The present in situ study investigated the fluoride response of caries lesions with similar mineral loss but two distinct mineral distributions (low- and high-‘R’, calculated as the ratio of mineral loss to lesion depth). Sixteen subjects wore eight gauze-covered enamel specimens with preformed lesions placed buccally on their mandibular partial dentures for periods up to 4 weeks. The participants brushed twice daily for 1 min with an 1,100 ppm F (as NaF) dentifrice. After 3 and 4 weeks, specimens were retrieved and analyzed microradiographically (TMR) and by quantitative light fluorescence (QLF). TMR results revealed that low- and high-R lesions showed opposite behaviors – low-R lesions further demineralized, whereas high-R lesions exhibited some remineralization. In comparison, lesion depth increased in low-R, but remained unchanged in high-R lesions; R decreased in both, but more in high-R lesions; mineral density at the lesion surface remained unchanged in low-R, but increased in high-R lesions. Differences in mineral loss between lesion types increased further between 3 and 4 weeks. QLF did not mirror TMR results as low-R lesions were found to remineralize, whereas high-R lesions remained unchanged. It is likely that low-R lesions differ from high-R lesions chemically and microstructurally; therefore rendering low-R lesion more susceptible to further dissolution. During lesion formation, low-R in contrast to high-R lesions may not lose all of the solubility-determining impurities such as magnesium and carbonate, which can reprecipitate again in different mineral phases within the lesion. In conclusion, mineral distribution at baseline directly impacts in situ lesion response to fluoride.

Keywords:
Demineralization, Fluoride, In situ study, Remineralization
1.
Ando M, van der Veen MH, Schemehorn BR, Stookey GK: Comparative study to quantify demineralized enamel in deciduous and permanent teeth using laser- and light-induced fluorescence techniques. Caries Res 2001;35:464–470.
2.
Aoba T, Yagi T: Crystallographic and structural alterations in the mineral phase of human enamel with carious attacks. J Oral Pathol 1982;11:201–209.
3.
Arends J, Dijkman T, Christoffersen J: Average mineral loss in dental enamel during demineralization. Caries Res 1987;21:249–254.
4.
Brown WE: Solubilities of phosphates and other sparingly soluble compounds; in Griffith EJ, Beeton A, Spencer JM, Mitchell DT (eds): En- vironmental Phosphorus Handbook. New York, Wiley, 1973, pp 203–238.
5.
De Jong ED, Ten Bosch JJ: Error analysis of the microradiographic determination of mineral content in mineralized tissue slices. Phys Med Biol 1985;30:1067–1076.
6.
Driessens FCM, Verbeeck RMH: The probable phase composition of the mineral in sound enamel and dentine. Bull Soc Chim Belg 1982;91:573–596.
7.
Featherstone JD, Duncan JF, Cutress TW: Crystallographic changes in human tooth enamel during in-vitro caries simulation. Arch Oral Biol 1978;23:405–413.
8.
Fujikawa H, Matsuyama K, Uchiyama A, Nakashima S, Ujiie T: Influence of salivary macromolecules and fluoride on enamel lesion remineralization in vitro. Caries Res 2008;42:37–45.
9.
Hafstrom-Bjorkman U, Sundstrom F, de Josselin de Jong E, Oliveby A, Angmar-Mansson B: Comparison of laser fluorescence and longitudinal microradiography for quantitative assessment of in vitro enamel caries. Caries Res 1992;26:241–247.
10.
Hallsworth AS, Robinson C, Weatherbell JA: Mineral and magnesium distribution within the approximal carious lesion of dental enamel. Caries Res 1972;6:156–168.
11.
Iijima Y, Takagi O: In situ acid resistance of in vivo formed white spot lesions. Caries Res 2000;34:388–394.
12.
Iijima Y, Takagi O, Ruben J, Arends J: In vitro remineralization of in vivo and in vitro formed enamel lesions. Caries Res 1999;33:206–213.
13.
Kodaka T, Debari K, Abe M: Hexahedrally based crystals in human tooth enamel. Caries Res 1992;26:69–76.
14.
Koulourides T, Volker JF: Changes of enamel microhardness in the human mouth. Ala J Med Sci 1964;1:435–437.
15.
