The Efficacy of Selected Sodium Hypochlorite Heating Methods for Increasing and Maintaining Its Intracanal Temperature—An Ex Vivo Study

Effect of sodium hypochlorite temperature and concentration on the fracture resistance of root dentin

BACKGROUND

Sodium hypochlorite (NaOCl) is the most efficient root canal irrigant to date. The aim of this study was to compare the effect of NaOCl used at different temperatures and concentrations on the compressive strength of root dentin.

MATERIALS AND METHODS

Seventy-two extracted human single-canaled straight roots of comparable size and length were selected and randomly divided into six groups (n = 12): Group (A) served as a control with unprepared canals. The other groups were instrumented with rotary ProTaper Universal files up to size F3. Group (B) was irrigated with 1% NaOCl at room temperature, Group (C) with 1% NaOCl heated to 70 °C, Group (D) with 5.25% NaOCl at room temperature, and Group (E) with 5.25% NaOCl heated to 70 °C. Saline was used in Group (F). The roots were sectioned into 2-mm-thick disks that underwent compression testing using a universal testing machine. Data were analyzed using one-way ANOVA and post hoc Tukey tests. The significance level was set at p ≤ 0.05.

RESULTS

A total of 255 disks were tested. The control group showed the highest compressive strength (p = 0.0112). However, this did not differ significantly from that of heated (p = 0.259) or unheated (p = 0.548) 1% NaOCl. There were no statistically significant differences between the groups of instrumented teeth.

CONCLUSION

Within the conditions of this study, irrigation with NaOCl at different concentrations and temperatures during root canal preparation did not affect the compressive strength of root dentin.

CLINICAL RELEVANCE

This study demonstrates that the use of NaOCl as a root canal irrigant is not associated with a clinically relevant decrease in root compressive strength, especially when compared to saline.

Accuracy of Three Types of Apex Locators versus Digital Periapical Radiography for Working Length Determination in Maxillary Premolars: An In Vitro Study

This study aimed to compare the accuracy of three types of apex locators versus digital radiography for working length (WL) determination. This experimental study was conducted on 58 extracted maxillary premolars. The teeth were decoronated, the access cavity was prepared, and WL was determined using a #15 K-file to serve as reference. The WL was then measured by Woodpex V, Woodpex III, and Root ZX apex locators in the presence of 0.9% saline, and also on a photostimulable phosphor plate (PSP) digital radiograph taken by the parallel technique. The values were compared with the actual WL using the paired t-test (alpha = 0.05). Digital radiography, Root ZX, Woodpex V, and Woodpex III determined the WL within ±0.5 mm from the actual value in 84.48%, 100%, 89.66%, and 87.93% of the cases, respectively. Woodpex V (p = 0.039), Woodpex III (p = 0.001), and Root ZX (p = 0.001) significantly over-estimated the WL. The WL measured on digital radiographs was not significantly different from the actual WL (p = 0.213). The position of the apical foramen (central/lateral) had no significant effect on the accuracy of WL determination by different techniques (p >0.05). Within the limitations of this in vitro study, all the tested modalities showed acceptable accuracy for WL determination in maxillary premolars.