INTRODUCTION
Tooth enamel is the hardest mineralized tissue in the human body, consisting of the outermost layer of the dental crown.1 Generally, the demineralization and remineralization of enamel maintain a dynamic equilibrium. Attacked by acids or caries, the enamel lesions come to form as a result of the de/remineralization imbalance.2–3 Once the enamel is damaged, whether by cariogenic bacteria, chemical acids, or mechanical stress, clinical treatments are needed to repair the demineralized enamel since it is a non-living tissue and is not able regenerate.1,4 Conventional interventions in clinical practice mainly consist of the usage of topical fluoride and restorative treatment. Nevertheless, repeated application of fluoride is needed to maintain sustained topical concentrations,5 which may increase the incidence of dental and skeletal fluorosis.6 For restorative treatment, the main flaws are the ageing of resin composite resin and the propensity of new caries to form at the margins of restorations if the causes of the disease are not removed.7 In addition, this treatment requires the sacrifice of surrounding healthy tooth tissue.