Abstract
CONTEXT: Oval-shaped canals represent a challenge in endodontics. Infected tissue may remain in their recesses. This concern may be more critical with minimally instrumentation techniques. AIMS: The present study evaluated the disinfection ability in oval-shaped canals of a noninstrumentation technique using ultrasonic agitation and intracanal heating of sodium hypochlorite (NaOCl) compared to rotary canal preparation and ultrasonic agitation with and without heating of NaOCl. SETTINGS AND DESIGNS: Sixty extracted mandibular incisors were included. The teeth had pulp necrosis and apical periodontitis and oval-shaped canals. They were divided into three groups depending on the treatment protocol: (1) IHAN: intracanal heating and ultrasonic agitation of NaOCl only, (2) R-IHAN: Rotary preparation followed by IHAN, and (3) R-passive ultrasonic agitation (PUA): Rotary preparation and ultrasonic agitation of NaOCl. METHODS: Root canal samples were taken before (S1) and after (S2) the endodontic procedures were completed and cultured anaerobically. STATISTICAL ANALYSIS USED: Wilcoxon tests were performed to compare colony-forming units (CFUs) before and after the endodontic procedures for the three groups. The percentage of variation of CFUs was compared among the three groups using Kruskal-Wallis tests, followed by Mann-Whitney U-tests. RESULTS: All S1 samples were positive. All S2 samples showed bacterial growth in R-PUA compared to 17 in R-IHAN. None of the S2 samples in IHAN were positive. Bacteria reduction was significant in each group (P < 0.001). The percentage of bacteria reduction was highest for IHAN and lowest for R-PUA (P < 0.001). CONCLUSIONS: Intracanal heating and ultrasonic agitation of NaOCl without instrumentation completely eliminated bacteria from infected oval-shaped canals.