title: The use of a fiber sleeve to improve fracture strength of pulpless teeth with flared root canals.
abstract: OBJECTIVE
  This study aimed to investigate how use of a fiber sleeve may reduce interfacial debonding and improve fracture strength of pulpless teeth with flared root canals.
  
  
  METHODS
  Pulpless premolars with flared root canals were restored either with a fiber-reinforced post (FRP) alone or with an FRP wrapped in a hollow tubular fiber sleeve. A normal root restored with an FRP alone served as a control. The integrity of resin-dentin and resin-fiber interfaces in the restored roots was evaluated by a stereoscopic system after penetrating a dye. Four roots were tested for each experimental group. Fracture resistance in pulpless premolars with flared root canals restored with an FRP alone or with an FRP/sleeve combination were investigated under bonded and non-bonded conditions with static fracture testing (n=8), and stress distribution in these restored premolars were tested by finite element analysis (FEA).
  
  
  RESULTS
  Flared root canals restored with an FRP/sleeve combination demonstrated superior integrity at the cervical resin-dentin interface to root canals with an FRP alone. Premolars with a flared root canal restored with an FRP/sleeve combination showed significantly greater fracture resistance compared with premolars restored with an FRP alone. FEA showed that once interfacial de-bonding extended to the cervical region of the root, stress concentration in the root dentin dramatically increased.
  
  
  CONCLUSIONS
  The FRP/sleeve combination was effective in reducing debonding and, hence, improving the fracture strength of pulpless premolars with flared root canals.
authors.affiliation: Department of Stomatology, Southwest Hospital, The Third Military Medical University, China. Electronic address: xytmmu@gmail.com.
authors.forename: Yu
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, Taiwan, ROC. Electronic address: d97422003@ntu.edu.tw.
authors.forename: Shih-Hao
authors.initials: SH
authors.lastname: Huang
authors.affiliation: Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Japan. Electronic address: y-takeda@dent.osaka-u.ac.jp.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Shinno
authors.affiliation: Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Japan. Electronic address: yfuruya@dent.osaka-u.ac.jp.
authors.forename: Yu
authors.initials: Y
authors.lastname: Furuya
authors.affiliation: Department of Biomaterials Science, Osaka University Graduate School of Dentistry, Japan. Electronic address: imazato@dent.osaka-u.ac.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Imazato
authors.affiliation: Minnesota Dental Research Center for Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, USA. Electronic address: alexfok@umn.edu.
authors.forename: Alex
authors.initials: A
authors.lastname: Fok
authors.affiliation: Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Japan. Electronic address: mikarin@dent.osaka-u.ac.jp.
authors.forename: Mikako
authors.initials: M
authors.lastname: Hayashi
mesh_terms: D001641:Bicuspid; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D020342:Finite Element Analysis; D006801:Humans; D066298:In Vitro Techniques; D011176:Post and Core Technique; D019279:Resin Cements; D018915:Root Canal Preparation / Q000379:methods*; D014082:Tooth Fractures / Q000517:prevention & control*; D014092:Tooth Root / Q000033:anatomy & histology*; D019553:Tooth, Nonvital
chemical_list: D019279:Resin Cements
keywords: Dentin bonding; Fiber post; Finite element analysis; Flared root canal; Fracture strength; Root fracture; Stress distribution