Background: Plaque-induced chronic inflammatory gingival enlargement is a reversible consequence of prolonged bacterial plaque accumulation and poor oral hygiene that may impair aesthetics, comfort and masticatory function if untreated. Although its association with plaque is well established, comparative clinical evidence on the effectiveness of routine plaque control in community dental settings, particularly among South Asian populations, remains limited. This study evaluated the effectiveness of structured plaque control measures in reducing plaque-induced chronic inflammatory gingival enlargement. Methods: This prospective quasi-experimental study was conducted by the Department of Dental Public Health, Outpatients Department of Pioneer Dental College and Hospital, Dhaka, Bangladesh, from August 2025 to February 2026. A total of 50 adult outpatients with clinical evidence of plaque-induced chronic inflammatory gingival enlargement were enrolled and followed for twelve weeks after a structured plaque control intervention. Participants received oral hygiene instruction, professional scaling and reinforced brushing guidance and were assessed at baseline and 12 weeks using the Gingival Index, Modified Plaque Index and gingival enlargement score. Data were analyzed using SPSS version 25.0. Results: Following intervention, the mean Gingival Index reduced from 2.14 to 0.68, Modified Plaque Index from 2.31 to 0.72 and gingival enlargement score from 2.85 mm to 1.10 mm, corresponding to reductions of 68.2%, 68.8% and 61.4% respectively (p<0.001 for all). Severe enlargement fell from 42.0% to 4.0%, while participants with no enlargement rose from 4.0% to 36.0%. Improvement was consistent across all oral hygiene habit subgroups. Conclusion: Structured plaque control measures produced substantial and statistically significant improvement in gingival health and enlargement severity within twelve weeks, strongly supporting their integration into routine preventive periodonta