Fluoride bioavailability on demineralized enamel by commercial mouth rinses

Abstract The ability of mouth rinses, available in the international market, to form reaction products on demineralized enamel (bioavailability test) was evaluated in vitro. Nine mouth rinses purchased in Chile were evaluated; eight formulated with NaF (one containing 100 µg F/mL and seven containing 226) and one with Na2FPO3 (226 µg F/mL as ion F). Demineralized enamel slabs (n=15 per mouth rinse) were sectioned; one half was subjected to the assigned mouth rinse treatment for 10 min and the other half was used to obtain baseline data. Loosely bound and firmly bound fluoride formed on enamel were determined with an ion-specific electrode and the values were expressed in µg F/cm2. The concentration of fluoride and the pH of the mouth rinses were previously determined. Concentrations of loosely bound and firmly bound fluoride formed on enamel were independently analyzed by ANOVA and Tukey's test (α=5%). The loosely bound and firmly bound fluoride concentrations (µg F/cm2) formed ranged from 3.2 to 36.2 and 0.4 to 1.7, respectively. Loosely bound fluoride formed on enamel was significantly more effective in discriminating the effect of different commercial mouth rinses than firmly bound fluoride. Mouth rinses with 226 ppm F as NaF and low pH presented significantly greater bioavailability of fluoride on enamel than those with higher pH or lower NaF concentration. The mouth rinse with Na2FPO3 showed low reactivity. Although further studies are necessary, the findings showed that commercial fluoride-containing mouth rinses have important variations in enamel fluoride bioavailability, which may result in differences on anticaries efficacy.

Resumo Os enxaguatórios bucais comerciais fluoretados diferem na concentração e tipo de sal de fluoreto, no pH e têm alguns ingredientes que podem interferir na reatividade do fluoreto com o esmalte desmineralizado. A capacidade de enxaguatórios bucais comerciais de formar produtos de reação em esmalte desmineralizado (teste de biodisponibilidade) foi avaliada in vitro. Nove enxaguatórios bucais adquiridos no Chile foram avaliados, oito formulados com NaF (um contendo 100 µg F/mL e sete contendo 226) e um com Na2FPO3 (226 µg F/mL como íon F). Os blocos de esmalte desmineralizados (n=15 por grupo) foram seccionados, uma metade foi submetida ao tratamento com o enxaguatório designado por 10 min e a outra metade foi usada para dados baseline. Fluoreto fracamente e firmemente ligados formados no esmalte foram determinados com um eletrodo íon-específico e os valores foram expressos em µg F /cm2. A concentração de fluoreto e o pH dos enxaguatórios foi previamente determinada. As concentrações de fluoreto tipo fluoreto fracamente ligado e fortemente ligado formadas no esmalte foram analisadas independentemente por ANOVA e teste de Tukey (α=5%). As concentrações de fluoreto fracamente ligado e fortemente ligado formados variaram de 3,2 a 36,2 e 0,4 a 1,7, respectivamente. O fluoreto fracamente ligado formado no esmalte foi significativamente mais eficaz para discriminar o efeito dos diferentes enxaguatórios bucais comerciais do que o fluoreto firmemente ligado. Enxaguatórios bucais com 226 ppm F na forma de NaF e baixo pH apresentaram significativamente maior biodisponibilidade de fluoreto no esmalte do que aqueles com maior pH ou menor concentração de NaF. O enxaguatório com Na2FPO3 apresentou reatividade muito baixa. Embora mais estudos sejam necessários, os resultados mostraram que os enxaguatórios bucais comerciais contendo fluoreto apresentam variações importantes na biodisponibilidade do fluoreto, o que poderia resultar em diferenças na eficácia anticárie.

