Abstract: Abstract: Objective To evaluate the antimicrobial effect and the clinical curative effects of active silver ion antibacterial solution in treatment of periapical periodontitis in permanent teeth. Methods 80 patients of apical periodontitis were randomly divided into 2 groups with 40 for each group.The samples were instrumented with Mtwo,and then irrigated respectively as following:（group A） syringe irrigation with hydrogen peroxide and physiological saline alternately after root canal preparation （group B）syringe irrigation with hydrogen peroxide and active silver ion antibacterial solution alternately. Bacterial culture was taken before and after the treatment, while the curative effect evaluation was carried out 6 months later. Results A significant decrease in the number of CFUs was observed after treatment in all the groups. Additionally, group B had a significantly higher antimicrobial efficacy as measured by the number of CFUs than group A (P <0.05). In the review half a year later，there was no significant difference between the two groups in efficiency ( P >0.05). Conclusions Active silver ion antibacterial solution is a better choice for clinical root canal irrigation.Combining it with 3% hydrogen peroxide solution is much more effective in eliminating bacterial in the infected root canal, which can improve the clinical result. Its long-term efficacy still needs further research．

Key words: Key words :apical periodontitis, active silver ion antibacterial solution