ULTRASTRUCTURAL AND CHEMICAL STUDIES ON CARIES 203 



TABLE IV. Composition of Sound and Carious Human Dentin 

 (From Johanseii and Nordbat-k, 1962) 



Or- Inor- 

 Tissue Water ganic ganic — > Ca P JNIg CO2 Ca/P 



Wet weight Ash iveight 



Sound 11.2 20.7 68.1 .37.8 ± 0.83 17.7.5 ± 0..34 1.10 ±0.18 2.20 ±0.37 2.13 ±0.04 



Carious 58.0 27.4 14. G 38.4 ±0.74 18.38 ± 0.42 0.27 ± 0.20 1.07 ±0.36 2.08 ± 0.04 



Dry weight'' 



Sound - 23.0 77.0 27.5 13.0 0.83 3.50 



Carious 65.6 34.4 12.8 6.2 0.10 0.74 



° Organic and bound water. 



* Inorganic composition corrected for CO2 loss (see Fig. 27). 



dicate differences in the location of carbonate in apatite crystallites 

 from these two sources. 



Of particular interest for the interpretation of the electron micro- 

 scopic studies were the observations on the fluoride content of carious 

 dentin. The data presented in Table V show that the inorganic phase 

 of soft carious dentin contains about 10 times more fluoride than 

 the corresponding sound tissue. The high fluoride content might thus 

 be the most important factor in maintaining the crystallites within 

 the carious lesion. 



Studies on trace elements other than fluoride in carious dentin 

 showed a fivefold increase in the zinc content (Table VI). Smaller 



Fig. 22. Section of soft carious dentin decalcified and stained with phos- 

 photungstic acid. The intercanahcular matrix (M) displays collagenous fibrils 

 (CF) in transverse section. Dentinal canals are filled with microorganisms (JB). 

 (X approx. 10,450.) 



Fig. 23. Section of soft carious dentin decalcified and stained with phos- 

 photungstic acid. Collagenous fibrils (CF) with typical banding are found in 

 close proximity to bacteria (B). (X approx. 53,700.) 



Fig. 24. Section of soft carious dentin decalcified and stained with phospho- 

 tungstic acid. Numerous microorganisms (B) are seen within the intercanahcu- 

 lar matrix. A few collagenous fibrils (CF) persist between the microorganisms. 

 ( X approx. 37,300. ) 



Fig. 25. Isolated collagenous fibril from homogenate preparation of carious 

 dentin, exhibiting banding and devoid of crystallites. (X approx. 68,500.) 



Fig. 26. Section of intercanahcular matrix of sound dentin stained with 

 phosphotungstic acid, showing a group of collagenous fibrils with distinct bands 

 and interbands. (X approx. 31,100.) 



