Intracanal Cryotherapy Reduces Postoperative Pain in Teeth with Symptomatic Apical Periodontitis: A Randomized Multicenter Clinical Trial.

INTRODUCTION: A prospective, multicentered, randomized clinical trial was designed to assess if controlled irrigation with cold saline could result in less incidence and intensity of postoperative pain in patients presenting with pulp necrosis and symptomatic apical periodontitis. METHODS: A total of 210 patients (presenting with necrotic uniradicular teeth with a diagnosis of symptomatic apical periodontitis and a preoperative visual analog scale (VAS) score higher than 7) were randomly allocated in the control or experimental group after the completion of shaping and cleaning procedures. The experimental group received a final irrigation with 20 mL sterile cold (2.5°C) saline solution delivered to the working length with a sterile, cold (2.5°C) Endovac microcannula (Kerr Endo, Orange Country, CA) for 5 minutes. The same protocol was used in the control group with room temperature saline solution. Patients were instructed to record the presence, duration and level of postoperative pain, and analgesic medication intake. A logistic regression was used to compare the incidence of postoperative pain and the need for painkillers between groups. Differences in general pain intensity between groups were analyzed using the ordinal (linear) chi-square test. Postoperative pain after 6, 24, and 72 hours (recorded in a VAS scale) and the need for analgesic medication intake between the 2 groups were assessed using the Mann-Whitney U test. RESULTS: Patients in the control group presented a significantly higher incidence of postoperative pain, intensity, and need for medication intake (P < .05). CONCLUSIONS: Cryotherapy reduced the incidence of postoperative pain and the need for medication intake in patients presenting with a diagnosis of necrotic pulp and symptomatic apical periodontitis.

Effect of Intracanal Cryotherapy on Reducing Root Surface Temperature.

INTRODUCTION: The 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. METHODS: Twenty 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. RESULTS: Although 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)). CONCLUSIONS: Using 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.

Failure of ProFile instruments used with air, high torque control, and low torque control motors.

OBJECTIVE: The purpose of this study was to evaluate the influence of 350-rpm rotational speed on the failure incidence of ProFile nickel-titanium rotary instruments (PRI) when used by an experienced operator in conjunction with different motors. STUDY DESIGN: Extracted human mandibular and maxillary first and second molars demonstrating curvatures greater than 25 degrees were used. PRI sizes 40 to 15 and with 0.06 taper were used in crown-down fashion at 350 rpm. In groups 1 through 4, air, high torque control, low torque control, and very low torque control motors were used, respectively. Each group included 30 canals. One set of PRI was used for each canal. Before each use the PRI set was sterilized by steam autoclave. The canals were enlarged until a size 25 PRI reached the working length. A 2.5 x magnification was used to check for instrument deformation after each passage. The number of deformed and separated instruments was recorded for the various experimental groups. RESULTS: Instrument deformation and separation did not occur in any of the 4 groups. CONCLUSIONS: The results suggested that the use of PRI in conjunction with the different motors by an experienced operator in a crown-down manner at 350 rpm is safe.