Studies on a novel combination polymer system: in vitro erosion prevention and promotion of fluoride uptake in human enamel.

Objectives: Firstly, determine the effect of pre-treating sound human enamel with a hydrosoluble combination polymer system (TriHydra™) comprising 0.20% carboxymethylcellulose, 0.010% xanthan gum and 0.75% copovidone, alone or in combination with fluoride, on in vitro erosion by citric acid. Secondly, investigate the effect of the polymers on fluoride uptake by incipient erosive lesions.

Methods: Study 1: Sound enamel specimens were treated (60s, 20°C, 150 rpm) with either (i) deionised water, (ii) polymers in deionised water, (iii) 300 mg/L fluoride or (iv) polymers in 300 mg/L fluoride. Specimen groups (n=5) were then immersed in 1.0% citric acid (pH 3.8, 300 s, 20°C, 50 rpm) and non-contact profilometry was used to determine surface roughness (Sa) and bulk tissue loss. Study 2: Incipient erosive lesions were similarly treated with (i)-(iv). Dynamic Secondary Ion Mass Spectrometry (DSIMS) was then used to determine the fluoride depth-distribution.

Results: Study 1: Mean±SD Sa and erosion depths for treatment groups (i)-(iv) were (a)657±243, (b)358±50, (c)206±72, (d)79±16 nm and (a)19.73±8.70, (b)2.52±1.34, (b)0.49±0.34 and (b)0.31±0.21 mm respectively (matching superscripts denote statistically equivalent groups). Study 2: Lesions treated with (iii) and (iv) exhibited similar fluoride penetration depths (∼ 60 μm). Mean fluoride intensity ratios based on F/(F+P) at 1 μm for treatment groups (i)-(iv) were (a)0.010±0.004, (a)0.011±0.004, (b)0.803±0.148 and (c)0.994±0.004 respectively.

Conclusions: The combination polymer system exhibited anti-erosion efficacy in its own right. The polymer/fluoride admixture statistically significantly reduced Sa, however suppression of bulk tissue loss was not statistically significantly different versus either treatment alone. The presence of polymer appears to promote fluoride uptake by erosive lesions most noticeably in the first 6 μm.