Assessment of the Effect of CO2 Laser Irradiation on the Reduction of Bacteria Seeded on Commercially Available Sandblasted Acid-Etched Titanium Dental Implants: An In Vitro Study

Purpose: To evaluate the capability of carbon dioxide (CO2) laser in reducing Escherichia coli on sandblasted acidetched (SAE) titanium dental implants. Materials and Methods: SAE dental implants were contaminated with E coli, incubated in a sterile bacterial culture medium for 24 hours, and then exposed to CO2 laser (10,600-nm wavelength) in superpulsed waves (SPW) at 1.5, 1.7, and 2 W at 100-Hz frequency and continuous wave (CW) at 1.5, 2, and 2.5 W. The presence of bacteria trapped in the implant surfaces after contamination and decontamination was verified using spectrophotometry. Scanning electron microscopy (SEM) was used to evaluate the topography of laser irradiation. After implant surface contamination was verified, implants were exposed to CO2 laser irradiation, and bacterial growth was measured with spectrophotometry. Results: The control implants showed the highest bacterial growth (100% growth). Implants exposed to laser showed progressive increase in the percentage of decontamination (DC%) corresponding to the higher wattage in the SPW and CW groups. The DC% were 20.4%, 49.6%, and 51.7% in the SPW group at 100 Hz, at 1.5, 1.7, and 2 W of power, respectively. In the CW group, the DC% were 34.3%, 69.9%, and 85.5% at 1.7, 2, and 2.5 W, respectively. Kruskal-Wallis statistical analysis showed a significant difference between the groups (P .05). In the pulsed mode (100-Hz) group, statistical analysis showed that the DC% of 1.5 W was significantly lower than the 2 W power. In the CW group, statistical analysis showed that the DC% at 1.7 W was significantly lower (P .05) than with the other treatments. SEM assessment showed craterlike wear damages and accretions to the implant surfaces that increased progressively as the laser wattage increased. Conclusion: CO2 laser irradiation failed to completely decontaminate the implant surfaces. SEM analysis demonstrated damage to the top of the dental implant threads at all settings studied. Thus, CO2 laser irradiation may not be the optimal method to decontaminate implants. Keywords: CO2 laser, decontamination, sandblasted acid-etched implants, scanning electron microscopy