RESUMO
INTRODUCTION: The purpose of this prospective, randomized clinical study was to compare the results of a nonactivated single-irrigation protocol (NAI) that used only 1% NaOCl with a passive ultrasonic multi-irrigation protocol (PUI) that used 1% NaOCl, 17% ethylenediaminetetraacetic acid, and 2% chlorhexidine in rendering canals bacteria free. In addition, the effect of a second-visit instrumentation after intra-appointment calcium hydroxide (CaOH(2)) was also evaluated in bacterial elimination. METHODS: Fifty patients were recruited with a posterior tooth requiring primary endodontic treatment of apical periodontitis. Standard nonsurgical endodontic therapy was performed on both groups in a 2-visit approach by using calcium hydroxide intracanal medicament. Teeth were randomly treated with the NAI or PUI protocols in the first visit after complete instrumentation. Bacterial cultures were obtained at 4 periods during treatment from the canals: (1) before instrumentation, (2) after irrigation protocol, (3) after CaOH(2) medication, and (4) before obturation. Statistical analysis was performed on data by using the Fisher exact test and multivariate analysis. RESULTS: NAI and PUI rendered canals 80% and 84% bacteria free, respectively, at the end of the first visit. After CaOH(2) medication the total sample (NAI + PUI) had increased to 87% bacteria free, and the second-visit instrumentation resulted in a total of 91% bacteria free. These differences were not significant (P > .05). CONCLUSIONS: There was no statistical difference between irrigation methods. Each protocol resulted in a high frequency of negative cultures. This high frequency of negative cultures obtained in 1 visit is most likely related to an increased volume and depth of irrigation compared with previously reported protocols.
