“…Enamel slabs were cut from the sterilised teeth and subsurface lesions were created as previously described [ 29 ]. This involved painting the enamel slabs with acid-resistant nail varnish (Red 745, Revlon, Oxford, NC, USA) to expose two windows (1 × 7 mm) of enamel on each slab that were demineralised for four days at 37 °C using a demineralisation buffer to produce subsurface lesions of approximately 100 μm depth [ 29 ]. The composition of the demineralisation buffer was 80 mL/L Goodrite K-702 polyacrylate (Lubrizol Advanced Materials Inc., Cleveland OH, USA), 500 mg/L hydroxyapatite (Bio-Gel HTP, Bio-Rad Laboratories, Hercules, CA, USA), and 0.1 M lactic acid (Ajax Chemical, Mt Pritchard, NSW, Australia), adjusted to pH 4.8.…”