Fluoride bioavailability on demineralized enamel by commercial mouthrinses

Abstract The ability of mouthrinses, available in the international market, to form reaction products on demineralized enamel (bioavailability test) was evaluated in vitro. Nine mouthrinses purchased in Chile were evaluated; eight formulated with NaF (one containing 100 µg F/mL and seven containing 226) and one with Na2FPO3 (226 µg F/mL as ion FPO3 ). Demineralized enamel slabs (n=15 per mouthrinse) were sectioned; one half was subjected to the assigned mouthrinse treatment for 10 min and the other half was used to obtain baseline data. Loosely bound and firmly bound fluoride formed on enamel were determined with an ion-specific electrode and the values were expressed in µg F/cm2. The concentration of fluoride and the pH of the mouthrinses were previously determined. Concentrations of loosely bound and firmly bound fluoride formed on enamel were independently analyzed by ANOVA and Tukey's test (α=5%). The loosely bound and firmly bound fluoride concentrations formed ranged from 3.2 to 36.2 and 0.4 to 1.7, respectively. Loosely bound fluoride formed on enamel was significantly more effective in discriminating the effect of different commercial mouthrinses than firmly bound fluoride. Mouthrinses with 226 ppm F as NaF and low pH presented significantly greater bioavailability of fluoride on enamel than those with higher pH or lower NaF concentration. The mouthrinse with Na2FPO3 showed low reactivity. Although further studies are necessary, the findings showed that commercial fluoride-containing mouthrinses have important variations in enamel fluoride bioavailability, which may result in differences on anticaries efficacy.

Resumo Os enxaguatórios bucais comerciais fluoretados diferem na concentração e tipo de sal de fluoreto, no pH e têm alguns ingredientes que podem interferir na reatividade do fluoreto com o esmalte desmineralizado. A capacidade de enxaguatórios bucais comerciais de formar produtos de reação em esmalte desmineralizado (teste de biodisponibilidade) foi avaliada in vitro. Nove enxaguatórios bucais adquiridos no Chile foram avaliados, oito formulados com NaF (um contendo 100 µg F/mL e sete contendo 226) e um com Na2FPO3 (226 µg F/mL como íon F). Os blocos de esmalte desmineralizados (n=15 por grupo) foram seccionados, uma metade foi submetida ao tratamento com o enxaguatório designado por 10 min e a outra metade foi usada para dados baseline. Fluoreto fracamente e firmemente ligados formados no esmalte foram determinados com um eletrodo íonespecífico e os valores foram expressos em µg F /cm2. A concentração de fluoreto e o pH dos enxaguatórios foi previamente determinada. As concentrações de fluoreto tipo fluoreto fracamente ligado e fortemente ligado formadas no esmalte foram analisadas independentemente por ANOVA e teste de Tukey (α=5%). As concentrações de fluoreto fracamente ligado e fortemente ligado formados variaram de 3,2 a 36,2 e 0,4 a 1,7, respectivamente. O fluoreto fracamente ligado formado no esmalte foi significativamente mais eficaz para discriminar o efeito dos diferentes enxaguatórios bucais comerciais do que o fluoreto firmemente ligado. Enxaguatórios bucais com 226 ppm F na forma de NaF e baixo pH apresentaram significativamente maior biodisponibilidade de fluoreto no esmalte do que aqueles com maior pH ou menor concentração de NaF. O enxaguatório com Na2FPO3 apresentou reatividade muito baixa. Embora mais estudos sejam necessários, os resultados mostraram que os enxaguatórios bucais comerciais contendo fluoreto apresentam variações importantes na biodisponibilidade do fluoreto, o que poderia resultar em diferenças na eficácia anticárie

Fluoride concentration in mouth rinses marketed in Chile and Brazil, and a discussion regarding their legislations

