title: Laser etching of enamel for orthodontic bonding.
abstract: BACKGROUND
  The purposes of this study were to assess the shear bond strength, the surface characteristics, and the adhesive remnant index scores of teeth prepared for bonding with erbium, chromium doped: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser etching, and to compare laser etching with phosphoric-acid etching and a self-etching primer.
  
  
  METHODS
  Sixty-four premolars, extracted for orthodontic purposes, were randomly divided into 4 groups, and a different method was used to prepare the tooth enamel in each group for bonding: irradiation for 15 seconds with a 0.75-W Er,Cr:YSGG laser; irradiation for 15 seconds with a 1.5-W Er,Cr:YSGG laser; etching with 37% phosphoric acid; application of a self-etching primer. After surface preparation, standard edgewise stainless steel premolar brackets were bonded; 1 tooth in each group was not bonded and was examined under a scanning electron microscopic. The brackets were debonded 24 hours later; shear bond strengths were measured, and adhesive remnant index scores were recorded.
  
  
  RESULTS
  Irradiation with the 0.75-W laser produced lower shear bond strengths than the other methods. No statistically significant differences were found between 1.5-W laser irradiation, phosphoric-acid etching, and self-etching primer. Adhesive remnant scores were compared with the chi-square test, and statistically significant differences were found between all groups; when the 0.75-W laser irradiation group was excluded, no statistically significant differences were observed.
  
  
  CONCLUSIONS
  Irradiation with a 1.50-W laser produced sufficient etching for orthodontic bonding, but irradiation with the 0.75-W laser did not.
authors.affiliation: Department of Orthodontics, Faculty of Dentistry, University of Dicle, Diyarbakir, Turkey. torun@dicle.edu.tr
authors.forename: Törün
authors.initials: T
authors.lastname: Ozer
authors.forename: Güvenç
authors.initials: G
authors.lastname: Başaran
authors.forename: Nükhet
authors.initials: N
authors.lastname: Berk
mesh_terms: D000704:Analysis of Variance; D001840:Dental Bonding; D003743:Dental Enamel / Q000528:radiation effects* / Q000648:ultrastructure; D045662:Dental Etching / Q000379:methods*; D003799:Dental Stress Analysis; D006801:Humans; D007834:Lasers; D008963:Molar; D010756:Phosphoric Acids / Q000009:adverse effects; D033081:Shear Strength; D013499:Surface Properties
chemical_list: D010756:Phosphoric Acids; C030242:phosphoric acid