title: Effects of KTP laser irradiation, diode laser, and LED on tooth bleaching: a comparative study.
abstract: OBJECTIVE
  This in vitro study examines the whitening efficacy of a light-emitting diode (LED), a diode laser, and a KTP laser irradiation in dental bleaching by analyzing the change in color achieved from the treatment, the temperature increase induced in the pulpal cavity, as well as enamel microhardness measurement after treatment.
  
  
  BACKGROUND
  Bleaching techniques achieved significant advances with the use of coherent or incoherent radiation sources to activate the bleaching agents.
  
  
  METHODS
  A hydrogen peroxide bleaching agent, Hi-Lite, was stimulated with an LED, a 980-nm diode laser at 0.8 W, or a 532-nm KTP laser at 1.0 W for 30 sec on 64 extracted human incisors. During irradiation, the temperature in the pulpal cavity was monitored. The color change was evaluated using the CIE L*a*b* color space measurement system, and Vikers enamel microhardness was tested after treatment.
  
  
  RESULTS
  A mean total color difference value (DeltaE*) greater than 5.0 was obtained in each group. KTP-laser-induced bleaching gave a significantly higher DeltaL* (8.35) after treatment (p < 0.01). Neither LED nor the two lasers produced significant differences in the enamel microhardness after treatment (p > 0.01). Mean maximal pulpal temperature rise was 2.95 degrees C for LED, 3.76 degrees C for KTP laser, and 7.72 degrees C for diode laser, respectively.
  
  
  CONCLUSIONS
  The results of this study suggest that KTP laser is effective at providing brighter teeth. According to the conditions used in this study, the LED and KTP laser induced a safer pulpal temperature increase when assisted with Hi-Lite bleaching gel.
authors.affiliation: Department of Special Dental Service, School and Hospital of Stomatology, Peking University, Beijing, China.
authors.forename: Chengfei
authors.initials: C
authors.lastname: Zhang
authors.forename: Xiaogu
authors.initials: X
authors.lastname: Wang
authors.forename: Jun-Ichiro
authors.initials: J
authors.lastname: Kinoshita
authors.forename: Baohong
authors.initials: B
authors.lastname: Zhao
authors.forename: Teruo
authors.initials: T
authors.lastname: Toko
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kimura
authors.forename: Koukichi
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D001831:Body Temperature / Q000528:radiation effects; D003782:Dental Pulp / Q000528:radiation effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D066298:In Vitro Techniques; D007834:Lasers; D016877:Oxidants / Q000494:pharmacology; D010789:Phototherapy; D014073:Tooth Bleaching / Q000379:methods*
chemical_list: D016877:Oxidants; D006861:Hydrogen Peroxide