A text-book of dental histology and embryology, including laboratory directions . red a normal condition,and the author has some reason to suppose that the sec-tions showing this condition were from teeth from which thegums had receded and the cementum was destroyed. Thesensitiveness which is so marked in some cases, where thegums have receded beyond the gingival line, is probably dueto the loss of cementum and the uncovering of the granularlayer of Tomes. The cementum is thin and structureless in appearance in the gingival portion when viewed with low powers, but becomes thicker in the apical
A text-book of dental histology and embryology, including laboratory directions . red a normal condition,and the author has some reason to suppose that the sec-tions showing this condition were from teeth from which thegums had receded and the cementum was destroyed. Thesensitiveness which is so marked in some cases, where thegums have receded beyond the gingival line, is probably dueto the loss of cementum and the uncovering of the granularlayer of Tomes. The cementum is thin and structureless in appearance in the gingival portion when viewed with low powers, but becomes thicker in the apical third. In the thicker portions irregular spaces (lacunae) with radiating canals (canaliculi) 3 34 THE DENTAL TISSUES are seen. In life these spaces contain living cells (the cementcorpuscles), which correspond to the bone corpuscles foundin the lacuna of bone. Upon the convex surfaces of the rootthe cementum is thin; upon the concave surface it is increases with age, and so the continuous formation ofcementum tends to round the outlines of the roots and to Fig. 8. \ Gingival line, showing the relation of enamel and cementum. unite them where they approach each other. The fiberswhich are built in the cementum are often imperfectlycalcified, especially where the layers are thick, so that inthe ground sections they may often be easily mistaken forcanals, because the imperfectly calcified fiber has shrunkenin the preparation. ADAPTATION IN DISTRIBUTION OF DENTAL TISSUES 35 ADAPTATION IN THE DISTRIBUTION OF DENTALTISSUES If the teeth of mammals are studied in a comparative waymany modifications will be found in the relative amount anddistribution of the dental tissues, adapting the tooth to per-form special functions. A study of these modified or special-ized teeth will give a better understanding of the functionsof the tissues in the tooth. The human tooth may be takenas a type of omnivorous tooth, and the arrangement anddistribution of its tissues has already been de
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectteeth, bookyear1912
