The aim of the study is to evaluate the effectiveness of calcium hydroxide as an intracanal medicament in the clinical and radiographic healing of periapical tissues in teeth diagnosed with symptomatic apical periodontitis. This evaluation will be conducted after multiple visit endodontic treatment. The follow-up sessions will be programmed from 6 to 24 months postoperatively. Postoperative pain will also be considered as a secondary outcome. Participants will be asked to rate their pain level on a numerical scale from 0 to10 before and after each session of endodontic treatment. Additionally, the use of analgesics after the procedure will be measured and the incidence of flare-ups will be evaluated. Two study groups will be formed to undergo multiple-visit endodontic treatment. The intervention group will receive intracanal medication of calcium hydroxide, while the control group will have the root canal left empty between appointments.