Decision-making in periodontal therapy plays a crucial role in determining treatment outcomes and long-term periodontal stability. Periodontal management generally follows a phased approach, beginning with non- surgical periodontal therapy and progressing to surgical intervention when indicated. Although flap surgery improves access to root surfaces and alveolar bone, it is not required in every clinical situation. The dilemma of whether to perform flap surgery is particularly relevant in cases with moderate to advanced periodontal destruction. This review discusses the rationale, indications, and clinical parameters guiding the choice between flap and non-flap periodontal therapy, while integrating the contemporary P4 Medicine model to promote evidence-based and patient-centered periodontal care.