Effect of diode laser irradiation on the survival rate of gingival fibroblast cell cultures.
OBJECTIVE
The present study is part of a basic research program investigating the cellular effects of the GaAlAs-diode laser with a wavelength of 810 nm on human periodontal tissues. The aim of the investigation was to evaluate the effects of the laser treatment on the survival rate of human gingival fibroblasts (HGF) in monolayer cell culture at different power settings and durations.


METHODS
HGF were obtained from a human gingival connective tissue explant. Cells were cultured on 24-well tissue culture plates. One hundred and thirty multi well cell cultures were laser treated. The variable parameters were power output (0.5-2.5 W) and exposure time (60-240 seconds per well). The cultures were analyzed by means of trypan blue staining, and the cell numbers counted under a light microscope. Photographs before and after irradiation were taken and evaluated.


RESULTS
Depending on different settings, the laser irradiation caused significant (P < 0.05, t-test) reductions of cell numbers. Exposure time was more relevant to this phenomenon than the power output. Linear regression analysis revealed no unambiguous correlation between power output and cell death, when exposure time was kept constant.


CONCLUSIONS
When used for periodontal pocket decontamination, the laser beam may cause damage to collateral periodontal tissues, if the power setting and the duration of the treatment are not adequate. Further investigation, especially with regard to the effects on hard tissue and microorganisms, are needed to give a secure recommendation for irradiation parameters at pocket decontamination.
Kreisler
M
M
Department of Oral Surgery, Johannes Gutenberg-University, Mainz, Germany. kreisler@mail.uni-mainz.de
Daubländer
M
M
Willershausen-Zönnchen
B
B
d'Hoedt
B
B
D002452:Cell Count; D002470:Cell Survival; D002478:Cells, Cultured; D005347:Fibroblasts / Q000528:radiation effects*; D005881:Gingiva / Q000528:radiation effects*; D006801:Humans; D007834:Lasers