Microstructural Changes 

 in Early Dental Caries 



ARTHUR I. DARLING, rniversity of Bristol Dental School, Bristol, 

 England 



THE first attack of dental caries is usually upon the dental enamel, 

 so that this paper is concerned with caries of the dental enamel. 

 It will also be confined to human dental enamel. 



If one commences with the clinical cavity in the tooth, which is 

 the only clinically identifiable lesion of caries, one can recognize 

 certain histological appearances in the enamel surrounding the cav- 

 itv which are tvpical of enamel caries. These can be traced back 

 through earlier stages and can be identified in lesions in which the 

 enamel surface is still intact. 



It has been known for many years that at least two distinct proc- 

 esses are involved in enamel caries. One of these is demineralization 

 and the other is proteolysis or breakdown of the insoluble keratinous 

 organic matrix of the enamel. So far as can be assessed by histo- 

 logical examination of decalcified sections of enamel caries, the 

 proteolytic changes begin only at or about the time of the break- 

 down of the enamel surface. At this stage there is already consider- 

 able evidence of demineralization of the enamel, and if observations 

 are confined to lesions showing intact enamel surfaces, the com- 

 plications of proteolytic change and bacterial invasion are avoided. 



In such lesions observed in Canada balsam or quinoline by trans- 



171 



