The Effects of 1% Pyrophosphate and 0.02% Sodium Fluoride on Artificial Caries Lesions in vivo

Abstract

We evaluated the potential of a pyrophosphate-fluoride solution to affect the remineralizing-demineralizing equilibrium, i.e., caries-inhibiting/-promoting effects on enamel in vivo. Fifteen subjects carried dentin blocks and enamel thin sections with artificial caries lesions in removable partial dentures for periods of two weeks, during which time they rinsed twice daily in a double-blind, randomized cross-over design with solutions containing (a) 90 ppm F, (b) 90 ppm F and 1% pyrophosphate, or (c) no active agents (placebo). A severe cariogenic challenge provided to the lesions by plaque under a stainless steel mesh cover resulted in the placebo-treated lesions losing 70.2% +/- 72.1% mineral. The pyrophosphate rinse with fluoride held the mineral loss to only 28.1 +/- 52.8%, while the fluoride rinse without pyrophosphate held the loss to 24.2 +/- 50.1%. The differences between the fluoride and placebo results were significant (p less than 0.01), but the difference between the two fluoride groups was not. A large amount of fluoride was deposited in the dentin lesions. In the surface layer, the concentration was increased from 1000 ppm F to more than 2300 ppm F by both fluoride treatments. The concentration of fluoride in both groups of fluoride-treated lesions further increased to more than 3500 ppm F in the approximate center of the lesion before declining in deeper layers toward the level found in the placebo-treated group. The findings from both mineral change and fluoride uptake phases of this study show that in the presence of 90 ppm F, 1% pyrophosphate did not promote demineralization of artificial caries lesions.

Preparation and Measurement of Artificial Enamel Lesions, a Four-Laboratory Ring Test

“…Using single sections, which are measured longitudinally with repositioning, the lesion at the original assessment site (as outlined above), the effect of intra-lesion variation can be minimised [Stephen et al, 1992;Exterkate et al, 1994]. Others have used multiple sec tions per panellist which are analysed individually and then averaged to generate the panellist's average response to a treatment [Mellberg et al, 1988;Stephen et al, 1992],…”

Evaluation of the Effects of a Pyrophosphate-Fluoride Anticalculus Dentifrice on Remineralization and Fluoride Uptake in situ

“…The thin-section sandwich method, which has been described in detail in several previous publications [Mellberg et al, 1986[Mellberg et al, , 1988, was used. Thin sections of polyacrylate-embedded sound enamel, approximately 100 pm thick, were secured with cyanoacrylate adhesive between two thin pieces of polyester plastic for support and to prevent mineral exchange from occurring on the cut faces of the section.…”

“…Because pyrophos phate functions to inhibit calculus formation by inter fering with the formation and growth of crystal nuclei in plaque [McGaughey, 1983], it has the potential of interfering with the natural anticaries mechanism of remineralization. Previous studies, however, have shown that 3.3% pyrophosphate in fluoride dentifrice formulations does not interfere with remineralization in situ [Mellberg et al, 1987] nor does 1% pyrophos phate in a mouthrinse [Mellberg et al, 1988]. Sim ilarly, pyrophosphate did not adversely affect the an ticaries effect of fluoride in a rat caries model [Spak et al, 1988].…”

Relationship of Original Mineral Loss in Caries-Like Lesions to Mineral Changes in situ (Short Communication)

“…It is evident that fluoride is very effec tive in preventing demineralization in all but very shallow lesions and that in situ experimental use of shallow lesions may result in net demineralization, even when a fluoride treatment is given. Subsequent examination of the baseline lesion size in two previ ously reported studies [Mellberg et al, 1988;Deutch- It is also apparent that selection of a relatively nar row range of baseline lesion size should result in re duced variation, and furthermore, if the range is near er the shallow than the deep range, the difference be tween treatments should be greater and, therefore, easier to detect. If large lesions are used, the differ ence between placebo and positive control or test products might be very small, unless, perhaps, a con siderably longer treatment period was used.…”