Method: Human enamel samples, with artificial WSL created using a two-layer system, were assigned to 4 groups (n=8); a: BAG paste, b: PAA-BAG paste, c: proprietary remineralisation solution and d: de-ionised water as a control. Each surface treatment was applied for 7 days at 37oC and refreshed daily. Mechanical properties were assessed using en face and cross-section Knoop microhardness (50 g for 10 sec). Micro-Raman spectroscopy (streamline mode) was used to scan lesion cross-sections (approx. 1740 spectra in each map). The intensity of Raman hydroxyapatite (HA) phosphate peak (959 cm-1) was measured using in-house software producing depth line-profiles to compare the intensity / lesion depth between the experimental groups. Another 20 samples (n=5) were used to obtain 3D images of lesion surfaces using non-contact white light profilometry permitting measurement of lesion step height in relation to the sound enamel reference level. Data was analysed statistically (P=0.05).
Results: BAG, PAA-BAG and a “standard” remineralisation solution increased statistically significantly the surface and cross-section Knoop microhardness compared to the control (P<0.001). Raman HA phosphate peak intensity in the control group was significantly less than other groups (P=0.01). There was no difference in the lesion depth according to Raman depth profile analysis. The step height measurement exhibited no difference between the experimental groups.
Conclusion: BAG and PAA-BAG may enhance enamel WSL remineralisation as their use improved lesion mechanical properties and increased Raman HA phosphate peak intensity.