Does acid etching enhance remineralisation of arrested white spot lesions?

Aim: To investigate the effect of acid etching procedure on the remineralisation of white spot lesions (WSL) which had undergone an initial phase of arrest, and to compare between the effect of fluoride and/or CPP-ACP on remineralisation before and after acid etching.
Study Design: In vitro study.
Methods: WSL were prepared in vitro on 130 human enamel slabs which were allocated into four experimental groups (N = 30) and one control group (N = 10). Changes in mineral content were registered weekly by Quantitative Light Induced Fluorescence QLF. When changes had arrested (after 8 weeks), the enamel surface of 20 slabs in each group were acid etched. The remineralisation process was continued until it slowed down again (after 5 weeks).
Results: Mean fluorescence gain was 13.7 ± 0.9% in the fluoride group, 16.5 ± 1.1% in the CPP-ACP group, and 11.4 ± 1.2% in the combination of fluoride and CPP-ACP group.
Conclusions: There was a tendency toward better remineralisation after acid etching but this did not reach a significant level; the effect of etching was more pronounced in the presence of fluoride. Although CPP-ACP seemed to give a steadier rate of remineralisation over time when compared with fluoride, the overall remineralisation in the regimens was similar. In this model, combined treatment of fluoride and CPP-ACP did not have an extra benefit over the fluoride or CPP-ACP alone.