title: 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.
abstract: OBJECTIVE
  To evaluate the capability of carbon dioxide (CO₂) laser in reducing Escherichia coli on sandblasted acid-etched (SAE) titanium dental implants.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.forename: Cimara Fortes
authors.initials: CF
authors.lastname: Ferreira
authors.forename: Jegdish
authors.initials: J
authors.lastname: Babu
authors.forename: Erica Krohn Jany
authors.initials: EK
authors.lastname: Migliorati
authors.forename: Sydney
authors.initials: S
authors.lastname: Stein
authors.forename: Franklin
authors.initials: F
authors.lastname: Garcia-Godoy
mesh_terms: D002245:Carbon Dioxide; D003470:Culture Media; D003666:Decontamination / Q000379:methods*; D015921:Dental Implants / Q000382:microbiology*; D004867:Equipment Design; D004926:Escherichia coli / Q000302:isolation & purification; D006801:Humans; D066298:In Vitro Techniques; D007834:Lasers; D054020:Lasers, Gas; D008855:Microscopy, Electron, Scanning; D013053:Spectrophotometry; D013499:Surface Properties; D014025:Titanium / Q000528:radiation effects*
chemical_list: D003470:Culture Media; D015921:Dental Implants; D002245:Carbon Dioxide; D014025:Titanium