The effect of lactic acid concentration and ph of lactic acid buffer solutions on enamel remineralization

Jung-Won Kwon; Duk-Gyu Suh; Yun-Jung Song; Yun Lee; Chan-Young Lee

doi:10.5395/JKACD.2008.33.6.507

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Kwon, Suh, Song, Lee, and Lee: The effect of lactic acid concentration and ph of lactic acid buffer solutions on enamel remineralization

Original Article

Journal of Korean Academy of Conservative Dentistry

Journal of Korean Academy of Conservative Dentistry 2008; 33(6): 507-517.

Published online: 30 November 2008

DOI: 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

Jung-Won Kwon, Duk-Gyu Suh, Yun-Jung Song, Yun Lee, Chan-Young Lee

Department of Conservative Dentistry, College of Dentistry, Yonsei University, Korea.

Corresponding Author: Chan-Young Lee. Department of Conservative Dentistry, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-Ku, Seoul, 120-752, Korea. Tel: 82-2-2228-8700, Fax: 82-2-313-7575, chanyoungl@yumc.yonsei.ac.kr

Received 21 May 2008 Revised 1 September 2008 Accepted 4 September 2008

(open-access):

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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.

Keywords: Dental caries, Demineralization, Remineralization, Lactic acid, pH, Polarizing microscopy, Micro-computed tomography

Figures and Tables

Figure 1

Polarizing microscopic observation of demineralized enamel. (Group 1, ×100)

The white circle indicates surface zone.

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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