A text-book of dental histology and embryology, including laboratory directions . Stratification of enamel; the cusp of a bicuspid: De, dento-enamel junction; Ed,enamel defect showing in the heavy stratification band: Ig, interglobular spaces inthe dentine. (About 40 X) 64 CHARACTERISTICS OF THE ENAMEL TISSUE the angle which they form with the axis of the tooth becomesgreater. Any disturbance of nutrition which affects theformation of enamel is always shown in the increased distinct-ness of the bands (Fig. 27). The bands of Retzius, therefore, form a record of theformation of the tissue, and b
A text-book of dental histology and embryology, including laboratory directions . Stratification of enamel; the cusp of a bicuspid: De, dento-enamel junction; Ed,enamel defect showing in the heavy stratification band: Ig, interglobular spaces inthe dentine. (About 40 X) 64 CHARACTERISTICS OF THE ENAMEL TISSUE the angle which they form with the axis of the tooth becomesgreater. Any disturbance of nutrition which affects theformation of enamel is always shown in the increased distinct-ness of the bands (Fig. 27). The bands of Retzius, therefore, form a record of theformation of the tissue, and by their study the points ofbeginning calcification and the manner of the developmentof the tooth crown may be followed. This will be con-sidered again in connection with the grooves, pits, andnatural defects of the enamel. Fig. 28. X Lines of Schreger. (About 5 X) Lines of Schreger.—These are lines appearing in the enamelextending from the dento-enamel junction to or toward thesurface. They are caused by the direction in which theenamel rods are cut. They may be seen in sections, but arebest shown by photographing the cut surface of the enamelby reflected light and with very low magnification. Therods are twisting about each other, and in one streak theyare cut longitudinally, in the next obliquely, and thealternations of these directions cause the appearance ofthe lines (Fig. 28). CHAPTER VI THE DIRECTION OF THE ENAMEL RODS IN THETOOTH CROWN In describing the direction of the enamel rods and theirarrangement in what may be called the architecture of thetooth crown, they are always considered as extending fromthe dento-enamel junction outward. This is not only con-venient, but logical, as they are formed in that way, beginningat the dento-enamel junction and being completed at thesurface. Enamel is formed from
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectteeth, bookyear1912
