ON DENTAL EXOSTOSIS. 37 



morbid condition excited in the pulp through lesion 

 of the crown of the tooth — as for instance in 

 caries, which, as is well known, is one of its most 

 frequent causes. Another source of irritation of 

 the dental pulp, producing exostosis, springs from 

 a wearing down of the crown, which is well exem- 

 plified in this skull of an Esquimaux, where the 

 erowns of the teeth are fully one-third, and many 

 more than half, worn away ; and in those that have 

 been extracted, more or less exostosis will be ob- 

 served (Figs. 1 and 2 ; Plate 5). Similar cases have 

 also presented themselves to my notice among the 

 patients at the hospital, where the teeth, having 

 been much ground down by mastication, have be- 

 come so painful that the patients have urgently 

 requested their removal; but the operation has 

 been rendered tedious and difficult, o>\dng to en- 

 largement of the fang. 



There is, however, another class of cases in which, 

 as John Hunter observes, " the body of the tooth is 

 sound," neither caries nor attrition being present to 

 excite irritation in the pulp, and thus we are neces- 

 sarily driven to the conclusion that the disease arises 

 primarily in the alveolo-dental periosteum. Now this 

 may be occasioned by the tooth having to perform 

 the office of mastication almost or entirely by itself — 

 by being deprived of the assistance of its fellows on 

 that side of the jaw, and sometimes of the other also. 

 We cannot be surprised in such a case if the elastic 

 cushion interposed between the tooth and its bony 



