title: Permanent and transient changes in the reflectance of CO2 laser-irradiated dental hard tissues at lambda = 9.3, 9.6, 10.3, and 10.6 microns and at fluences of 1-20 J/cm2.
abstract: OBJECTIVE
  Effective use of lasers for preventive dental treatments requires accurate knowledge of the amount and distribution of laser energy deposited during irradiation. At CO2 wavelengths, the reflection losses are considerable and reduce the laser energy absorbed by the tissue surface.
  
  
  METHODS
  The specular and diffuse reflectance of enamel and dentin were measured at the 10.6-, 10.3-, 9.6-, and 9.3-microns wavelengths of the CO2 laser. Changes in reflectance during and after laser irradiation were investigated.
  
  
  RESULTS
  The low-fluence reflectance (< 1 J/cm2) of calcified dental tissues at CO2 wavelengths varies between 9% and 50%. Permanent and transient changes in the reflectance are induced at higher irradiation intensities.
  
  
  CONCLUSIONS
  These changes resulted in increased energy coupling during irradiation.
authors.affiliation: University of California, San Francisco 94143-0758, USA.
authors.forename: D
authors.initials: D
authors.lastname: Fried
authors.forename: R E
authors.initials: RE
authors.lastname: Glena
authors.forename: J D
authors.initials: JD
authors.lastname: Featherstone
authors.forename: W
authors.initials: W
authors.lastname: Seka
mesh_terms: D000818:Animals; D002417:Cattle; D003743:Dental Enamel / Q000528:radiation effects*; D003775:Dental Polishing; D003804:Dentin / Q000528:radiation effects*; D006801:Humans; D066298:In Vitro Techniques; D007834:Lasers; D055095:Optics and Photonics; D011829:Radiation Dosage; D013499:Surface Properties