Root canal treatment (RCT) is a standard procedure for managing pulpal and periapical diseases, but the optimal number of treatment visits remains debated. This study aims to compare the clinical outcomes of single-visit versus multiple-visit RCT in terms of post operative pain, healing of periapical lesions, and treatment success. A randomized controlled trial was conducted with 200 patients diagnosed with irreversible pulpitis or necrotic pulps with periapical involvement, divided into two groups: Group 1 (single-visit RCT) and Group 2 (multiple-visit RCT). Post-operative pain was assessed using a Visual Analog Scale (VAS) at 6, 12, 24, and 48 hours. Healing outcomes were evaluated using radiographic analysis at 3, 6, and 12 months. Results showed that single-visit RCT was associated with significantly higher post-operative pain at 6 and 12 hours (p < 0.05), but no significant difference in pain levels at 24 and 48 hours (p > 0.05). Radiographic healing outcomes at 12 months showed no statistically significant difference between the two groups (p > 0.05). These findings suggest that while single-visit RCT results in higher early post-operative pain, long-term healing and treatment success rates are comparable to multiple-visit RCT. This study highlights the need for case-based selection in determining the appropriate treatment approach.