title: Shear bond strength of bulk-fill and nano-restorative materials to dentin.
abstract: OBJECTIVE
  Bulk-fill composite materials are being developed for preparation depths of up to 4 mm in an effort to simplify and improve the placement of direct composite posterior restorations. The aim of our study was to compare shear-bond strength of bulk-fill and conventional posterior composite resins.
  
  
  METHODS
  In this study, 60 caries free extracted human molars were used and sectioned parallel to occlusal surface to expose midcoronal dentin. The specimens were randomly divided into four groups. Total-etch dentine bonding system (Adper Scotchbond 1XT, 3M ESPE) was applied to dentin surface in all the groups to reduce variability in results. Then, dentine surfaces covered by following materials. Group I: SonicFill Bulk-Fill, Group II: Tetric EvoCeram (TBF), Group III: Herculite XRV Ultra, and Group IV: TBF Bulk-Fill, 2 mm × 3 mm cylindrical restorations were prepared by using application apparatus. Shear bond testing was measured by using a universal testing machine. Kruskal-Wallis and Mann-Whitney U-tests were performed to evaluate the data.
  
  
  RESULTS
  The highest value was observed in Group III (14.42 ± 4.34) and the lowest value was observed in Group IV (11.16 ± 2.76) and there is a statistically significant difference between these groups (P = 0.046). However, there is no statistically significant difference between the values of other groups. In this study, Group III was showed higher strength values.
  
  
  CONCLUSIONS
  There is a need for future studies about long-term bond strength and clinical success of these adhesive and bulk-fill systems.
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, Zirve University, Gaziantep, Turkiye.|Adjunct Lecturer Department of Conservative Dentistry, College of Dentistry, Ishik University, Erbil City, Iraq.
authors.forename: Hakan
authors.initials: H
authors.lastname: Colak
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, Kırıkkale University, Kırıkkale, Turkiye.
authors.forename: Ertugrul
authors.initials: E
authors.lastname: Ercan
authors.affiliation: Department of Restorative Dentistry, Faculty of Dentistry, Kırıkkale University, Kırıkkale, Turkiye.
authors.forename: Mehmet Mustafa
authors.initials: MM
authors.lastname: Hamidi
keywords: Bulk-fill composite; self-etching adhesive; shear bond strength