Immunomodulatory effects of high versus low intensity diode laser as adjunct to non-surgical periodontal therapy in periodontitis

Periodontitis is characterized by a dysregulated inflammatory response mediated by proinflammatory cytokines. This study aimed to compare the immunomodulatory effects of high-intensity (DLT-H) versus low-intensity (DLT-L) diode laser therapy as adjuncts to conventional scaling and root planning (SRP) in patients with periodontitis. Twenty-seven participants contributing 81 non-adjacent periodontal sites were randomly assigned into three treatment groups: SRP alone, SRP + DLT-H, and SRP + DLT-L. Gingival crevicular fluid (GCF) was collected at baseline, 1 month, and 3 months post-treatment to quantify levels of IL-1β, IL-6, IL-8, and TNF-α. All treatment modalities led to significant reductions in pro-inflammatory cytokine levels over time ( p < 0.01). DLT-H produced the most pronounced and sustained decreases, with early and long-term suppression significantly greater than both SRP alone and DLT-L. DLT-L yielded moderate yet consistent reductions across all cytokines, whereas SRP alone demonstrated limited and less durable immunomodulatory effects. Pairwise comparisons highlighted the superior efficacy of DLT-H in both early (baseline to 1 month) and late (1 to 3 months) intervals, particularly for IL-6 and TNF-α. These findings indicate that high-intensity diode laser therapy provides superior and modulatory benefits and may enhance the outcomes of nonsurgical periodontal therapy.