Objective: To evaluate the clinical outcomes 2 years after the adjunctive use of an InGaAsP diode and Er,Cr:YSGG laser for nonsurgical treatment of severe periodontitis. Method and materials: Forty-two patients (45.31 ± 9.78 years old, n = 22 females, n = 23 smokers) with stage III or IV grade B periodontitis were randomly treated either with laser (InGaAsP + Er,Cr:YSGG) adjunctive to subgingival debridement (test group, n = 21) or with subgingival debridement alone (control group, n = 21). Subjects in the test group received a second laser treatment in residual sites 2 months after the initial laser therapy. At baseline, and at 12 and 24 months after therapy, periodontal clinical parameters were evaluated. The primary outcome variable was the number of residual deep sites at 12 months (probing depth [PD] ≥ 6 mm). Results: One and two years after nonsurgical periodontal treatment, both groups yielded statistically significant clinical improvements. The adjunctive use of InGaAsP and Er,Cr:YSGG laser to mechanical debridement resulted in statistically significantly higher clinical (PD, clinical attachment level, bleeding on probing, number of sites with PD ≥ 5 mm, PD ≥ 6 mm, PD ≥ 7 mm) improvements (P < .05) compared to subgingival debridement alone both at 12 and 24 months after therapy. Conclusion: In patients with stage III or IV grade B periodontitis, InGaAsP and Er,Cr:YSGG used adjunctively to subgingival debridement may additionally improve the clinical outcomes compared to mechanical debridement alone over a period of 24 months. Keywords: YSGG, InGaAsP, periodontal laser therapy, periodontal treatment, periodontitis

Objective: To evaluate clinically and microbiologically the outcomes following the combined application of InGaAsP diode laser and Er,Cr:YSGG laser for nonsurgical treatment of chronic periodontitis (ChP). Method and materials: Forty-two patients (age 45.31 ± 9.78 years, 22 female, 23 smokers) with ChP were randomly treated with subgingival debridement (SD) by means of ultrasonic and hand instruments (control group, n = 21) or with InGaAsP followed 1 week later by InGaAsP + SD + Er,Cr:YSGG (test group, n = 21). In the test group, a second laser treatment was performed for all residual sites (bleeding sites with probing depth [PD] ≥ 4 mm) 2 months after the first laser therapy. At baseline and 6 months after therapy, periodontal clinical and microbiologic parameters were evaluated. Results: Six months after therapy, statistically significant clinical and microbiologic improvements (PD reduction, clinical attachment level [CAL] gain, quantitative reduction of periopathogens) were observed in both groups compared to baseline. However, the use of InGaAsP followed by SD and the adjunctive use of an Er,Cr:YSGG laser, yielded statistically significantly higher clinical (PD, CAL, bleeding on probing, number of sites with PD ≥ 5 mm, PD ≥ 6 mm, PD ≥ 7 mm) and microbiologic (Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Prevotella intermedia, Peptostreptococcus micros, Fusobacterium nucleatum) improvements (P .05) compared to SD alone. Conclusions: In patients with ChP, the adjunctive use of InGaAsP and Er,Cr:YSGG to SD may additionally improve the clinical and microbiologic parameters obtained with SD alone, thus representing a valuable approach in nonsurgical periodontal therapy. Keywords: chronic periodontitis, diode laser, Er, Cr:YSGG, InGaAsP, laser treatment, nonsurgical periodontal therapy