In vitro Study of Temperature Changes on the Outer Root Surface of Extracted Human Teeth Under Different Parameters of Intracanal Cryotherapy

Abstract Objectives  The aim of the present study is to investigate the temperature changes on the outer root surface of extracted human teeth during irrigation with different volumes of solutions at different temperatures. Materials and Methods  Thirty premolars extracted for orthodontic or periodontal indications were used for the first experiment and 12 for the second experiment. Root canals were instrumented using WaveOne Gold. Thermosensors were attached to the apical 5 mm and to the middle 5 mm of the outer root surface. Control irrigations with 0.9% NaCl, 2.5% NaOCl, and 17% EDTA at room temperature and experimental irrigations at 2.5°C with 0.9% NaCl, 2.5°C with 2.5% NaOCl, and 2.5°C with 17% EDTA were conducted. Results  During the intracanal cryotherapy, a minimum temperature more than 10°C lower than the initial temperature value was reached. There was no significant difference between the lowest temperature values reached in the irrigations carried out with the three irrigation solutions studied. These results indicate that the effect of intracanal cryotherapy can be successfully achieved using all three types of irrigation solutions, i.e., NaOCl, 0.9% NaCl, EDTA. Intracanal cryotherapy needed to last more than 2 minutes to achieve more than 10°C difference with the initial temperature. Conclusions  A total of 5 mL of irrigation solution for 5 min is insufficient to achieve a cryotherapeutic effect. A temperature difference of 10°C between initial and lowest temperatures recorded was reached fastest at a volume of 20 mL.