Effects of photodynamic laser and violet-blue led irradiation on Staphylococcus aureus biofilm and Escherichia coli lipopolysaccharide attached to moderately rough titanium surface: in vitro study

This study investigates the in vitro efficacy of photodynamic treatment (PDT) with methylene blue (MB) photoactivated with λ 635 nm diode laser and of λ 405 nm violet-blue LED phototreatment for the reduction of bacterial biofilm and lipopolysaccharide (LPS) adherent to titanium surface mimicking the bone-implant interface.Staphylococcus aureus biofilm grown on titanium discs with a moderately rough surface was subjected to either PDT (0.1% MB and λ 635 nm diode laser) or λ 405 nm LED phototreatment for 1 and 5 min. Bactericidal effect was evaluated by vital staining and residual colony-forming unit count. Biofilm and titanium surface morphology were analyzed by scanning electron microscopy (SEM). In parallel experiments, discs coated wi thEscherichia coli LPS were treated as above before seeding with RAW 264.7 macrophages to quantify LPS-driven inflammatory cell activation by measuring the enhanced generation of nitric oxide (NO). Both PDT and LED phototreatment induced a statistically significant (p <  0.05 or higher) reduction of viable bacteria, up to −99 and −98% (5 min), respectively. Moreover, besides bactericidal effect, PDT and LED phototreatment also inhibited LPS bioactivity, assayed as nitrite formation, up to −42%, thereby blunting host inflammatory response. Non-invasive phot otherapy emerges as an attractive alternative in the treatment of peri-implantitis to reduce bacteria and LPS adherent to titanium implant surface without causing dam...
Source: Lasers in Medical Science - Category: Laser Surgery Source Type: research