Evaluation of the fluoride stability of dentifrices sold in Manaus, AM, Brazil

Abstract

ABSTRACT:The minimum requirement for the anti-caries effect of a dentifrice is the presence of available and stable fluoride in the formulation. The concentration of available fluoride in the major dentifrices sold in Brazil has been reported, but few data have been published about its stability, which is temperature-dependent. Thus, the aim of this study was to evaluate the concentration and stability of fluoride in dentifrices sold in Manaus, AM, Brazil, which is a typical tropical city. The concentrations of total fluoride, total soluble fluoride, MFP, and of insoluble fluoride of six Brazilian dentifrices and an imported one were analyzed. The analyses were made when the dentifrices were purchased and during a year of storage at room temperature (28.9 ± 1.16°C) and under refrigeration (26.3 ± 0.88°C). The analyses were performed using an ion specific electrode Orion 96-09. At the time of purchase, all the dentifrices analyzed showed more than 1,000 ppm (mg F -/g; w/w) of soluble fluoride. However, in most of them, this form of fluoride was not shown to be stable. The highest loss of soluble fluoride was found for storage at room temperature, reaching up to 40%. Although all dentifrices comply with the Brazilian guidelines with regard to the concentration of total fluoride (maximum of 0.15%), the instability of soluble fluoride observed in some of them can impair their anti-caries effect and this condition is not contemplated in the Governmental rules. DESCRIPTORS: Dentifrices; Fluorine; Toothpaste; Fluorides. RESUMO:O requisito mínimo para que um dentifrício tenha potencial anticárie é ele ter uma formulação com fluoreto na forma solúvel e estável. A concentração de fluoreto solúvel nos dentifrícios vendidos no Brasil tem sido descrita, mas pouco é conhecido sobre sua estabilidade, a qual é função da temperatura. Assim, o objetivo deste estudo foi avaliar a concentração e estabilidade do fluoreto em dentifrícios vendidos em Manaus, AM, Brasil. As concentrações de fluoreto total, fluoreto solúvel total, MFP, e de fluoreto insolúvel de seis dentifrícios nacionais e um importado foram determinadas quando da aquisição e durante um período de 12 meses de armazenamento à temperatura ambiental (28,9 ± 1,16°C) e sob ar refrigerado (26,3 ± 0,88°C). Para a análise foi utilizado eletrodo específico para íon fluoreto Orion 96-09. Os resultados mostraram que todos os dentifrícios tinham uma expressiva concentração (mg F -/g; p/p) de fluoreto solúvel total quando da aquisição. Entretanto, a maioria deles não se mostrou estável quando do armazenamento. A maior perda ocorreu à temperatura ambiente, atingindo valores de 40%. Embora a concentração de fluoreto total encontrada em todos os dentifrícios esteja de acordo com a portaria da ANVISA, dependendo das condições de armazenamento a perda de fluoreto solúvel pode comprometer o efeito anticárie de alguns dentifrícios e isto não está contemplado pela portaria brasileira em vigor.

Evaluation of fluoride bioavailability in toothpastes

“…Although NaF is known to be incompatible with calcium containing abrasive, its formulation with silica allows fluoride to be soluble 24,26,27) , which can also be supported by the present study's finding with the toothpaste 5. Its measured concentration was 92.48% of the declared, showing the second highest similarity to the declared concentration among the six toothpastes ( Fig.…”

“…SMFP is known to be compatible with a wider range of abrasives than NaF because NaF is incompatible with abrasives that contain calcium; particularly calcium carbonate (CaCO 3 ) and dicalcium phosphate de- hydrate (DCPD). Its fluoride can easily dissociate due to ionic bonding, strongly react with these abrasives, and form insoluble salts [23][24][25] . Meanwhile, the other commonly used fluoride agent SMFP has great compatibility with calcium containing abrasives due to the fluorophosphate (PO 3 F 2 -) component in SMFP 23) .…”

European Organization for Caries Research Workshop: Methodology for Determination of Potentially Available Fluoride in Toothpastes

“…To overcome both limitations, a standardized technique [Cury et al, 2010], adapted from Pearce [1974], has been used for almost 40 years in the Oral Biochemistry laboratory of the Piracicaba Dental School, Brazil [Cury et al, 2004], which was able to demonstrate the results on the availability and stability of fluoride in toothpastes from all over the world [Cury et al, 1981; DOI: 10.1159/000490196 Sarmiento et al, 1994;Conde et al, 2003;Hashizume et al, 2003;Cury et al, 2006;Cury et al, 2010;Carrera et al, 2012;Ricomini Filho et al, 2012;Giacaman et al, 2013;Soysa et al, 2015;Cury et al, 2015. With this technique, it is possible to estimate total, soluble (ionic and ionizable, separately), and unavailable fluoride in toothpastes.…”

Effect of a Fluoridated Food Item on Enamel in situ

“…In this way, the situation in countries where community-based means of fluoridation might be used as an alternative to fluoridated toothpaste as the main source of fluoride delivery was mimicked. In these countries fluoridated toothpaste is either not available, or the fluoride added does not remain [Itthagarun and Wei, 1996;Conde et al, 2003] and/or toothpastes are not affordable for a large population.…”