title: Why Biphasic? Assessment of the Effect on Cell Proliferation and Expression.
abstract: BACKGROUND
  Tricalcium silicate (TCS)-based materials are used in endodontics because they are hydraulic and interact with blood, tissue fluids, and phosphate-based root canal irrigants, resulting in biomineralization. Newer-generation materials are biphasic; calcium phosphate is added to the TCS; thus, the material has 2 cementitious phases. The effect of this addition is not known; thus, the aim of this study was to characterize biphasic cements and assess cellular proliferation and expression.
  
  
  METHODS
  TCS cement mixed with calcium phosphate monobasic or hydroxyapatite in 1:1 proportion was prepared. The powders and the mixed cements soaked in Hank's balanced salt solution for 28 days were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy, and X-ray diffraction analysis. Ion leaching was investigated using inductively coupled plasma mass spectroscopy. Cellular interaction with material leachate was investigated by exposing human primary osteoblasts to the leachate from the cements. Cell growth and proliferation were determined using methyltetrazolium assay and SEM.
  
  
  RESULTS
  The addition of a calcium phosphate phase to tricalcium silicate changed the material hydration with a reduction in pH and calcium ion release in the leachate when calcium phosphate monobasic was added. No crystalline calcium hydroxide was formed for both biphasic materials. The biphasic cements exhibited a reduction in cell growth and proliferation. SEM of the materials showed heavy carbonation of the material surface caused by processing for microscopy.
  
  
  CONCLUSIONS
  The addition of a second cementitious phase results in modification of the hydration characteristics of TCS cement with deterioration of material and biocompatibility properties.
authors.affiliation: Department of Anatomy, Faculty of Medicine and Surgery, University of Msida, Malta.
authors.forename: Pierre
authors.initials: P
authors.lastname: Schembri-Wismayer
authors.affiliation: Department of Restorative Dentistry, Faculty of Dental Surgery, University of Msida, Malta. Electronic address: josette.camilleri@um.edu.mt.
authors.forename: Josette
authors.initials: J
authors.lastname: Camilleri
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry / Q000494:pharmacology; D002130:Calcium Phosphates / Q000737:chemistry / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D004338:Drug Combinations; D017886:Durapatite / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D008855:Microscopy, Electron, Scanning; D010006:Osteoblasts / Q000187:drug effects*; D010087:Oxides / Q000737:chemistry / Q000494:pharmacology*; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants / Q000737:chemistry / Q000494:pharmacology*; D017640:Silicates / Q000737:chemistry / Q000494:pharmacology*; D013052:Spectrometry, X-Ray Emission; D014961:X-Ray Diffraction
chemical_list: D017610:Calcium Compounds; D002130:Calcium Phosphates; D004338:Drug Combinations; C550603:EndoSequence root repair material; D010087:Oxides; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D017640:Silicates; C506393:tricalcium silicate; C494370:calcium phosphate, monobasic; D017886:Durapatite
keywords: Cell viability assay; characterization; dental material; leaching; primary osteoblasts