title: Effect of enamel laser irradiation at different pulse settings on shear bond strength of orthodontic brackets.
abstract: OBJECTIVE
  To compare the effect of laser irradiation at two different pulse settings and acid etching on the shear bond strength (SBS) of orthodontic brackets to enamel.
  
  
  METHODS
  Thirty-six premolars were allocated to three groups (n  =  12): (1) 37% phosphoric acid etching, (2) erbium-doped yttrium aluminum garnet (Er:YAG) laser etching with medium-short pulse mode (MSP; 100 µs, 120 mj, 10 Hz, 1.2 W), and (3) Er:YAG laser etching with quantum-square pulse mode (QSP; 120 mj, 10 Hz, 1.2 W). Metallic brackets were bonded with Transbond XT. After photopolymerization, the samples were subjected to 5000 thermal cycles and debonded with a universal testing machine, and the SBS values were recorded. Surface morphology was evaluated with profilometric examination, scanning electron microscopy, and atomic force microscopy. The adhesive remnant index (ARI) was evaluated to assess the remaining adhesive.
  
  
  RESULTS
  The results of SBS testing were analyzed by one-way analysis of variance and Tukey honestly significant diffference tests. The mean SBS values of QSP and MSP laser groups were 11.80 ± 2.7 MPa and 10.10 ± 4.5 MPa, respectively, and the QSP group demonstrated significantly higher SBS (P < .01) than that of the acid-etched group (6.6 ± 2.4 MPa). No significant difference was observed between the SBS values of the two laser groups (P < .05). The difference between the ARI scores of the laser groups and the acid-etched group was statistically significant (P < .05).
  
  
  CONCLUSIONS
  Laser etching at MSP and QSP modes present successful alternatives to acid etching; however, long-term clinical studies are required to verify clinical success.
authors.affiliation: a  Assistant Professor, Department of Orthodontics, Faculty of Dentistry, Bezmialem Vakif University, Istanbul, Turkey.
authors.forename: Serkan
authors.initials: S
authors.lastname: Sağır
authors.forename: Aslıhan
authors.initials: A
authors.lastname: Usumez
authors.forename: Ebru
authors.initials: E
authors.lastname: Ademci
authors.forename: Serdar
authors.initials: S
authors.lastname: Usumez
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D000704:Analysis of Variance; D001641:Bicuspid; D001840:Dental Bonding / Q000379:methods*; D003743:Dental Enamel / Q000528:radiation effects*; D003799:Dental Stress Analysis; D006801:Humans; D053844:Lasers, Solid-State; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D016910:Orthodontic Brackets; D019279:Resin Cements / Q000528:radiation effects*; D033081:Shear Strength; D013499:Surface Properties
chemical_list: D019279:Resin Cements; C477790:Transbond XT