https://www.selleckchem.com/products/Rapamycin.html PURPOSE To explore the effect of sodium fluoride tooth protector combined with pit and fissure sealing to prevent caries in preschool children. METHODS Two hundred preschool children who were treated with pit and fissure closure from January 2014 to September 2014 were selected as subjects. According to random number table method, 100 cases were divided into the combined group and the control group. Children in the control group were treated with pit and fissure sealant for prevention of caries, while children in the combined group were treated with sodium fluoride tooth protector combined with pit and fissure sealant for caries prevention. The incidence of dental caries, proximal caries, mean DMFT, and expulsion rate of the sealants were compared between the two groups at 1 year and 2 years. Data analysis was performed using SPSS 16.0 software package for data analysis. RESULTS At 1 year of follow-up, there was no significant difference in the incidence of dental caries, proximal caries, and mean DMFT between the two groups (P>0.05). The incidence of caries and mean DMFT in the combined group were significantly lower than those in the control group at 2 years of follow-up (P0.05). CONCLUSIONS Sodium fluoride tooth protector combined with pit and fissure sealing has better anti-caries effect than the use of pit and fissure sealant alone in preschool children.PURPOSE To investigate the effect of single low level laser therapy on initial pain during fixed orthodontic treatment. METHODS Sixty patients who underwent fixed orthodontic treatment in our hospital from January 2015 to December 2017 were enrolled.Patients were divided into 2 groups by random number table method, 30 in each group. Patients in the experimental group were treated with a single low level laser therapy ,while patients in the control group were treated with a placebo.The results of the 2 groups were compared in regard to spontaneous pain and chewi