title: Shear bond strengths to coronal and pulp chamber floor dentin.
abstract: OBJECTIVE
  To evaluate the bond strengths of two different types of resin bonding systems to coronal dentin and dentin of the pulp chamber floor.
  
  
  METHODS
  20 extracted human molars were sectioned into three regions; superficial coronal dentin, deep coronal dentin and floor of pulp chamber dentin. The dentin surface of each region was bonded with Single Bond or Clearfil Liner Bond 2V. A core build-up light-cured resin composite, Clearfil Photocore, was placed and light-cured for 40 seconds. After storage in 37 degrees C water for 24 hours, shear bond strengths were measured using a single plane shear test assembly at a crosshead speed of 2.0 mm/minute. Morphological changes of the conditioned dentin and hybrid layer formation were observed by SEM.
  
  
  RESULTS
  For Single Bond, the bond strengths to superficial dentin were within anticipated bounds (23 MPa), whereas the bond strengths to deep dentin (15 MPa) and floor of pulp chamber dentin (13 MPa) were significantly lower (P < 0.05). For Clearfil Liner Bond 2V, higher bond strengths (approximately 30 MPa) were obtained for each region. The data were analyzed by one- and two-way ANOVA, and Fisher's PLSD (P < 0.05). The appearance of the conditioned dentin varied according to dentin region and conditioner. For Single Bond, thick hybrid layers (3-4 microm) were observed, while thin hybrid layers (less than 0.5 microm) were observed in Clearfil Liner Bond 2V for all regions.
authors.affiliation: Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, Yushima, Tokyo, Japan. akagawa@xg7.so-net.ne.jp
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Akagawa
authors.forename: Toru
authors.initials: T
authors.lastname: Nikaido
authors.forename: Tsunehiko
authors.initials: T
authors.lastname: Takada
authors.forename: Michael F
authors.initials: MF
authors.lastname: Burrow
authors.forename: Junji
authors.initials: J
authors.lastname: Tagami
mesh_terms: D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate; D001840:Dental Bonding; D003786:Dental Pulp Cavity; D003799:Dental Stress Analysis; D003804:Dentin / Q000648:ultrastructure; D003806:Dentin Permeability; D017220:Dentin-Bonding Agents; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates; D008855:Microscopy, Electron, Scanning; D008963:Molar; D019279:Resin Cements; D033081:Shear Strength; D019228:Tooth Crown
chemical_list: C084544:Clearfil Linerbond System; D017220:Dentin-Bonding Agents; D008689:Methacrylates; D019279:Resin Cements; C115612:single bond; D017438:Bisphenol A-Glycidyl Methacrylate