ll'-2 R. F. SOCxNNAES 



Were such calcification defects a primary factor, then erosion would 

 be very widespread. At least it seems unlikely that faulty develop- 

 ment can be blamed for the susceptibility to both erosion and caries. 

 It is a general impression (Bodecker, 1953) that patients with 

 dental erosion as a rule do not suffer from extensive acute dental 

 caries, perhaps suggesting different underlying causes in the pro- 

 duction of these two lesions. 



It is interesting that two reports, by Bird ( 1931 ) and Kronfeld 

 ( 1932 ) , described independentlv the presence of abnormal excessive 

 occlusal wear on the teeth among patients exhibiting dental erosion. 

 Kronfeld even went so far as to relate the wearing facets to precise 

 parts of the teeth, claiming that erosion tended to occur on that 

 part of the tooth which was opposite to the side subject to abnormal 

 wear. In other words, if the wearing facets were found toward the 

 mesial edge of a tooth, the erosion would tend to occur toward the 

 distal portion of the labial or buccal surface. One possible mech- 

 anism in this sequence of events was thought to be an effect of 

 the traumatic occlusion on the pulp, the response of which then 

 might indirectlv affect the dentin structure. One could conceive of 

 changes in the dentinal tubules resulting from changes in the pulp. 



But in this chain reaction, one should perhaps still not overlook 

 the possibility that the abnormal wear may have had an underlying 

 relationship to abnormal salivarv secretion. Undoubtedlv the pres- 

 ence of an adequate flow and consistencv of saliva could have a 

 significant lubricating action during occlusal function. Extreme 

 wear would be expected if completely drv tooth surfaces, unlubri- 

 cated by saliva, were to grind against each other like dry rocks. 



With respect to the indirect secondarv effect of wear on the 

 tooth substance itself by way of a pulpal response, the question 

 has not been ruled out whether the pathogenesis of dental erosion 

 may be related to some peculiar structure of the teeth themselves. 

 We have noted above in our own microradiographic findings that 

 the destruction accompanying erosion rarely penetrates along the 

 dentinal tubules. These are never invaded to any depth by micro- 

 organisms as is found in caries. In other words, the possibility does 

 exist that the tooth substance itself, owing to secondary obliteration 

 of the dentinal tubules, may not give the same access to bacterial 



