Abstract: Objective To evaluate the combined effect of Nd:YAG laser treatment and fluorine varnish on the prevention of redemineralization of dentine caries in deciduous incisors using confocal laser scanning microscope (CLSM). 
Methods Thirty deciduous incisors were collected and randomly divided into three groups, group A (n=10), group B (n=10), and group C (n=10), according to the different treatment methods. Each tooth was divided into mesial and distal parts, which were used as the experimental group and the control group, respectively, in the self-controlled study. Group A received only Nd:YAG laser treatment, including group A1 as the experimental group and group A2 as the control group. Group B was treated with fluorine varnish only, including group B1 as the experimental group and group B2 as the control group, while group C received the combined Nd:YAG laser and fluorine varnish treatment, including group C1 as the experimental group and group C2 as the control group. The artificial superficial dentine caries models were redemineralized after treatment, stained with a solution of fluorescein sodium in ethanol, and ground using grinding plates. The depth of demineralization in longitudinal sections of the teeth was evaluated by CLSM. 
Results The depth of demineralization differed significantly between groups A1 and A2, between groups B1 and B2, and between groups C1 and C2 (P＜0.01). No significant differences in the demineralization depths were found among groups A2, B2, and C2 (P＞0.05). The depth of demineralization differed significantly between groups A1 and C1, and between groups B1 and C1 (P＜0.01), which was smaller in group C1 than in groups A1 and B1 (P＜0.01). 
Conclusion While individual administration of the Nd:YAG laser treatment and fluorine varnish are effective in alleviating the redemineralization of dentine caries in deciduous incisors, the combined treatment is significantly more effective. 

Key words: dental caries, tooth, deciduous, Nd:YAG lasers, fluorine varnish