[Experimental research on preparation of small root canals with EDTA and cirtric acid]

OBJECTIVE:To study the effects of EDTA and citric acid on small root canals so as to provide experimental basis for clinical applications.METHODS:17% EDTA and 50% citric acid are applied to Group A and Group B respectively for three days, each group having 14 extracted teeth with small root canals. The data obtained during the three days' experiment are analyzed with statistic method.RESULTS:The 14 small root canals applied with 17% EDTA solution for three days are all effective, the overall effectiveness rate being 100% and 11 small root canals show an expansion level of 4mm or over, 9 of which reachthe length required for treatment, 11 out of the 14 small root canals applied with 50% citric acid solution for three days are effective (three are not effective), the overall effectiveness rate being 78.57%. 8 small root canals show an expansion level of over 4 mm and all of them reach the length required for treatment.Based upon statistic treatment, the expansion level of small root canals of both Group A and Group B has an obvious difference (P<0.01) after the application.CONCLUSION:EDTA should be the recommended medicine for chemical preparation of small root canals.