PERIODONTITIS AND SYSTEMIC DISEASE: BIDIRECTIONAL PATHOGENIC MECHANISMS, DIAGNOSTIC CLASSIFICATION, AND EVIDENCE-BASED PERIODONTAL THERAPY

Background: Periodontitis is a chronic multifactorial inflammatory disease of the supporting structures of the teeth, affecting approximately 45% of adults worldwide and constituting the sixth most prevalent disease globally. Beyond its oral consequences—progressive alveolar bone destruction and tooth loss—periodontitis is now recognized as a bidirectional risk factor for type 2 diabetes, cardiovascular disease, adverse pregnancy outcomes, and rheumatoid arthritis through shared inflammatory mediators and oral-systemic bacteremia pathways. Objective: To review the pathogenic mechanisms linking periodontitis to systemic diseases, the 2018 EFP/AAP diagnostic classification, evidence-based non-surgical and surgical periodontal therapy outcomes, and contemporary preventive strategies. Methods: A systematic review of eight primary sources—including pivotal clinical trials, meta-analyses, and authoritative classification guidelines—published between 2004 and 2024 was conducted. Results: Periodontal treatment reduces HbA1c by a mean of 0.36–0.53% in T2DM patients and lowers circulating CRP by 0.50 mg/L. Step 1 non-surgical periodontal therapy (supra- and subgingival debridement) achieves mean probing depth reduction of 1.5 mm in moderate periodontitis; systemic adjunctive antibiotics (amoxicillin + metronidazole) provide an additional 0.4 mm reduction in severe disease. Supportive periodontal therapy every 3–4 months reduces recurrence rates by 60–70%. Conclusion: Periodontitis is a common, preventable, and treatable chronic inflammatory disease with clinically significant bidirectional links to major systemic conditions. Evidence-based step-wise periodontal therapy combined with long-term supportive care achieves durable disease control and contributes to improved systemic health outcomes.