634 THE TEETH. 



is almost, in others perfectly, obliterated. In either ease the effect is, as 

 respects the contraction of the cavity, general, but the local development of 

 dentine continuous with the preexisting tissue is very often coincident with 

 caries. When the crown of the tooth is attacked, the pulp very commonly 

 resumes its formative functions at a point corresponding to that toward 

 which the disease is advancing, and adds, as it were, a patch or plate of new 

 dentine (or secondary dentine, as it is commonly called). 



S. James A. Salter* says: " Considering secondary dentine as applicable 

 to all the after-formations of dentine by which the pulp-cavity is diminished or 

 obliterated, I would subdivide it into dentine of repair, dentine excrescence, 

 and osteo-dentine. I first suggested the arrangement in the ' Guy's Hospital 

 Reports' for 1853. Osteo-dentine and dentine excrescence are not infre- 

 quently seen in teeth that are worn and exhibit dentine of repair. Dentine 

 of repair, however, always forms upon that portion of the pulp-cavity next to 

 the lesion, and is adherent and in direct structural continuity with the pri- 

 mary dentine, whereas osteo-dentine and dentine excrescence occur almost 

 always first toward the extremity of the root, and the former is frequently 

 quite detached from the remainder of the dentine. Mr. Salter asserts against 

 Tomes (page 68), that 'the circumstance of age, per se, is really not efficient 

 for the production of secondary dentine ; and the fact that the teeth which 

 exhibit secondary dentine are usually from aged subjects is merely accidental, 

 and dependent upon the fact that it is in them that the teeth are most worn. 

 Dentine excrescences are little nodules of secondary dentine, occasionally 

 found attached to the interior of the pulp-cavities of teeth which may be 

 otherwise healthy, unassociated -with injury or other disease. Osteo-dentine 

 is a form of secondary dentine in which the tissue combines the characters 

 both of bone and ivory. It is usually vascular ; it is frequently arranged in 

 systems around vessels, like the Haversian systems in bone, and it sometimes 

 contains true lacunae." 



C. Wedl (I. c.) accurately describes the new formations of the hard tissues 

 of the teeth. When speaking of the new formations in the pulp-cavity, he 

 says: "In these cases there occurs a continuous development of dentine 

 within certain limits, determined by an irritation, and the new layers are 

 deposited in immediate contiguity with the old, and in parts are intimately 

 and organically united with the latter. Dentine of this description, which 

 serves as a protective covering of the pulp, is called ' dentine of repair/ 

 'secondary dentine,' as is that dentine, also, which is formed in cases of 

 chronic caries upon that portion of the wall of the pulp-cavity corresponding 

 to the carious locality, and projects into the carious cavity in the form of a 

 spherical segment. In the latter cases, also, we find that the new dentinal 

 canals are continuous with the old ; there is usually an abundant basis-sub- 

 stance, and the canals are separated by quite wide intervals. A different 

 structure is presented by the concentrically laminated forms, two varieties 

 of which are distinguished the simple and complex. ... I have met with 

 a few cases only of true new formations of osseous substance within the par- 

 enchyma of the pulp. The greater portion of the very common osteo-dentine 

 formations is composed of dentine ; the bony substance occurs in a very small 

 quantity, and may consist merely of a group of a few bone-corpuscles. The 

 osseous substance not infrequently attains only a rudimentary development, 

 and resembles that which occurs upon the cement toward the neck of the tooth." 



*" Dental Pathology and Surgery," New-York, 1875. 



