Abstract
This study assessed the effectiveness of models for developing subsurface caries lesions in vitro and verified mineral changes by transverse microradiography (TMR). Enamel blocks from permanent (n=5) and deciduous teeth (n=5) were submitted to lesion induction by immersion in demineralizing solutions during 96 h, followed by pH cycles of demineralization (de) and remineralization (re) for 10 days. Two de-/re solutions were tested. Demineralizing solution "A" was composed by 2.2 mM CaCl2, 2.2 mM KH2PO4, 0.05 M acetic acid, with pH 4.4 adjusted by 1 M KOH. Demineralizing solution "B" was composed by 2.2 mM CaCl2, 2.2 mM NaH2PO4, 0.05 M acetic acid and 0.25 ppmF, with pH 4.5 adjusted by 1M KOH. Solution "A" produced cavitated lesions in permanent teeth, whereas solution "B" led to subsurface lesions in deciduous teeth. Solution "B" was then tested in enamel blocks from permanent teeth (n=5) and subsurface lesions were obtained, so that solution "B" was employed for both substrates, and the blocks were treated with slurries of a fluoride dentifrice (1450 ppm F, as NaF, n=5) or a fluoride-free dentifrice (n=5). Solution "B" produced subsurface lesions in permanent and primary teeth of an average (±SD) depth of 88.4µm (±14.3) and 89.3µm (±15.8), respectively. TMR analysis demonstrated that lesions treated with fluoride-free dentifrice had significantly greater mineral loss. This study concluded that solution "B" developed subsurface lesions after pH cycling, and that mineral changes were successfully assessed by TMR.
Highlights
Models based on pH cycling to mimic acid challenges occurring in the oral environment have provided comprehensive knowledge on the onset and progression of dental caries as well as the development of preventive and therapeutic methods [1,2]
Considering the need to establish protocols in which the same methodology could be used for both deciduous and permanent enamel, the aim of this study were to evaluate the effectiveness of the aforementioned pHcycling protocols in developing subsurface lesions in permanent and deciduous human enamel, as well as to demonstrate mineral changes in subsurface lesions after the use of a fluoridated dentifrice (1450 ppm F as NaF) verified by transverse microradiography (TMR)
The glass used for permanent enamel blocks, and was composed by plate was developed for 5 min, rinsed in deionized water, 2.2 mM CaCl2, 2.2 mM KH2PO4, 0.05 M acetic acid, with pH 4.4 adjusted by 1 M KOH
Summary
Models based on pH cycling to mimic acid challenges occurring in the oral environment have provided comprehensive knowledge on the onset and progression of dental caries as well as the development of preventive and therapeutic methods [1,2]. Concerning the methods used to assess mineral loss in in vitro studies, transversal microradiography (TMR) is considered the gold standard [3] This technique can provide data on lesion depth, thickness of the surface layer, integrated mineral loss (ΔZ) and mineral loss according to lesion depth (R). Transverse microhardness is another method that, by means of calculations, can estimate the mineral loss of an artificial lesion. Among the several protocols to induce caries-like lesions in human enamel, two similar models have been tested using different de-/re-mineralizing solutions in permanent [5] and deciduous [6] enamel, employing TMR to quantify enamel mineral changes These protocols seem to be achievable and present a favorable cost-benefit relationship considering de- and re-mineralization solutions. Such solutions have been assessed in a limited number of studies
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