title: Influence of Different Power Outputs of Er:YAG Laser on Shear Bond Strength of a Resin Composite to Feldspathic Porcelain.
abstract: BACKGROUND
  Porcelain may fracture or chip if exposed to any traumas and can be repaired by using a resin composite.
  
  
  OBJECTIVE
  This study was aimed to evaluate the influences of Er:YAG laser on shear bond strength (SBS) of resin composite to feldspathic porcelain.
  
  
  METHODS
  Seventy-two porcelain blocks were divided into six groups (n=12): G1: no treatment (control group); G2: 9% hydrofluoric acid (HF); G3-6 were separately irradiated with Er:YAG laser using four energy parameters: 2W, 100mj (G3); 3W, 150mj (G4); 4W, 200mj (G5) and 5W, 250mj (G6), respectively; and 20 Hz frequency in long-pulse mode. After silane treatment, a resin composite rod was bonded to each of the porcelain block. The SBS was measured following storage and thermocycling. Data were analyzed by one-way ANOVA, Tamhane and Chi-Square tests.
  
  
  RESULTS
  The highest SBS (12.29±3.04 MPa) was obtained with HF (G2). The lowest SBS (2.23±0.60 MPa) was observed in G4, followed by G3 (1.96±0.76 MPa). G6 had a significantly higher SBS (8.00±2.22 MPa) than other laser irradiation groups.
  
  
  CONCLUSIONS
  Although, Er:YAG laser irradiation at 5W, 250mJ/20 Hz was effective in promoting adhesion of resin composite to feldspathic porcelain compared with the control group, it cannot be used as a safe alternative method to HF acid. Laser irradiation with the evaluated parameters in this study does not promote an effective adhesion on porcelain surface to create adequate bond for clinical use.
authors.affiliation: Dept. of Operative Dentistry, School of Dentistry, Rafsanjan University of Medical Sciences, Rafsanjan, Iran.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Sadeghi
authors.affiliation: Dept. of Operative Dentistry, Member of Social Determinants of Oral Health Research Center, Dental School, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Abdolrahim
authors.initials: A
authors.lastname: Davari
authors.affiliation: Postgraduate Student, Polymer Faculty, Tehran University, Tehran, Iran.
authors.forename: Amin
authors.initials: A
authors.lastname: Abolghasami Mahani
authors.affiliation: Dept. of Microbiology, School of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Hakimi
keywords: Er:YAG laser; Hydrofluoric acid; Porcelain repair; Resin composite; Shear bond strength; Surface treatment