Intracanal heating of sodium hypochlorite: Scanning electron microscope evaluation of root canal walls

Abstract

Introduction:The aim of this study is to evaluate the surface of root canals dentine using scanning electron microscope (SEM) after instrumentation with rotary Nickel-Titanium systems and two different protocols of activation of sodium hypochlorite (NaOCl) (extracanal heating at 50°C and intracanal heating at 180°C), to assess the presence/absence of smear layer and also the presence/absence of open dentinal tubules along the walls at the coronal, middle, and apical third of each sample.Materials and Methods:Thirty-six single-rooted teeth were selected, divided into three groups and shaped with ProTaper Universal instruments following irrigation protocols with 5.25% NaOCl. At the end of the preparation, three different protocols of activation were used: nonheated NaOCl in Group A, extra-canal heated NaOCl at 50°C for Group B and intracanal heated NaOCl at 180°C for Group C. Specimens were cut longitudinally and analyzed by SEM at standard magnification of ×1000. The presence/absence of the smear layer as well as the presence/absence of open tubules at the coronal, middle, and apical third of each canal were estimated using a five-step scale for scores. Numeric data were analyzed using Kruskal–Wallis and Mann–Whitney U statistical tests and significance was predetermined at P < 0.05.Results:Kruskal–Wallis analysis of variance (ANOVA) for debris score showed significant differences among the Ni-Ti systems (P < 0.05). Mann–Whitney test confirmed that Group A presented significantly higher score values than other Ni-Ti systems. The same results were assessed considering the smear layer scores. ANOVA confirmed that the apical third of the canal maintained a higher quantity of debris and smear layer after preparation of all the samples.Discussion and Conclusions:Intra-canal heating of NaOCl at 180°C proved to be more effective in obtaining clean canal walls. On the other hand, extra-canal heating at 50°C of NaOCl left a higher quantity of debris and the smear layer was widely represented.

Capacidad de Disolución del Hipoclorito de Sodio con o sin Activación

“…Al igual que en este estudio, los modelos in vitro a menudo no replican la realidad clínica 15 pero, permiten saber qué tan efectiva es la activación para acelerar los procesos de disolución de tejido, sin considerar otros factores clínicos. Se ha reportado que la activación / agitación del irrigante mejora de manera importante la acción antibacteriana y la acción de disolución de tejidos del NaOCl 16 .…”

Effect of Heated Sodium Hypochlorite on the Viscoelastic Properties of Dentin Evaluated Using Dynamic Mechanical Analysis

“…(https://www.endoruddle.com/blogs/show/15/heating-sodium-hypochlorite-peer-reviewed-evidence-supporting-theheating-of-naocl-, accessed 13/03/2019) and its testing at such temperatures (11) and beyond (17,18), it would be logical to investigate the effect of heated sodium hypochlorite on the viscoelastic properties of dentin under dynamic loading (19). We hypothesized that exposure of dentin bars to heated NaOCl would significantly change their viscoelastic properties.…”

Conservative management of periapical lesions of endodontic origin - a review of the different techniques

“…Irrigating solutions such as NaOCl, citric acid, EDTA, chlorhexidine and others help reduce the microbial flora of the infected canals, and the ultrasonic activation of the irrigants increases their efficiency (38,39). It is proven that ultrasonically activated warm sodium hypochlorite can better dissolve and eliminate necrotic tissue (11,40,41). According to some authors if the endodontic infection is eliminated, the immune system is able to promote lesion repair (21, 42).…”