these factors it is very neces-sary that a new investigation of the process of enamel for-mation be undertaken, as present knowledge of the processdoes not explain such conditions. Difference in Refracting Index between the Rods and theCementing Substance.—The cementing substance is of slightlygreater refracting index than the substance of the rods. Ifit were not for this it would be impossible to see the rods inunetched sections, either longitudinal or transverse. Theappearance of
A text-book of dental histology and embryology, including laboratory directions . eand not the other. In view of these factors it is very neces-sary that a new investigation of the process of enamel for-mation be undertaken, as present knowledge of the processdoes not explain such conditions. Difference in Refracting Index between the Rods and theCementing Substance.—The cementing substance is of slightlygreater refracting index than the substance of the rods. Ifit were not for this it would be impossible to see the rods inunetched sections, either longitudinal or transverse. Theappearance of striation seen in longitudinal sections is alsodependent upon this difference in action on transmittedlight. CHAPTER V CHARACTERISTICS OF THE ENAMEL TISSUE From what has been said of the structural elements ofthe tissue, their physical and chemical properties, and theirarrangement in the tissue, it is apparent that the strikingcharacteristics of the enamel are the result of these factors;and that it can be intelligently dealt with only by thinking ofit always in these Ename The enamel may be crudely compared to a pavement madeup of tall columns closely cemented together by an inorganiccement. The wear comes on the ends of the columns, andthey furnish great resistance to the abrasion of friction. STRAIGHT ENAMEL 53 When supported upon a good and elastic foundation it is verydifficult to break it down, but when an opening has beenmade in it, and the foundation removed from underneath,the columns are comparatively easily split off and tumbledinto the opening (Fig. 17). This figure is crude, but it is avery helpful one in learning to think of the enamel in termsof its structural elements. Fig. 18
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectteeth, bookyear1912
