Effects of Intracanal Cryotherapy on Endodontic Postoperative Pain

The goal of this clinical trial is to evaluate the effect of cold saline (2.5 degrees Celsius) irrigation on postoperative pain in patients who require root canal treatment in molar teeth because of dead dental pulp and infection around the apex of the root of the involved teeth. This cold saline irrigation will be done after standard irrigation of the canal using a 5.25% sodium hypochlorite solution. The main questions it aims to answer are: * Is there any difference in postoperative pain when final irrigation is performed using a cold saline solution compared to the irrigation using the saline solution at room temperature in patients who require dental root canal treatment of molar teeth? * Because of cold saline irrigation, what type of adverse event/s may result? Participants will be asked to fill out a questionnaire before the start of the root canal treatment and record the preoperative pain using the visual analog scale (VAS). Root canal treatment will be completed in one visit. The standard procedure of root canal treatment will be followed, including irrigation of the canal using 5.25% sodium hypochlorite. As a final irrigation, either cold saline solution or a normal saline solution at room temperature will be used. The participants will be asked to fill out another questionnaire and record the presence, duration, and intensity of postoperative pain, and if painkiller medicine was taken immediately after completion of root canal treatment and at 6 hours, 12 hours, 72 hours, and 1-week intervals. The researcher will compare the effect of the final irrigation of a cold saline solution with that of a normal saline solution at room temperature on postoperative pain.