DENTAL HARD TISSUE DESTRUCTION 105 



have noted that the lesions, when observed grossh' in tooth seg- 

 ments hke those shown in Fig. 3, may have a multiple, rather 

 rounded, "lacunar" profile, afl^ecting similarly both enamel and den- 

 tin. 



The peripheral surface of the beginning lesion in enamel is ex- 

 tremely hard to detect with the naked eve. With some magnifica- 

 tion, however, as shown in Fig. 4, one may occasionallv detect in 

 the enamel surface, just outside the grossly visible defect, a very 

 slight opacity or chalkiness. Clinically one would be unlikely to 

 diagnose this important incipient stage, because to detect this, the 

 tooth surface would have to be extremely clean, thoroughly dehy- 

 drated, and inspected with a lens under ideal lighting. We shall 

 later discuss the structural basis for this appraisal. Suffice it to say, 

 from the point of \'iew of gross appearance, that if a beginning, 

 posteruptive, chalky lesion in the enamel surface is seen readily 

 with the naked eve prior to gross destruction, one can be reasonably 

 sure that it is probably not erosion, but the beginning of caries 

 (Sognnaes, 1940). 



X-Raij Microscopij 



It would seem a foregone conclusion that if dental erosion were 

 caused purely by mechanical friction, then the surface of the lesion 

 should exhibit a simultaneous and complete removal of all ingre- 

 dients of the tooth substance, inorganic and organic. 



Unfortunately, there is limited knowledge regarding the precise 

 microscopic sequence of events in erosion. Textbooks on the pathol- 

 ogy and histopathologv of the teeth do not include any documentary 

 evidence to indicate that the conclusions have been based on micro- 

 scopic examinations. Indeed, it would appear that the charac- 

 teristics of dental erosion mentioned, for example, in Kronfeld's 

 Histopathologi/ of the Teeth (re-edited by Boyle, 1955) are, in 

 fact, based on the classical gross description of the lesions, stating 

 that the lesions have "sharply outlined borders" and that the "floor 

 is clean, hard and smooth in appearance." 



This is not to say that information is readily obtained by routine 

 histological examination. Neither ground sections nor decalcified 

 sections examined in the optical microscope would in themselves 



