Comparison of Solution- and Gel-prepared Enamel Lesions-an in vitro pH-cycling Study

This study addressed the dose response between fluoride toothpastes and in vitro de- and remineralization, to predict the efficacy of toothpastes and understand the mode of action in the range 0–3,000 ppm F. Enamel lesions were pH-cycled with calcium uptake and loss being assessed daily. Both ‘shallow’ (about 50 µm deep) and ‘deep’ (about 200 µm deep) lesions were studied. F treatments were given in 30 (w/v)% toothpaste dilutions for up to 5 min daily. Calcium loss during the demineralization periods showed a dose response, resulting in 72% reduction for 3,000 ppm F compared to 0 ppm F. Calcium uptake during remineralization was increased in the F compared to non-F groups, with F concentration being less important than its mere presence. Significant differences were observed in F response between shallow and deep lesions, suggesting that this parameter should be included when testing caries-preventive products. Microradiographic analysis showed that lesion depth and severity had increased significantly in the non-F groups. In the F groups, the original lesion was partly remineralized, while a new lesion had formed beyond the original lesion front. Mineral loss of this second lesion correlated inversely with the F concentration of the treatments. These data revealed that fluoride can drive demineralization further into enamel by making the surface tissue less soluble, hence by not neutralizing acids penetrating into the tissue. It is also concluded that depth analysis of mineral uptake and loss is important to understand the mode of action of different F products.

Section: Discussionmentioning

confidence: 66%

The Relative Efficacy of Fluoride Toothpastes Assessed with pH Cycling

Cate

Exterkate

Buijs³

2006

“…Sev eral different versions of the pH-cycling technique have been described [ten Cate and Duijsters, 1982;Featherstone et al, 1986Featherstone et al, , 1988Gcrrard and Winter, 1986;White, 1987;Damato et al, 1988;ten Cate et al. 1988;White, 1988].…”

Section: Introductionmentioning

confidence: 99%

High Resolution Fluoride Profiles of Artificial in vitro Lesions Treated with Fluoride Dentifrices and Mouthrinses during pH Cycling Conditions

Nelson

Coote²,

Shariati³

et al. 1992

A pH cycling model which incorporated a severe demineralization component was used to evaluate fluoride uptake and lesion progression for each of a NaF-based dentifrice, NaF-based mouthrinse and a monofluorophosphate(MFP)-based dentifrice. Simultaneous transverse fluoride and calcium profiles across the resulting artificial lesions were obtained using a proton microprobe technique with a resolution of approximately 10 μm. Longitudinal microhardness testing and proton microprobe calcium profiles were used to determine the extent of lesion progression (ΔZ) with respect to untreated controls. Under the pH cycling conditions of the present study, the NaF dentifrice and mouthwash were observed to have a considerably higher uptake of fluoride in the lesion than the MFP dentifrice. Although the mineral content profiles of the lesions differed for treatments with each of the fluoride products, the differences were not significantly different in this model.

“…In the no-fl uoride group dissolution in the original lesion pH-cycling studies mimic the periodic exposure of enamel and dentine to de-/remineralisation conditions and to fl uoride. In such studies, laminated lesions have been observed [Damato et al, 1988;Arends et al, 1992]. Diffusion of calcium through the lesion, concentration gradients of mineral ions and deposition of mineral and fl uoride determine the overall outcome of the experiments [ten Cate et al, 1995].…”

mentioning

confidence: 99%

Acid Susceptibility at Various Depths of pH-Cycled Enamel and Dentine Specimens

Lagerweij

Cate

2005

pH-cycling and in situ studies have shown that fluctuations in de-/remineralisation conditions or in fluoride usage can lead to laminations inside enamel or dentine lesions. Layers with different mineral content are thought to reflect the history of fluoride administrations. Studying the dissolution properties of such lesions at various depths – using bulk specimens – is presumably hampered by limited diffusion of acids through the lesion pores. Therefore, in this study the acid susceptibility of enamel and dentine lesions and the underlying sound tissues was studied by exposing sections to acid buffers from the cut rather than from the external surface. Specimens were obtained from a previous study of the effects of high-fluoride (0, 1,000, 2,000, 3,000/5,000 ppm F) toothpastes on enamel and dentine de-/remineralisation. Sections were subjected to acid buffers for 3 and 7 days and the changes in mineral content were monitored by contact microradiography. For enamel lesions a significant difference in dissolution over depth was observed between the groups subjected to the different fluoride schemes. At 7 days a dose response was found between the different fluoride groups and the lesion parameters. In the no-fluoride group dissolution in the original lesion and the sound tissue were similar. All dentine lesions which had been treated with fluoride showed inhibition of dissolution, but the inhibition did not increase with higher fluoride concentrations. Deeper into the dentine tissue there was some protection, but it was not statistically significant. We conclude that penetration of fluoride through the lesion pores determines the dissolution pattern of a lesion at various depths.