title: Debonding of ceramic brackets by a new scanning laser method.
abstract: BACKGROUND
  The purpose of this in-vitro study was to develop a new method to debond ceramic brackets by scanning with an Er:YAG laser.
  
  
  METHODS
  Sixty bovine mandibular incisors were randomly divided into 2 groups of 30. Polycrystalline ceramic brackets were placed on their labial surfaces by using the orthodontic composite adhesive Transbond XT (3M Unitek, Monrovia, Calif) and light cured for a total of 40 seconds. The first group was the control group, with no laser application performed. The Er:YAG laser was used on each bracket in the study group at 4.2 W for 9 seconds with the scanning method. The force required for debonding the brackets was applied 45 seconds after laser exposure. Shear bond strengths were measured in megapascals with a universal testing machine, and adhesive remnant index scores were assigned to each specimen.
  
  
  RESULTS
  Statistically significant (P <0.001) lower shear bond strengths were found in the laser group (9.52 MPa) compared with the control group (20.75 MPa). Likewise, the adhesive remnant index scores were statistically different (P <0.001); the laser group had twice as many samples with adhesive, with the adhesive remnant index scores of 2 or 3.
  
  
  CONCLUSIONS
  The application of the Er:YAG laser with the scanning method is effective for debonding ceramic brackets by degrading the adhesive through thermal softening.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, Yeditepe University, Istanbul, Turkey.
authors.forename: Mehmet Oguz
authors.initials: MO
authors.lastname: Oztoprak
authors.forename: Didem
authors.initials: D
authors.lastname: Nalbantgil
authors.forename: Ayşe Sine
authors.initials: AS
authors.lastname: Erdem
authors.forename: Murat
authors.initials: M
authors.lastname: Tozlu
authors.forename: Tülin
authors.initials: T
authors.lastname: Arun
mesh_terms: D000818:Animals; D002417:Cattle; D003738:Dental Cements / Q000528:radiation effects*; D017005:Dental Debonding / Q000295:instrumentation* / Q000379:methods; D003743:Dental Enamel / Q000528:radiation effects*; D003776:Dental Porcelain; D053844:Lasers, Solid-State; D016382:Orthodontic Appliance Design; D016910:Orthodontic Brackets; D011897:Random Allocation; D019279:Resin Cements / Q000528:radiation effects*; D033081:Shear Strength
chemical_list: D003738:Dental Cements; D019279:Resin Cements; C477790:Transbond XT; D003776:Dental Porcelain