A novel blue light laser system for surgical applications in dentistry: evaluation of specific laser-tissue interactions in monolayer cultures

The objective of this study was to examine a new blue light diode laser system (445 nm) for dental soft tissue surgery on cellular level. An in vitro cell culture model was established to evaluate the effects of the 445-nm diode laser in comparison to an established infrared diode laser (IR). Monolayer cell cultures were irradiated and wound healing was morphometrically measured. Fluorescence staining was used for proof of potential DNA double-strand breaks as well as cytoskeleton alterations. Cellular live/dead discrimination was performed and temperature development during laser irradiation was measured with a thermographic infrared camera. A characteristic zone formation was detected after irradiation with both wavelengths. Despite a larger wound area after irradiation with 445 nm, due to its higher temperature development, this laser system showed a faster wound healing in comparison to the IR laser. No increase of devitalized cells was documented with higher distances between laser tip and cell layer and thus without thermal interaction. Neither cytoskeleton alteration nor DNA double-strand breaks could be recorded after irradiation in non-contact mode. The blue diode laser system demonstrated an excellent direct thermal coupling to cells and tissues without side effects even by reduced power settings. The blue diode laser seems to be a promising technology for clinical application due to high absorption of blue light without major side effects in adjacent tissues even by reduced power settings.