File:General and dental pathology with special reference to etiology and pathologic anatomy; a treatise for students and practitioners (1920) (14595942499).jpg

Identifier: generaldentalpat00ende (find matches)
Title: General and dental pathology with special reference to etiology and pathologic anatomy; a treatise for students and practitioners
Year: 1920 (1920s)
Authors: Endelman, Julio Wagner, A. F. (Andrew Fremont), b. 1867
Subjects: Tooth Diseases Pathology
Publisher: St. Louis, Mosby
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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gins to form at birth orslightly before birth, and ends about the twelfth year on the crownof the third molar.4 Dentin As has been previously noted, the dental papilla, or dentin-form-ing organ, makes its appearance about the ninth week, or ap-proximately a few days after the beginning of the formation ofthe dental groove by the inward growth of the dental band.The dental papilla (dentin-forming organ, dental bulb) is a massof embryonal connective-tissue cells (Fig. 114), whose peripheralcells assume a quasicolumnar shape and arrange themselves ina fairly regular way. The cells have a well-defined nucleus 3Tomes: Dental Anatomv, Philadelphia, P. Blakistons Son & Co.4Andrews, R. R.: Dental Cosmos, 1912. MA ELOPMENT OF THE TEETB 247 occupying a position in the interna) third of the cell toward the denial papilla, and differ in appearance as to whether dentin isbeing actively produced or not. During active dentinificationthe ends of the odontoblasts next the already formed dentin are
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Fig. 114.—Same stage of development as seen in the preceding illustration. The fol-licular sac which springs from the base of the dental papilla is seen surrounding the de-veloping organ, a, follicular wall; b, dental papilla; c, internal or ameloblastic layer. expanded; at periods of arrested dentinification the cells seemlonger and their ends more slender and rounded. The processof calcification of dentin (dentinification) which precedes that 248 DENTAL PATHOLOGY of enamel calcification (amelification) by a few days advancesfrom without inwards, the odontoblasts probably discharging thecalcific material so as to envelop the protoplasmic process withwhich each odontoblast is provided at its external end. As cal-cification proceeds, a gradual recession of the odontoblasts oc-curs, and simultaneously with this there is an elongation of theirexternal protoplasmic processes which, occupying the lumen ofthe tubes thus formed, become the dentinal fibers, or fibrilhc, orfibers of Tomes. I

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