Image from page 203 of "A text-book of dental histology and embryology, including laboratory directions" (1912)
Authors: Noyes, Frederick Bogue
Publisher: Philadelphia and New York, Lea & Febiger
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress
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Text Appearing Before Image:
Secondary dentine: A, margin of primary dentine, showing a few of the tubulescontinuing into secondary dentine; P, pulp chamber. (About 80X) this time on the formation of dentine is intermittent, andapparently is the response to some outside condition. Theseconditions may arise in the tooth in which the formationoccurs, or the irritation of one tooth may cause tissue forma-tion in all or part of the others. It has not been determined 186 THE DENTINE whether such reflex trophic stimuli are confined to the samelateral half or the same nerve distribution. Apparently theformation of dentine proceeds again, after a pause, in allteeth. It will seem, therefore, that the mere exposure ofthe entire crown to conditions of thermo-change producessufficient stimulus to the pulp tissue to cause a renewal ofdentine formation. After the first period of rest the dentine Fig. 145
Text Appearing After Image:
A transverse section of a root, showing the reduction in the size of the pulpand formation of secondary dentine. formed in the second period is so nearly identical, and thedirection of the tubules so nearly the same, that it is usuallyimpossible to recognize the junction except at a few pointsin the circumference of a transverse section. After eachperiod of rest, however, the difference in structure betweenthe succeeding portions becomes more marked. Fig. 144 SECONDARY DENTINE 187 shows an area from a longitudinal section when the line Awas the pulpal wall of the dentine. There was probablya considerable period of rest, when for some reason a newformation of dentine was begun. But apparently only someof the odontoblasts took part in the new formation of Fig. 146
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