Clinical efficacy of high versus low intensity diode laser as an adjunct to non-surgical periodontal therapy in periodontitis: randomized controlled clinical trial

Scaling and root planing (SRP) is the standard nonsurgical treatment for periodontitis; however, its efficacy in eliminating subgingival biofilm and promoting periodontal healing is often limited, particularly in deep pockets. Adjunctive diode laser therapy has been proposed to enhance clinical outcomes through antimicrobial and host-modulatory effects. This study aimed to evaluate the clinical efficacy of high- and low-intensity diode laser therapy as adjuncts to SRP. A randomized, within-patient, site-level controlled clinical trial was conducted on 27 patients, encompassing 81 periodontal quadrants and 596 sites. Periodontal sites were randomly assigned to three treatment groups: SRP alone as the control, SRP combined with high-intensity diode laser therapy (DLT-H), and SRP combined with low-intensity diode laser therapy (DLT-L). Clinical indices—plaque index (PI), gingival index (GI), probing pocket depth (PPD), and clinical attachment level (CAL)—were assessed at baseline (T0), after one month (T1), and after three months (T2). The results were analyzed using repeated-measures ANOVA followed by post-hoc pairwise comparisons. All three treatment approaches led to statistically significant reductions in PI, GI, PPD, and CAL across the study period (p < 0.001). DLT-H showed greater short-term CAL gains, with significant improvement observed at T1 (p = 0.001 vs. SRP; p = 0.037 vs. DLT-L) and T2 (p < 0.001 vs. SRP; p = 0.018 vs. DLT-L). The DLT-L produced moderate clinical gains, whereas SRP alone yielded early improvements that plateaued over the follow-up period. In contrast, the DLT-H demonstrated consistently superior outcomes compared with both DLT-L and SRP, most notably in clinical attachment level (CAL), indicating more favorable clinical outcomes. Integrating high-intensity diode laser therapy as an adjunct to nonsurgical periodontitis management provides significant short-term clinical benefits, particularly in CAL improvement and inflammation control. In comparison, low-intensity diode laser application offers only moderate advantages, while traditional SRP alone remains effective yet demonstrates minimal periodontal healing capacity. These findings endorse the judicious application of diode laser therapy—especially high-intensity settings—to enhance periodontal outcomes and attachment gain. Long-term studies and further biological assessments and additional biological assessments are warranted to confirm these findings. Trial registration: NCT07013162.