ABSTRACT
Objective To compare the treatment effect of calcium hydroxide and formocresol applied in root canal disinfection after root canal preparation.Methods 283 patients with 388 teeth diagnosed as chronic periapical were selected.Calcium hydroxide and formocresol were applied after opening of pulp chamber,pulp removed and root canal preparation.Calcium hydroxide was piped into the root canal by screw conveyor to fill the root canal in calcium hydroxide group,and formocresol cotton twist was setted in the root canal after dried in formocresol group.Tampons and ZOE were used for temporary closure.Treatment effects in both groups were compared in a week.Results The total effective rate in calcium hydroxide group was 96.39％,while 79.90％ in formocresol group.The total effective rote in calcium hydroxide group was higher than that in formocresol group(x2 =53.792,P ＜ 0.05).Conclusion Calcium hydroxide was safe,periapical tissue irritation and reliable effect was reached.It was worthy of clinical application.