title: Development of calcium phosphate/sulfate biphasic cement for vital pulp therapy.
abstract: OBJECTIVE
  Bioactive calcium phosphate cement (CPC) has been used widely to repair bone defects because of its excellent biocompatibility and bioactivity. However, the poor handling properties, low initial mechanical strength, and long setting time of CPC limit its application in vital pulp therapy (VPT). The aim of this study was to synthesize biphasic calcium phosphate/sulfate cements and evaluate the feasibility of applying these cements in VPT.
  
  
  METHODS
  The physical, chemical, and mechanical properties of CPC were improved by mixing the cement with various amounts of α-calcium sulfate hemihydrate (CSH). The hydration products and crystalline phases of the materials were characterized using scanning electron microscopy and X-ray diffraction analysis. In addition, the physical properties, such as the setting time, compressive strength, viscosity, and pH were determined. Water-soluble tetrazolium salt-1 and lactase dehydrogenase were used to evaluate cell viability and cytotoxicity.
  
  
  RESULTS
  The developed CPC (CPC/CSH cement), which contains 50wt% CSH cement, exhibited no obvious temperature increase or pH change during setting when it was used as a paste. The initial setting time of the CPC/CSH biphasic cement was substantially shorter than that of CPC, and the initial mechanical strength was 23.7±5.6MPa. The CPC/CSH cement exhibited higher viscosity than CPC and, thus, featured acceptable handling properties. X-ray diffraction analysis revealed that the relative peak intensity for hydroxyapatite increased, and the intensity for calcium sulfate dehydrate decreased as the amount of CPC was increased. The cell viability and cytotoxicity test results indicated that the CPC/CSH cement did not harm dental pulp cells.
  
  
  CONCLUSIONS
  The developed CPC/CSH biphasic cement exhibits substantial potential for application in VPT.
authors.affiliation: Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, No. 1, Chang-De St., Jhong-Jheng District, Taipei City 100, Taiwan, ROC. Electronic address: d96422005@ntu.edu.tw.
authors.forename: Kai-Chun
authors.initials: KC
authors.lastname: Chang
authors.affiliation: Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, No. 1, Chang-De St., Jhong-Jheng District, Taipei City 100, Taiwan, ROC.
authors.forename: Chia-Chieh
authors.initials: CC
authors.lastname: Chang
authors.affiliation: Institute of Materials Science and Engineering, National Taipei University of Technology, No. 1, Sec. 3 Chung-Hsiao E. Rd., Da-an District, Taipei City 106, Taiwan, ROC.
authors.forename: Wei-Tang
authors.initials: WT
authors.lastname: Chen
authors.affiliation: Institute of Materials Science and Engineering, National Taipei University of Technology, No. 1, Sec. 3 Chung-Hsiao E. Rd., Da-an District, Taipei City 106, Taiwan, ROC.
authors.forename: Chung-King
authors.initials: CK
authors.lastname: Hsu
authors.affiliation: Institute of Biomedical Engineering, National Taiwan University, No. 1, Sec. 1, Ren-Ai Rd., Jhong-Jheng District, Taipei City 100, Taiwan, ROC.
authors.forename: Feng-Huei
authors.initials: FH
authors.lastname: Lin
authors.affiliation: Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University, No. 1, Chang-De St., Jhong-Jheng District, Taipei City 100, Taiwan, ROC; National Taiwan University Hospital, National Taiwan University, No. 1, Chang-De St., Taipei City 100, Taiwan, ROC. Electronic address: pinlin@ntu.edu.tw.
authors.forename: Chun-Pin
authors.initials: CP
authors.lastname: Lin
mesh_terms: D002130:Calcium Phosphates / Q000737:chemistry* / Q000633:toxicity; D002133:Calcium Sulfate / Q000737:chemistry* / Q000633:toxicity; D018929:Cell Culture Techniques; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D019245:Compressive Strength; D003461:Crystallography; D003738:Dental Cements / Q000737:chemistry* / Q000633:toxicity; D003782:Dental Pulp / Q000166:cytology / Q000187:drug effects; D005240:Feasibility Studies; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D057872:Pulp Capping and Pulpectomy Agents / Q000737:chemistry* / Q000633:toxicity; D013314:Stress, Mechanical; D013696:Temperature; D013778:Tetrazolium Salts; D013997:Time Factors; D014783:Viscosity; D014961:X-Ray Diffraction
chemical_list: D002130:Calcium Phosphates; D003738:Dental Cements; D007202:Indicators and Reagents; D057872:Pulp Capping and Pulpectomy Agents; D013778:Tetrazolium Salts; C020243:calcium phosphate; D007770:L-Lactate Dehydrogenase; D002133:Calcium Sulfate
keywords: Biphasic cement; Calcium phosphate cement (CPC); Cytotoxicity; Mechanical property; Vital pulp therapy (VPT); α-Calcium sulfate hemihydrate (CSH)