An in vitro evaluation of the responses of human osteoblast-like SaOs-2 cells to SLA titanium surfaces irradiated by erbium:yttrium–aluminum–garnet (Er:YAG) lasers

Erbium:yttrium–aluminum–garnet (Er:YAG) laser treatment is an effective option for the removal of bacterial plaques. Many studies have shown that Er:YAG lasers cannot re-establish the biocompatibility of titanium surfaces. The aim of this study was to evaluate the responses of the human osteoblast-like cell line, SaOs-2, to sand-blasted and acid-etched (SLA) titanium surface irradiation using different energy settings of an Er:YAG laser by examining cell viability and morphology. Forty SLA titanium disks were irradiated with an Er:YAG laser at a pulse energy of either 60 or 100 mJ with a pulse frequency of 10 Hz under water irrigation and placed in a 24-well plate. Human osteoblast-like SaOs-2 cells were seeded onto the disks in culture media. Cells were then kept in an incubator with 5 % carbon dioxide at 37 °C. Each experimental group was divided into two smaller groups to evaluate cell morphology by scanning electron microscope and cell viability using 3-4,5-dimethylthiazol 2,5-diphenyltetrazolium bromide test. In both the 60 and the 100 mJ experimental groups, spreading morphologies, with numerous cytoplasmic extensions, were observed prominently. Similarly, a majority of cells in the control group exhibited spreading morphologies with abundant cytoplasmic extensions. There were no significant differences among the laser and control groups. The highest cell viability rate was observed in the 100 mJ laser group. No significant differences were observed between the cell viability rates of the two experimental groups (p = 1.00). In contrast, the control group was characterized by a significantly lower cell viability rate (p < 0.001). Treatments with an Er:YAG laser at a pulse energy of either 60 or 100 mJ do not reduce the biocompatibility of SLA titanium surfaces. In fact, modifying SLA surfaces with Er:YAG lasers improved the biocompatibility of these surfaces.