Effect of Different Methods of Heating Sodium Hypochlorite Irrigating Solution on the External Root Surface...

The aim of this study was to examine the temperature changes on the external root surface across coronal, middle, and apical root thirds upon intracanal and extracanal heating of 5.25% NaOCl.

Seventeen mandibular premolar teeth were trimmed to a length of 20 mm and prepared up to the X3 file of the Protaper Next rotary system. To measure temperatures on different thirds of the external root surface, 3 thermocouples were positioned outside the root. Irrigation was performed by heating the irrigation solution with different methods (room temperature, preheated to 50 °C, intracanal heating at 180 °C for 8 seconds). Temperature changes occurring on different root thirds were recorded and subjected to statistical analysis.

Using the irrigation solution, either extracanal or intracanal heated, resulted in a significant increase in root surface temperatures compared to using at room temperature (P < .05). In intracanal heating group, coronal and middle thirds showed significant increase in root surface temperatures compared to apical third (P < .05). However, in extracanal heating and room temperature groups, coronal third showed significant increase in root surface temperatures compared to middle and apical thirds (P < .05). None of the applications caused a temperature change on the root surface exceeding 10 °C.

Heating of irrigation solution, either extracanal or intracanal, can significantly increase the temperature of the external root surface across its different thirds. Temperatures transmitted outside the root were considered safe for periodontal tissues.