The Influence of Fluoride Varnish on the Attrition of Dentine

Abstract

Previous investigations have shown the potential for fluoride to be protective in an abrasion/erosion laboratory model. The aim of this study was to investigate the effect of high concentrations of fluoride delivered in a varnish on attrition of dentine. Fifteen caries-free, intact lower third molar teeth were sectioned and the enamel removed by a water-cooled diamond disc. Polished dentine surfaces were divided into 8 areas, 4 of which were randomly covered with a high-concentration fluoride varnish for 24 h. The samples were subjected to 5,000 cycles of attrition bathed under artificial saliva. Microhardness testing adjacent to the wear scars showed no statistical difference between the fluoride-treated (71.42 KHN, SD 10.52) and control surfaces (72.66 KHN, SD 9.69). The volume of the wear scar was statistically greater for the fluoride-treated surface at 9.6 µm³ (SD 4.92) and 8.13 µm³ (SD 5.54) for the control areas (p = 0.029). The low pH of the fluoride varnish appears to have increased the amount of wear from attrition in this laboratory study.

An experiment on the attrition of acid demineralized dentine in vitro

“…The enamel from 10 third molar teeth was then carefully removed, exposing the underlying dentine and the sections embedded flush in acrylic blocks following previously published protocols. 4 The exposed dentine section surface was polished progressively with 600 through 2000 grit sandpapers to form a smooth flat surface. Following specimen preparation, the samples were cleaned in an ultrasonic bath for 2 minutes at room temperature and the dentine surfaces arbitrarily divided into 8 equally sized 1 mm 3 zones.…”

“…Subsequently, the tip of a buccal cusp of an intact and unworn premolar tooth was placed vertically in an Enduratec wear machine (TEC ELF Model 3300, Bose, Eden Prairie, MN, USA) and positioned so that it moved against the dentine sections using the protocols described in an earlier study. 4 Each stroke of the Enduratec machine comprised a load of 150 N, a frequency of 10 Hz, stroke length 1 mm. The regime continued for a total of 5000 return strokes with artificial saliva acting as a lubricant.…”

“…The volume measurement was repeated for all 8 scars per dentine sample and then for all 10 sections. 4 The accuracy and reproducibility of the scanner and software have previously been published and had a maximum resolution of ± 1 lm and repeatability of ± 5 lm. Two randomly selected samples were dehydrated and sputter coated with gold for examination with a SEM machine (JSM-5900LV, Jeol Ltd, Tokyo, Japan) at 20 KV.…”

“…1,2 However, the role of attrition, which is wear of tooth against tooth, has been relatively under-investigated because of the difficulty of developing an appropriate laboratory model. 3,4 Fluoride may have a preventive role in the progression of wear caused by abrasion 5 but there is comparatively little data on its effect on attrition. Our recent laboratory study showed that DuraphatÒ varnish (Colgate Ltd, UK) randomly applied to polished dentine sections and subjected to attritional wear from the cusp of an upper premolar caused statistically more tooth wear than controls.…”

“…Our recent laboratory study showed that DuraphatÒ varnish (Colgate Ltd, UK) randomly applied to polished dentine sections and subjected to attritional wear from the cusp of an upper premolar caused statistically more tooth wear than controls. 4 We postulated that the reason for this was the lower pH of the varnish (pH 3.4) or the lubricating effect of the varnish. There was no visible difference in wear between the dentine samples evident on SEM images and similarly, microhardness was not statistically different between the DuraphatÒ varnish treated samples and the control samples.…”