Cellular responses on anodized titanium discs after laser irradiation

Abstract

Although the laser is one of the widely used systems in dental field, literature about the biological effects of laser irradiation on the titanium surface is rare. The aim of this study was to investigate the responses of osteoblast-like cells seeded onto laser irradiated anodized titanium discs, using a CO(2) (carbon dioxide) and Er,Cr:YSGG (erbium chromium-doped yttrium scandium gallium garnet) laser, with reference to cellular proliferation and differentiation in vitro. Osteoblast-like HOS cells were cultured on four differently treated anodized titanium disc surfaces. Group 1, anodized (control); group 2, CO(2) laser irradiated; group 3, Er,Cr:YSGG laser irradiated (150 J/cm(2)); group 4, Er,Cr:YSGG laser irradiated (300 J/cm(2)). MTS-based cell proliferation assay and alkaline phosphatase (ALP) activity test were used to compare cellular responses after 1 and 3 days. Three-way analysis of variance (ANOVA) and post hoc method were carried out to determine the statistical significance of the differences. The cells proliferated actively on all substrates; greatest cellular proliferation was observed in group 4, followed by groups 2, 3, and 1, respectively (P<0.05). The test groups also presented significantly higher ALP activities than the control group (P<0.05) except group 3. For both tests, measured optical densities at 3 days were greater than that of 1 day in control and all test groups (P<0.001). The data shows that irradiation with a CO(2) laser or Er,Cr:YSGG laser may induce a measurable positive effect on osteoblast proliferation and differentiation.