title: Effects of Thermal and Mechanical Load Cycling on the Dentin Microtensile Bond Strength of Single Bond-2.
abstract: BACKGROUND
  Different studies have shown the uncertain effects of thermal cycling (TC) and mechanical load cycling (MC) on the dentin microtensile bond strength (µTBS) of composites. This study designed to investigate the effects of TC and MC on the dentin µTBS of single bond-2.
  
  
  METHODS
  Flat dentinal surface was prepared on 48 sound extracted human third molar teeth, and were bonded by single bond-2 adhesive and Z250 resin composite. The teeth were randomly divided into eight equal groups, according to the thermal/mechanical protocol. TC and MC were proceeded at 5-55°C and 90 N with 0.5 Hz. Then restorations were sectioned to shape the hour-glass form and subjected to µTBS testing at a speed of 0.5 mm/min. To evaluate the bonding failure, the specimens were observed under the scanning electron microscope. The results were statistically analyzed with analysis of variance, t-test, Tukey HSD and post-hoc by using SPSS software version 17 at a significant level of 0.05.
  
  
  RESULTS
  µTBS of all groups were significantly lower than the control group (P < 0.001). Adhesive failure was predominant in all groups and increased with TC and MC.
  
  
  CONCLUSIONS
  TC and MC had an adverse effect on µTBS of the tested adhesive resin to dentin.
authors.affiliation: Associate Professor, Social Determinant of Oral Health Research Center and Department of Operative Dentistry, School of Dentistry, Shahid Sadoughi University of Medical Sciences, Yazd, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Daneshkazemi
authors.affiliation: Professor, Social Determinant of Oral Health Research Center and Department of Operative Dentistry, School of Dentistry, Shahid Sadoughi University Medical Sciences, Yazd, Iran.
authors.forename: Abdolrahim
authors.initials: A
authors.lastname: Davari
authors.affiliation: Graduated Dentist, Shahid Sadoughi University Medical Sciences, Yazd, Iran.
authors.forename: Mohammad Javad
authors.initials: MJ
authors.lastname: Akbari
authors.affiliation: Dentistry Student, Dental Students Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Amin
authors.initials: A
authors.lastname: Davoudi
authors.affiliation: Post-graguate Student, Department of Operative Dentistry, School of Dentistry, Shahid Sadoughi University Medical Sciences, Yazd, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Badrian
keywords: Dentin bonding; mechanical cycling; microtensile bond strength; thermal cycling