Abstract For fluoride to be effective in controlling caries, it should be bioavailable in commercial products, so that it can be released into the mouth in the products it contains. We chemically determined the available fluoride and pH in nine mouth rinses marketed in Chile, and eleven, in Brazil, and then discussed the legislation in force in both countries, regarding the anticaries potential of these oral hygiene products. The fluoride was analyzed with an ion-selective electrode (F-ISE), using the direct technique. The determinations were made in duplicate, and the results were expressed in ppm F (μg F/mL). The total fluoride concentration found in all the mouth rinses evaluated ranged from 94.7 to 233.5 ppm F, and closely matched what was declared by the manufacturers (100.0 to 226.2 ppm F). However, some mouth rinses showed lower fluoride concentrations (90 and 180 ppm F) in both countries. A Na2FPO3-formulated mouth rinse was found only in Chile, with 216.8 ppm F as the FPO32- ion, and 4.9 ppm F as the F-. The findings show that fluoride was potentially bioavailable in all the mouth rinses evaluated. Regarding the national legislations, although the mouthwashes sold in Brazil comply with the Brazilian legislation, discrepancies were found for Chile. However, neither country had a legislation matching the best available evidence on fluoride mouthwash efficacy for caries control. Thus, some products with low fluoride concentrations (below 226 ppm F), or manufactured with a fluoride salt other than NaF (Na2FPO3) are being sold in the Brazilian and Chilean markets.

Enamel and dentine demineralization by a combination of starch and sucrose in a biofilm - caries model

Abstract Sucrose is the most cariogenic dietary carbohydrate and starch is considered non-cariogenic for enamel and moderately cariogenic for dentine. However, the cariogenicity of the combination of starch and sucrose remains unclear. The aim of this study was to evaluate the effect of this combination on Streptococcus mutans biofilm composition and enamel and dentine demineralization. Biofilms of S. mutans UA159 were grown on saliva-coated enamel and dentine slabs in culture medium containing 10% saliva. They were exposed (8 times/day) to one of the following treatments: 0.9% NaCl (negative control), 1% starch, 10% sucrose, or 1% starch and 10% sucrose (starch + sucrose). To simulate the effect of human salivary amylase on the starch metabolization, the biofilms were pretreated with saliva before each treatment and saliva was also added to the culture medium. Acidogenicity of the biofilm was estimated by evaluating (2 times/day) the culture medium pH. After 4 (dentine) or 5 (enamel) days of growth, biofilms (n = 9) were individually collected, and the biomass, viable microorganism count, and polysaccharide content were quantified. Dentine and enamel demineralization was assessed by determining the percentage of surface hardness loss. Biofilms exposed to starch + sucrose were more acidogenic and caused higher demineralization (p < 0.0001) on either enamel or dentine than those exposed to each carbohydrate alone. The findings suggest that starch increases the cariogenic potential of sucrose.

The effect of fluoride toothpaste on root dentine demineralization progression: a pilot study

The anticaries effect of fluoride (F) toothpaste containing 1100 µg F/g in reducing enamel demineralization is well established, but its effect on dentine has not been extensively studied. Furthermore, it has been shown that toothpaste containing a high F concentration is necessary to remineralize root dentine lesions, suggesting that a 1100 µg F/g concentration might not be high enough to reduce root dentine demineralization, particularly when dentine is subjected to a high cariogenic challenge. Thus, the aim of this pilot study was to evaluate in situ the effect of F toothpaste, at a concentration of 1100 µg F/g, on dentine demineralization. In a crossover and double-blind study, conducted in two phases of 14 days, six volunteers wore a palatal appliance containing four slabs of bovine root dentine whose surface hardness (SH) was previously determined and to which a 10% sucrose solution was applied extra-orally 8×/day. Volunteers used a non-F toothpaste (negative control) or F toothpaste (1100 µg F/g, NaF/SiO2) three times a day. On the 10th and 14th days of each phase, two slabs were collected and SH was determined again. Dentine demineralization was assessed as percentage of SH loss (%SHL). The effect of toothpaste was significant, showing lower %SHL for the F toothpaste group (42.0 ± 9.7) compared to the non-F group (62.0 ± 6.4; p < 0.0001), but the effect of time was not significant (p > 0.05). This pilot study suggests that F toothpaste at 1100 µg F/g is able to decrease dentine caries even under a high cariogenic challenge of biofilm accumulation and sugar exposure.