Abstract Introduction: Glycine powder air polishing (GPAP) has emerged as a less invasive option for periodontal maintenance therapy. This study aims at comparing the efficacy of GPAP in removing plaque and stains as compared to conventional ultrasonic scaling (USS). Materials and Methods: The present split-mouth randomised clinical trial recruited 20 adults with healthy gingiva or mild gingivitis. Removal of plaque and stains was performed by USS in one maxillary quadrant and by GPAP in the other. Clinical parameters assessed included stain scores by Lobene Stain Index, plaque level by Silness-Loe plaque Index, and pain scores using the Visual Analog Scale. The assessments were performed before and after the treatment and at a 15-day follow-up visit. Results: Significantly lower (P < 0.05) levels of plaque and stains were achieved by both interventions as compared to those before the treatment. While immediate postoperative plaque levels were significantly (P < 0.05) lower following USS, the difference failed to reach statistical significance (P > 0.05) 1 week after the treatment. On the contrary, the stain scores were significantly lower after treatment and at the 7th-day follow-up after GPAP as compared to USS. A significantly greater number of patients (P < 0.05) reported pain to be absent or only mild following GPAP, while those treated with USS experienced pain of severe intensity. Conclusion: Both GPAP and USS are effective in stain and plaque removal. However, GPAP achieved superior stain removal outcomes and was associated with significantly lower pain scores, suggesting it was more comfortable for patients compared to USS.