Abstract: Objective:To observe the clinical effect of root canal disinfection with calcium hydroxide iodoform paste and compare the role with formaldehyde cresol formocresol. Methods:One hundred and twelve teeth which had the symptoms were chosen to do root canal treatment. These teeth were divided into observation group and control group. The teeth in each group were completed root canal treatment in 2 times. The teeth in observation group were disinfected using calcium hydroxide iodoform paste in root canals,while others in control group were disinfected using formaldehyde cresol formocresol cotton absorbents. The clinical effect was evaluated in the first subsequent consultation a week later. Results:One week after the root canal treatment,the currative effect in observation group was better than the control group(P<0.05). Conclusions:The clinical effect is obvious when root canal was disinfected with calcium hydroxide iodoform paste.