Dental cosmos . between enamel and cement. The younger the dentine, the thicker are Neumanns sheaths andthe connecting branches. With growing age they decrease in volume,since their superficial layers calcify more and more. The connectingbranches become very thin, especially in the crowns of teeth of olderpersons, and they partially disappear by complete calcification. As HISTOGENY AND HISTOLOGY OF BONY AND DENTAL TISSUES. I28l this calcification goes on, progressing throughout life, the protoplas-mic dentinal processes of the odontoblasts become affected. They arechanged on their surface into
Dental cosmos . between enamel and cement. The younger the dentine, the thicker are Neumanns sheaths andthe connecting branches. With growing age they decrease in volume,since their superficial layers calcify more and more. The connectingbranches become very thin, especially in the crowns of teeth of olderpersons, and they partially disappear by complete calcification. As HISTOGENY AND HISTOLOGY OF BONY AND DENTAL TISSUES. I28l this calcification goes on, progressing throughout life, the protoplas-mic dentinal processes of the odontoblasts become affected. They arechanged on their surface into the dentine ground-substance of Neu-manns sheath, and represent, in the so-called transparent dentine,only extremely thin protoplasmic fibers. I am not able to say whether the dentine ground-substance ofNeumanns sheaths undergoes any chemical change. They are ex-ceedingly resistant to acids, and they are also the last elements to beaffected by caries. I think it very probable that this resisting power Fig. Fig. 17.—Lower jaw of calf, stained with Gerlachs carmine. Ground section treated afterV. Kochs petrifying method and Golgis rapid method. H, Haversian canals in transverse sec-tion ; Haversian canals in longitudinal section ; O, osteoblasts. 300 diam. Drawn from aphotomicro. is caused by some chemical product deposited between the gelatin-yielding fibrils. The calcified ground-substance of the dentine isalso very resistant to acids, although in a less degree than Neumannssheaths. One can best convince oneself of the correctness of the abovedescription by treating with acids a ground section taken throughthe crown of a tooth. The delicate connecting branches betweenNeumanns sheaths are usually invisible if the section is taken froman old tooth. But they appear clearly when, by the application of 1282 THE DENTAL COSMOS. acid, they are rilled up with carbonic-acid gas. The more the decal-cification goes on, the broader become the connecting branches, thedecalcification
Size: 1597px × 1564px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthor, bookcentury1800, bookdecade1890, booksubjectdentistry
