Effect of pH on Galla chinensis extract's stability and anti-caries properties in vitro

GCE solutions were unstable under neutral and alkaline conditions. pH did not significantly influence the inhibiting effect of GCE on enamel demineralization. However, GCE was not effective on polymicrobial biofilms at alkaline pH (8.5). To avoid enamel damage due to acidic treatment, GCE solutions should be used at about pH 5.5.