Ex vivo ability of a noninstrumentation technique to disinfect oval-shaped canals

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.

Conservative shaping combined with three-dimensional cleaning can be a powerful tool: Case series

“…This protocol has been recently shown to result in a significantly better disinfection and cleanliness compared to passive ultrasonic irrigation. [ 11 13 20 21 22 ] The smear layer produced during instrumentation minimizes the penetration of disinfectants into the dentinal tubules and their antibacterial activity in dentin. Irrigation with 17% EDTA removes smear layer blocking dentinal tubules, resulting in cleaner canals and a better penetration of warm NaOCl in the dentinal tubules and lateral anatomies following a conservative canal preparation.…”

“…Irrigation with 17% EDTA removes smear layer blocking dentinal tubules, resulting in cleaner canals and a better penetration of warm NaOCl in the dentinal tubules and lateral anatomies following a conservative canal preparation. [ 11 ] Amato et al . demonstrated that, in canals with a conservative shape (size 30 at the tip and a 4% taper), 3D cleaning was the only irrigation protocol allowing the dissolution of pulp tissue in artificial lateral canals.…”

“…[ 10 ] However, a recent study showed that it was not necessary to touch root canal walls to kill bacteria. [ 11 ] It could be assumed that the sequential action of 17% EDTA and 3D cleaning compensated for the reduced percentage of untouched and noninstrumented root canal walls, resulting in an adequate disinfection. [ 11 ]…”

“…[ 10 ] However, a recent study cast doubt on the importance to touch root canal walls during instrumentation. [ 11 ] Bacteria remained in oval-shaped canals following conventional preparation and passive ultrasonic irrigation. On the other hand, a noninstrumentation protocol based on intracanal heating and ultrasonic agitation of sodium hypochlorite rendered all the canals bacteria free.…”

“…On the other hand, a noninstrumentation protocol based on intracanal heating and ultrasonic agitation of sodium hypochlorite rendered all the canals bacteria free. [ 11 ]…”