DENTINE 265 



Boll, and others, and upheld by C. S. Tomes in the earlier 

 editions of his Dental Anatomy, where he says : ' The 

 dentine is, I believe, formed by the direct conversion of 

 the odontoblast cells just as the enamel is by the enamel 

 cells, and is derived from them and from them alone.' 

 Schwann also looked upon the dentine as being probably 

 the ossified substance of the pulp, and Waldeyer, considering 

 the process of ossification to be identical with that of 

 ordinary bone, held that the dentinal fibrils are the central 

 remains of the odontoblasts, while their peripheral portions 

 become basis substance. 



The other view, that of secretion, was held by John Hunter, 

 who says, ' The ossified part of a tooth would seem to have 

 much the same connexion with the pulp as a snail has with 

 its shell '. 



Kolliker, Lent, Hertz, and Baume looked upon the forma- 

 tion of dentine as a secretion process. Baume says : ' The 

 odontoblasts secrete a material which calcifies, rather than 

 that they themselves are converted.' 



Tomes, in the later editions of his book, considers that 

 the dentine is calcified by a process of secretion, and follow- 

 ing the previous investigations of Von Ebner and others, 

 the conversion theory of the formation of dentine has been 

 to a great extent abandoned, this conversion theory being 

 that the odontoblast cell becomes actually converted into 

 dentine matrix, its centre remaining uncalcified as the soft 

 fibril, and the rest of the cell forming in different degrees 

 of calcification the Neumann's sheath and the matrix. 

 The view held by the author and by numerous histologists 

 at the present day is that the cells of the pulp secrete 

 a material which calcifies, they themselves not entering 

 into the calcified substance but receding farther and farther 

 into the pulp as calcification advances, and the fibril becomes 

 more and more elongated. 



The Dentine Matrix. Professor von Ebner, in his paper 

 in the Handbuch der Zahnheilkunde, 1891, described the 

 resemblances of dentine to bone : he showed that in decal- 

 cified dentine (treated with hydrochloric acid in a salt 

 solution) a fibrillar structure can be detected, and that by 

 tearing the decalcified dentine the fibrillse could be some- 