Laheij AMGA, van Strijp AJP, van Loveren C: In situ remineralisation of enamel and dentin after the use of an amine fluoride mouthrinse in addition to twice daily brushings with amine fluoride toothpaste. Caries Res 2010;44:184–190.
16.
LeGeros RZ: Chemical and crystallographic events in the caries process. J Dent Res 1990;69(special No):567–574; discussion 634–566.
17.
LeGeros RZ, LeGeros JP, Zheng R, Retino M: Magnesium incorporation in apatite and in whitlockite fluoride effect. J Dent Res 1992;71:257.
18.
Lynch RJM, Mony U, ten Cate JM: Effect of lesion characteristics and mineralising solution type on enamel remineralisation in vitro. Caries Res 2007;41:257–262.
19.
Margolis HC, Moreno EC: Kinetic and thermodynamic aspects of enamel demineralization. Caries Res 1985;19:22–35.
20.
Marinho VC: Cochrane reviews of randomized trials of fluoride therapies for preventing dental caries. Eur Arch Paediatr Dent 2009;10:183–191.
21.
Mellberg JR: Relationship of original mineral loss in caries-like lesions to mineral changes in situ. Caries Res 1991;25:459–461.
22.
Mellberg JR: Hard-tissue substrates for evaluation of cariogenic and anti-cariogenic activity in situ. J Dent Res 1992;71(special issue): 913–919.
23.
Mellberg JR, Petrou ID, Grote NE: Findings from an in situ thin-section sandwich model for evaluating cariogenic and anti-cariogenic activity. J Dent Res 1992;71:850–855.
24.
Moreno EC, Zahradnik RT: Chemistry of enamel subsurface demineralization in vitro. J Dent Res 1974;53:226–235.
25.
Poole DF, Shellis RP, Tyler JE: Rates of formation in vitro of dental caries-like enamel lesions in man and some non-human primates. Arch Oral Biol 1981;26:413–417.
26.
Schäfer F, Raven SJ, Parr TA: The effect of lesion characteristic on remineralization and model sensitivity. J Dent Res 1992;71:811–813.
27.
Shellis RP: Relationship between human enamel structure and the formation of caries-like lesions in vitro. Arch Oral Biol 1984;29:975–981.
28.
Shellis RP, Heywood BR, Wahab FK: Formation of brushite, monetite and whitlockite during equilibration of human enamel with acid solutions at 37°C. Caries Res 1997;31:71–77.
29.
Shellis RP: A scanning electron-microscopic study of solubility variations in human enamel and dentine. Arch Oral Biol 1996;41:473–484.
30.
Shellis RP, Wahab FK, Heywood BR: The hydroxyapatite ion activity product in acid-solutions equilibrated with human enamel at 37°C. Caries Res 1993;27:365–372.
31.
Shellis RP, Wilson RM: Apparent solubility distributions of hydroxyapatite and enamel apatite. J Colloid Interface Sci 2004;278:325–332.
32.
Strang R, Damato FA, Creanor SL, Stephen KW: The effect of baseline lesion mineral loss on in situ remineralization. J Dent Res 1987;66:1644–1646.
33.
ten Cate JM: Patient selection and appliance design in intra-oral models. J Dent Res 1992;71(special issue):908–910.
34.
ten Cate JM: The caries preventive effect of a fluoride dentifrice containing triclosan and zinc citrate, a compilation of in vitro and in situ studies. Int Dent J 1993;43:407–413.
35.
ten Cate JM: In situ models, physico-chemical aspects. Adv Dent Res 1994;8:125–133.
36.
ten Cate JM, Dundon KA, Vernon PG, Damato FA, Huntington E, Exterkate RAM, Wefel JS, Jordan T, Stephen KW, Roberts AJ: Preparation and measurement of artificial enamel lesions, a four-laboratory ring test. Caries Res 1996;30:400–407.
37.
White DJ: Use of synthetic-polymer gels for artificial carious lesion preparation. Caries Res 1987;21:228–242.
38.
Zero DT: In situ caries models. Adv Dent Res 1995;9:214–230.
39.
Zero DT, Zhang JZ, Harper DS, Wu M, Kelly S, Waskow J, Hoffmam M: The remineralizing effect of an essential oil fluoride mouthrinse in an intraoral caries test. J Am Dent Assoc 2004;135:231–237.
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2011
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