title: Comparison of push-out bond strength of fiber-reinforced composite resin posts according to cement thickness.
abstract: BACKGROUND
  Post space size and cement thickness can differ because of variations in root canal morphology, such as an oval shape, and because the entire canal space cannot be included in the post space preparation. As a result, increased cement thickness around the post may affect the bond strength between the post and the dentin.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the push-out bond strength of fiber-reinforced composite resin posts to root dentin with cement layers of varying thickness.
  
  
  METHODS
  Thirty human premolars were endodontically treated and restored with fiber-reinforced composite resin posts. Post space was prepared using a drill with a 1.5-mm diameter and diameters of 1.25 mm (small [S] group), 1.375 mm (medium [M] group), and 1.5 mm (large [L] group) were cemented. The specimens were sectioned horizontally into 1-mm-thick slices, and the push-out bond strengths of the apical and coronal fragments were evaluated. Bond strength was compared using analysis of variance and 2-sample t tests (α=.05).
  
  
  RESULTS
  No significant differences were found in the debonding force and push-out bond strength among fiber-reinforced composite posts of different sizes (P>.05). The mean debonding force and standard deviation of the posts were 25.05 ±9.52 N for the S group, 28.17 ±11.38 N for the M group, and 33.78 ±12.47 N for the L group. The corresponding push-out bond strength values were 3.11 ±1.54 MPa, 3.39 ±1.4 MPa, and 4.15 ±1.75 MPa. The differences in debonding force between the apical (26.43 ±10.72 N) and coronal (31.57 ±12.03 N) areas were not significant (P>.05). However, the differences in push-out bond strength between the apical (4.27 ±1.73 MPa) and coronal areas (2.83 ±1.08 MPa) were significant (P<.05).
  
  
  CONCLUSIONS
  The widening of post spaces and, consequently, the increased cement thickness do not significantly affect the bond strength of fiber-reinforced composite resin posts to root dentin.
authors.affiliation: Resident, Department of Conservative Dentistry, Wonju Severance Christian Hospital, Wonju College of Medicine, Yonsei University, Wonju, Republic of Korea.
authors.forename: Jun-Seong
authors.initials: JS
authors.lastname: Park
authors.affiliation: Assistant Professor, Department of Orthodontics, Wonju Severance Christian Hospital, Wonju College of Medicine, Yonsei University, Wonju, Republic of Korea.
authors.forename: Jeong-Sub
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Professor, Department of Conservative Dentistry, Gangnam Severance Hospital, College of Dentistry, Yonsei University, Seoul, Republic of Korea.
authors.forename: Jeong-Won
authors.initials: JW
authors.lastname: Park
authors.affiliation: Professor, Department of Conservative Dentistry, Wonju Severance Christian Hospital, Wonju College of Medicine, Yonsei University, Wonju, Republic of Korea.
authors.forename: Won-Gyun
authors.initials: WG
authors.lastname: Chung
authors.affiliation: Research Professor, Institute of Lifestyle Medicine, Wonju College of Medicine, Yonsei University, Wonju, Republic of Korea.
authors.forename: Eun-Hee
authors.initials: EH
authors.lastname: Choi
authors.affiliation: Associate Professor, Department of Conservative Dentistry, Wonju Severance Christian Hospital, Wonju College of Medicine, Yonsei University, Wonju, Republic of Korea. Electronic address: yoonlee@yonsei.ac.kr.
authors.forename: Yoon
authors.initials: Y
authors.lastname: Lee
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D003799:Dental Stress Analysis; D006801:Humans; D011176:Post and Core Technique; D019279:Resin Cements / Q000737:chemistry*; D012390:Root Canal Therapy
chemical_list: D003188:Composite Resins; D019279:Resin Cements