title: Comparative evaluation of shear bond strength of composite resin bonded to acid etched or Nd:Yag lased enamel.
abstract: OBJECTIVE
  In vitro evaluation of the shear bond strength of composite resin bonded to enamel which is pretreated using acid etchant or pulsed Nd:YAG. Qualitative morphological changes in enamel surfaces were observed under a scanning electron microscope (SEM).
  
  
  METHODS
  60 extracted human teeth were divided in two groups of 30 each (Groups A and B). In Group A, prepared surface of enamel was etched using 35% phosphoric acid (Scotchbond, 3M). In Group B, enamel was surface treated by a surgical Nd:YAG laser beam (Medilas 4060 Fibertom) at 0.8 W, 10 Hz, for 10 s with 80 mJ/pulse power. Bonding agent (single bond dental adhesive, 3M) was applied over the test areas on 20 samples of Groups A and B each, and light cured. Composite resin (Z 100, 3M) was applied onto the test areas as a 3 mm diameter cylinder, and light cured. The samples were tested for shear bond strength. Remaining 10 samples from each group were observed under SEM for morphological changes.
  
  
  RESULTS
  The mean shear bond strength was 20.00 MPa (± 1.93) and 13.28 MPa (±1.97) for Group A and B, respectively. The difference in mean values was statistically significant between Groups A and B (P<0.001). Under SEM, Group A showed typical honeycomb appearance and Group B showed bubble-like cavities.
  
  
  CONCLUSIONS
  In enamel, acid etch technique showed higher shear bond strength.
authors.affiliation: Department of Pediatric Dentistry, Govt. Dental College and Hospital, Mumbai, India. mm_goswami@yahoo.com
authors.forename: Mridula
authors.initials: M
authors.lastname: Goswami
authors.forename: Asha
authors.initials: A
authors.lastname: Singh
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods*; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry*; D001840:Dental Bonding; D003743:Dental Enamel / Q000528:radiation effects / Q000648:ultrastructure*; D045662:Dental Etching / Q000295:instrumentation / Q000379:methods*; D003764:Dental Materials / Q000737:chemistry*; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D053844:Lasers, Solid-State; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010756:Phosphoric Acids / Q000737:chemistry; D055668:Photochemical Processes; D011829:Radiation Dosage; D033081:Shear Strength; D012822:Silicon Dioxide / Q000737:chemistry; D013314:Stress, Mechanical; D013997:Time Factors; D014867:Water / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry
chemical_list: D003188:Composite Resins; D003764:Dental Materials; D010756:Phosphoric Acids; C083568:Z100 composite resin; C115612:single bond; D014867:Water; D017438:Bisphenol A-Glycidyl Methacrylate; D012822:Silicon Dioxide; D015040:Zirconium; C030242:phosphoric acid