Effect of gallium aluminium arsenide diode laser therapy on Porphyromonas gingivalis in chronic periodontitis: a randomized controlled trial

Objectives: The aim of this randomized, controlled trial was to evaluate the effects of 685-nm gallium aluminium arsenide (GaAlAs) diode laser therapy (1.6 J cm(-2)) as an adjunct to scaling and root planing in the treatment of chronic periodontitis. Methods: Thirty-two patients aged 35-60 years old who had chronic periodontitis met the eligibility criteria. They were randomly assigned to two equal groups: scaling and root planing were performed in the SRP group, while scaling, root planing and laser irradiation of periodontal pockets were performed in the SRP + DL group. Subgingival plaque samples were subjected to polymerase chain reaction (PCR) to detect P. gingivalis-colonized sites, and common clinical indices were evaluated before and 2 months after treatment. Clinical examination included gingival index (GI), plaque index (PI), probing depth (PD), clinical attachment level (CAL) and gingival bleeding index (GBI), all of which were recorded. Results: Data from 30 patients [19 women and 11 men; mean age, 48.4 (5.4) years old] were analysed. There were statistically significant improvements in GI, PD, CAL and GBI for the SRP + DL group compared to SRP group but no significant difference in PI between the groups. Additionally, the percentage of P. gingivalis-positive sites in the SRP + DL group decreased from 80% (12/15) to 20% (3/15) after laser irradiation (P < 0.05). No significant changes were noted in the SRP group. Conclusion: GaAlAs diode laser irradiation of diseased periodontal pockets at 685 nm and 1.6 J cm(-2) seemed to be an effective adjuvant to mechanical instrumentation to treat chronic periodontitis.