Yu Xiong1, Shih-Hao Huang2, Yuko Shinno3, Yu Furuya4, Satoshi Imazato5, Alex Fok6, Mikako Hayashi7. 1. Department of Stomatology, Southwest Hospital, The Third Military Medical University, China. Electronic address: xytmmu@gmail.com. 2. Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, Taiwan, ROC. Electronic address: d97422003@ntu.edu.tw. 3. Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Japan. Electronic address: y-takeda@dent.osaka-u.ac.jp. 4. Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Japan. Electronic address: yfuruya@dent.osaka-u.ac.jp. 5. Department of Biomaterials Science, Osaka University Graduate School of Dentistry, Japan. Electronic address: imazato@dent.osaka-u.ac.jp. 6. Minnesota Dental Research Center for Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, USA. Electronic address: alexfok@umn.edu. 7. Department of Restorative Dentistry and Endodontology, Osaka University Graduate School of Dentistry, Japan. Electronic address: mikarin@dent.osaka-u.ac.jp.
Abstract
OBJECTIVES: 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. SIGNIFICANCE: The FRP/sleeve combination was effective in reducing debonding and, hence, improving the fracture strength of pulpless premolars with flared root canals.
OBJECTIVES: 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. SIGNIFICANCE: The FRP/sleeve combination was effective in reducing debonding and, hence, improving the fracture strength of pulpless premolars with flared root canals.