Antimicrobial Therapy Using Laser Shock Waves and Hydrogen Peroxide

Porphyromonas gingivalis is an putative periodontal pathogen in the etiology of aggressive periodontitis (AgP). It is generally accepted, that for the therapy of AgP scaling and root planing alone is not the adequate treatment. Either open flap surgery or adjunctive antimicrobial therapy with systemic antibiotics is indicated. In a pilot study it was shown, that laser shock waves or 0.5% hydrogen peroxide alone have no significant bactericidal effect on Porphyromonas gingivalis. However the combination of acoustic laser shock waves, without heat generation, in combination with hydrogen peroxide solution could offer an alternative to the conservative antimicrobial therapy. Objectives: The aim of this in vitro study was to assess the effect of shock waves generated by a Q-switched Nd:YAG laser + 0.5% hydrogen peroxide on the viability of P. gingivalis. Methods: After 4 days of cultivation in liquid Schaedler medium P. gingivalis.was exposed to 0.5% hydrogen peroxide for 15 (28 samples) or 30 minutes (28 samples) or no hydrogen peroxide (16 controls) and immediately thereafter to irradiation by laser light. The irradiation time was 15 and 30 seconds and the energy/pulse was 5, 10 and 15 mJ. After 3 days of cultivation in fresh medium the viability was assessed by measurement of optical density (OD). Results: After an hydrogen peroxide exposure time of 30 minutes and a laser irradiation with an energy density * 13 mJ/cm2 as well as an energy/pulse * 10 mJ the viability of P. gingivalis.was statistically significant reduced from an OD of 0.014 without hydrogen peroxide to an OD of 0.002 with the combined treatment. Conclusions: Based on these data it could be concluded, that acoustic laser shock waves in 0.5% hydrogen peroxide solution could enhance the antimicrobial effect on P. gingivalis. This study was supported by BMBF, Grant No. FKZ 13N6766.