In situ Evaluation of Sodium Hexametaphosphate-Containing Dentifrices

Abstract

The purpose of this investigator-blinded, five-treatment, crossover human intraoral study was to evaluate the effects of two experimental dentifrice formulations containing either stannous fluoride (SnF₂) or sodium fluoride (NaF) packaged with sodium hexametaphosphate in a dual-phase delivery system on demineralization-remineralization using an in situ model system. The experimental dentifrice formulations’ ability to alter demineralization-remineralization was compared to a series of three controls: SnF₂-positive control, NaF-positive control and no-fluoride placebo-negative control. The single-section crown model, developed at the University of Iowa, was used to assess the fluoride efficacy of two experimental products versus the placebo containing no fluoride and positive controls. The results of the current in situ study suggest a clinical level of anticaries activity for the experimental SnF₂ and NaF dentifrice formulations that was as good as either of the positive controls, when evaluated using polarized light microscopy. This supports the conclusion that the use of the sodium hexametaphosphate ingredient does not interfere with the normal fluoride activity of these toothpastes. In addition, the experimental SnF₂ product was numerically better than both the NaF and placebo controls at preventing demineralization of sound root surfaces.

Effect of an Alcohol-Free, 1% Chlorhexidine Gel as an Adjunct to a Fluoridated Dentifrice Using an Intraoral Crown Model

“…In this table, smaller numbers indicate a greater anticaries effect of the test product. The placebo dentifrice nearly doubled the lesion area when compared to the 1,100 ppm F + chlorhexidine dentifrice (p = 0.0007), as is commonly observed with this model system [Wefel et al, 2002], and the lesion area was significantly larger in the placebo group than in the 1,100 ppm F group (p = 0.0008). However, the differences between the 1,100 ppm F dentifrice and 1,100 ppm F + chlorhexidine in this study were not greater than what could be expected by chance (p = 0.99).…”

“…Sample size estimates were calculated based on means and standard deviations from a previous study which utilized the same model and similar test products [Wefel et al, 2002]. A sample size of 24.1 and 28.4 for enamel and root tissue data, respectively, was required for a desired power of 80% at a level of significance of p !…”

“…Because of pretreatment area differences among treatments for enamel caries, comparisons among treatments for differences in change in area for enamel caries were performed using ANCOVA, with pretreatment area as a covariate. Earlier work using the same model system has demonstrated that there are no statistically significant carryover effects due to fluoride-containing treatments for any specimen type; therefore, the statistical design in this study did not include a term for treatment sequence or study period [Wefel et al, 2002]. Carryover effects of chlorhexidine was a concern, so the 1,100 ppm F + chlorhexidine treatment combination was provided to all participants during the final study period of this modified crossover design.…”

“…The in situ model provides an opportunity to use more sensitive and sophisticated laboratory techniques than the caries detection techniques currently available clinically, while taking advantage of using a 'natural' environment consisting of dietary factors, oral microflora, and host factors such as saliva. Since the same tooth sections are evaluated during a specific treatment period, there would be no assumptions about whether or not observed changes are real or inferred, and each section can serve as its own control allowing interpretation of any changes in lesion appearance to be the result of handling and oral exposure [Wefel et al, 2002].…”

The Relative Anticaries Effectiveness of Three Fluoride-Containing Dentifrices in Puerto Rico

“…The invention of stabilized stannous fluoride dentifrice formulations in the mid-1990s was a major technical advance because it significantly increased the available amount of soluble fluoride (close to 100% theoretical) in the dentifrice formulation, which in turn resulted in improved anticaries performance with respect to fluoride uptake and inhibition of microbial carbohydrate metabolism mediated through the stannous fluoride [White, 1995]. Recently, an experimental 0.454% stabilized stannous fluoride with sodium hexametaphosphate dentifrice was reported to deliver statistically significantly superior prevention of demineralization of sound dentin relative to a control dentifrice in an in situ caries model [Wefel et al, 2002]. In addition, data from clinical studies involving humans at risk for root caries supports the enhanced ability of stannous fluoride-containing formulations (gels, dentifrices, rinses) to reduce root caries compared to sodium fluoride control formulations [Al-Joburi et al, 1991;Nemes et al, 1992].…”