MICRO STRUCTURAL CHANGES IN EARLY CARIES 185 



not be reached 

 amel structure. 



not be reached without much greater understanding of normal en 



Summary 



The evidence on the structural changes in demineralization of 

 enamel by dental caries is reviewed. The findings by microradiog- 

 raphy and observations of intrinsic birefringence are in agreement 

 and are accepted by most workers. By the use of form birefringence, 

 spaces caused by the attack can be demonstrated. There is some 

 difference of opinion on the paths of penetration through the enamel 

 surface and on the precise detail and causes of the spread within 

 the enamel, but it is generally agreed that there is a differential de- 

 mineralization of the structures of the enamel. The zones of the 

 enamel are identified and an explanation is offered for their appear- 

 ances. Progressive demineralization is found in the dark zone and 

 the bodv of the lesion and the intermediate zone, well in advance 

 of histologically recognizable organic change. The translucent zone, 

 though occasionally hypermineralized, usually shows a stage of at- 

 tack without evidence of demineralization and because of this may 

 represent a different type of attack. The nature of the attack in this 

 zone is not clear, though suggestions are offered. 



References 



Applebaum, E. 1932. Incipient dental caries. /. Dental Rcseorcli, 12, 619- 

 627. 



Bergman, G., and Engfeldt, B. 1954. Studies on mineralised dental tissues. 

 II. Microradiography as a method for studying dental tissues and its 

 application to the study of caries. Acta Odontol. Scaiul., 12, 99-132. 



Brudevold, F. 1961. Personal communication. 



Crabb, H. S. M. 1962. Areas simulating carious lesion in the enamel of 

 teeth from dentigerous cysts. Intern. Assoc. Dental Research, British 

 Sect. /. Dental Research 41, 1253. 



Darling, A. I. 1956. Studies of the early lesion of enamel caries with trans- 

 mitted light, polarised light, and radiography. Brit. Dental J., 101, 

 289-297. 



Darling, A. I. 1958. Studies of the early lesion of enamel caries, its natunt. 

 mode of spread and points of entry. Brit. Dental J., 105, 119-135. 



