This single-center, split-mouth, randomized controlled clinical trial aims to evaluate the clinical effectiveness of Minimally Invasive Non-Surgical Therapy (MINST) as an adjunct to conventional non-surgical periodontal therapy in patients with Stage III/IV periodontitis. Twenty-three systemically healthy adults presenting with bilateral molar teeth exhibiting periodontal pockets ≥5 mm with bleeding on probing will be enrolled. In each participant, molar teeth will be randomly allocated to receive either conventional subgingival scaling and root planing (SRP) using ultrasonic instruments alone (control) or conventional SRP followed by MINST using Mini-Five Gracey curettes under magnification loupes (test). Clinical periodontal parameters, including Plaque Index (PI), Gingival Index (GI), Bleeding on Probing (BOP), Probing Pocket Depth (PPD), and Clinical Attachment Level (CAL), will be evaluated at baseline, 3 months, and 6 months after treatment. The study will investigate whether MINST provides superior clinical outcomes compared with conventional non-surgical periodontal therapy.