Published online Nov 30, 2008.
https://doi.org/10.5395/JKACD.2008.33.6.507
The effect of lactic acid concentration and ph of lactic acid buffer solutions on enamel remineralization
Abstract
There are considerable in vitro and in vivo evidences for remineralization and demineralization occurring simultaneously in incipient enamel caries. In order to "heal"the incipient dental caries, many experiments have been carried out to determine the optimal conditions for remineralization. It was shown that remineralization is affected by different pH, lactic acid concentrations, chemical composition of the enamel, fluoride concentrations, etc.
Eighty specimens from sound permanent teeth without demineralization or cracks, 0.15 mm in thickness, were immersed in lactic acid buffered demineralization solutions for 3 days. Dental caries with a surface zone and subsurface lesion were artificially produced. Groups of 10 specimens were immersed for 10 or 12 days in lactic acid buffered remineralization solutions consisting of pH 4.3 or pH 6.0, and 100, 50, 25, or 10 mM lactic acid. After demineralization and remineralization, images were taken by polarizing microscopy (x100) and micro-computed tomography. The results were obtained by observing images of the specimens and the density of the caries lesions was determined.
As the lactic acid concentration of the remineralization solutions with pH 4.3 was higher, the surface zone of the carious enamel increased and an isotropic zone of the subsurface lesion was found. However, the total decalcification depth increased at the same time.
In the remineralization solutions with pH 6.0, only the surface zone increased slightly but there was no significant change in the total decalcification depth and subsurface zone.
In the lactic acid buffer solutions with the lower pH and higher lactic acid concentration, there were dynamic changes at the deep area of the dental carious lesion.
Figure 1
The white circle indicates surface zone.
Polarizing microscopic observation of demineralized enamel. (Group 1, ×100)
Figure 2
Polarizing microscopic observation of remineralized enamel with 100 mM lactic acid buffer. (pH 4.3 :Group 1)The white arrow indicates isotropic zone.
Figure 3
Polarizing microscopic observation of demineralized enamel. (Group 2, ×100)
Figure 4
Polarizing microscopic observation of remineralized enamel with 50 mM lactic acid buffer. (pH 4.3 : Group 2)
Figure 5
Polarizing microscopic observation of demineralized enamel. (Group 3, ×100)
Figure 6
Polarizing microscopic observation of remineralized enamel with 25 mM lactic acid buffer. (pH 4.3 : Group 3)
Figure 7
Polarizing microscopic observation of demineralized enamel. (Group 4, ×100)
Figure 8
Polarizing microscopic observation of remineralized enamel with 10 mM lactic acid buffer. (pH 4.3 : Group 4)
Figure 9
Polarizing microscopic observation of demineralized enamel. (Group 5, ×100)
Figure 10
Polarizing microscopic observation of remineralized enamel with 100 mM lactic acid butter. (pH 6.0:Group 5)
Figure 11
Polarizing microscopic observation of demineralized enamel. (Group 6, ×100)
Figure 12
Polarizing microscopic observation of remineralized enamel with 50 mM lactic acid buffer. (pH 6.0 : Group 6)
Figure 13
Polarizing microscopic observation of demineralized enamel. (Group 7, ×100)
Figure 14
Polarizing microscopic observation of remineralized enamel with 25 mM lactic acid buffer. (pH 6.0 : Group 7)
Figure 15
Polarizing microscopic observation of demineralized enamel. (Group 8, ×100)
Figure 16
Polarizing microscopic observation of remineralized enamel with 10 mM lactic acid buffer. (pH 6.0 : Group 8)
Figure 17
Demineralized depth at pH 4.3 solutions. (demineralized depth after remineralization/demineralized depth after demineralization) × 100 (%)
Figure 18
Demineralized depth at pH 6.0 solutions. (demineralized depth after remineralization/demineralized depth after demineralization) × 100 (%)
Figure 19
Surface lesion depth of dental carious in enamel at pH 4.3 solutions.(depth of surface lesion after remineralization/depth of surface lesion after demineralization) × 100 (%)
Figure 20
Surface lesion depth of dental carious in enamel at pH 6.0 solutions.-(depth of surface lesion after remineralization/depth of surface lesion after demineralization) × 100 (%)
Figure 21
Comparison of density in enamel before and after remineralization with 100 mM lactic acid buffer by micro-CT. (pH 4.3 : Group 1)
Figure 22
Comparison of density in enamel before and after remineralization with 50 mM lactic acid buffer by micro-CT. (pH 4.3 : Group 2)
Figure 23
Comparison of density in enamel before and after remineralization with 25 mM lactic acid buffer by micro-CT. (pH 4.3 : Group 3)
Figure 24
Comparison of density in enamel before and after remineralization with 10 mM lactic acid buffer by micro-CT. (pH 4.3 : Group 4)
Figure 25
Comparison of density in enamel before and after remineralization with 100 mM lactic acid buffer by micro-CT. (pH 6.0 : Group 5)
Figure 26
Comparison of density in enamel before and after remineralization with 50 mM lactic acid buffer by micro-CT. (pH 6.0 : Group 6)
Figure 27
Comparison of density in enamel before and after remineralization with 25 mM lactic acid buffer by micro-CT. (pH 6.0 : Group 7)
Figure 28
Comparison of density in enamel before and after remineralization with 10 mM lactic acid buffer by micro-CT. (pH 6.0 : Group 8)
Table 1
Initial composition of demineralization solution
Table 2
Initial composition of remineralization solutions
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