ULTEASTRUCTURAL AND ('HF:^[ICAL STUDIES ON CARIES 197 



TABLE I. Major Elements, Carbonate, and Water Content of 



Sound and Carious Human Enamel" 



(Pit cent dry weight; means of 20 samples. From Singh and Johansen, 



to be pubhshed) 



Ca P Mg CO2 Ca/P HoO 



Sound 



3G.75±().17 17.41 ±0.04 0.54 ± 0.01 2.42 ± 0.02 2.09 ± 0.02 2.02 ± 0.04 

 Cai'ious 



35.95 zt 0.21 17.01 ±0.06 0.40 ± 0.01 1.56 ±0.03 2.08 ± 0.03 3.07 ± 0.05 



" Lesions with intact surfaces (white spots). 



bonate content (Table I). This was particularly noticeable on a 

 volume basis, but the change was also statisticalh' significant on a 

 dry weight basis. The data show that the calcium phosphorus ratio 

 remained relatively unchanged in spite of the demineralization proc- 

 ess. On a percentage basis the loss of carbonate and magnesium was 

 much higher than that of calcium and phosphorus. This finding mav 

 indicate a preferential loss of magnesium and carbonate in the dis- 

 solution of crystallites, or it could possibly reflect a low concentra- 

 tio.n of these ions during the assiuned recrvstallization process. 



Observations on the fluoride content of carious enamel are found 

 in Table IL In study I are presented fluoride values for total lesions 

 compared with a corresponding sample of sound enamel. It can be 

 seen that carious lesions on an ash basis contain 5 times more fluoride 

 than the sound tissues. Since it is known that the fluoride concentra- 



FiG. 9. Section of organic matrix from demineralized carious enamel stained 

 with lead preparation. Rod sheaths (RS) are prominent in outline. Fine fibrils 

 are frecjuentlv missing in interrod areas (/R) but are present within rods (R). 

 ( X approx. 10,500. ) ^ 



Fig. 10. Section of organic matrix from demineraHzed carious enamel 

 stained with lead preparation. An apparent increase in the amount of organic 

 material is observed. ( X approx. 35,650.) 



Fig. 11. Section of organic matrix from demineralized sound enamel stained 

 with lead preparation. The morphologic pattern of the tissue is readily recog- 

 nized bv rods (R), rod sheaths (RS), and so-called interrod areas (/R). (X 

 approx. 8550.) 



Fig. 12. Section of organic matrix from demineralized sound enamel stained 

 with lead preparation. Longitudinallv cut rods (R) delimited by rod sheaths 

 (RS) exhibit a feltwork of minute fibrils. (X approx. 29,200.) 



