Effect of Intracanal Cryotherapy on Reducing Root Surface Temperature

• Cryotherapy means lowering or decreasing the temperature of tissues for therapeutic purposes.
• A new methodology to reduce and maintain the external root surface temperature by irrigation is proposed.
• Negative pressure irrigation was used to deliver cold irrigant to the apical third of the prepared root canals in vitro.
• When maintaining a −10°C temperature reduction over 4 minutes, the teeth irrigated by cold saline solution in the experimental group sustained significantly better results than the control group.
• The external reduction of root temperature may have an anti-inflammatory effect on the periradicular tissues.

IntroductionThe positive effect of cryotherapy has been widely described in medicine. The aim of the present study was to validate a new methodology to reduce and maintain external root surface temperature for at least 4 minutes.MethodsTwenty extracted single-rooted teeth were instrumented to size 35/.06 and subjected to 2 different irrigation interventions with a repeated-measures design using 5% sodium hypochlorite first (control) and 2.5°C cold saline solution later (experimental). In both, 20 mL of the irrigant solution was delivered for a total time of 5 minutes with a microcannula attached to the EndoVac system (Kerr Endo, Orange County, CA) inserted to the working length. The initial and lowest temperatures were recorded in the apical 4 mm with a digital thermometer for both irrigants. Data were analyzed with the repeated measure analysis of variance (Greenhouse-Geisser correction) and Bonferroni post hoc tests. Differences in maintaining a −10°C temperature reduction over 4 minutes were assessed with the Fisher exact test.ResultsAlthough significant differences were found between the initial and lowest temperatures in both the control and experimental irrigation procedures (P < .001), the experimental intervention reduced it almost 10 times that of the control. When maintaining a −10°C temperature reduction over 4 minutes, the teeth in the experimental group also sustained significantly better results (P = 3.047 × 10−10).ConclusionsUsing cold saline solution as the final irrigant reduced the external root surface temperature more than 10°C and maintained it for 4 minutes, which may be enough to produce a local anti-inflammatory effect in the periradicular tissues.