A text-book of dental histology and embryology, including laboratory directions . e position, when thearea cannot be avoided. In considering the relation of the enamel and dentine, andin studying the arrangement of the enamel rod direction inthe architecture of the tooth crown, it has been pointedout that the dentine cusps and the dentinal marginal ridgesare not directly under the corresponding points on the sur-face of the enamel, but are nearer to the axis of the areas on the surface of the enamel, from the pointdirectly over the tip of the dentine cusp or ridge to the tipof the en
A text-book of dental histology and embryology, including laboratory directions . e position, when thearea cannot be avoided. In considering the relation of the enamel and dentine, andin studying the arrangement of the enamel rod direction inthe architecture of the tooth crown, it has been pointedout that the dentine cusps and the dentinal marginal ridgesare not directly under the corresponding points on the sur-face of the enamel, but are nearer to the axis of the areas on the surface of the enamel, from the pointdirectly over the tip of the dentine cusp or ridge to the tipof the enamel cusps or ridges, become areas of weaknesswhen a cavity is extended into them. Fig. 90 is a photomicrograph of a buccolingual section ofa superior bicuspid, and Fig. 91 is a higher magnificationof the same, made to illustrate the condition. It will be AREAS OF WEAKNESS FOR ENAMEL MARGINS 125 seen that if decay has extended at the dento-enamel junctionto the tip of the dentine cusp, and the enamel walls wereleft in the axial plane, the rods which form the surface of Fig. 90. B A Buccolingual section of upper bicuspid. Enamel is broken from grinding. A to B,area of weakness for enamel margin. (About 20 X) the enamel from the margin of the cavity to the tip of thecusp are not supported by dentine, and would be likelyto be broken and fall away, leaving a defect at the margin Fro. 91
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectteeth, bookyear1912
