title: Bioactivity, physical and chemical properties of MTA mixed with propylene glycol.
abstract: OBJECTIVE
  To investigate the physical (setting time, hardness, flowability, microstructure) and chemical (pH change, calcium release, crystallinity) properties and the biological outcomes (cell survival and differentiation) of mineral trioxide aggregate (MTA) mixed using different proportions of propylene glycol (PG) and water.
  
  
  METHODS
  White MTA was mixed with different water/PG ratios (100/0, 80/20 and 50/50). Composition (XRD), microstructure (SEM), setting time (ASTM C266-13), flowability (ANSI/ADA 57-2000), Knoop hardness (100 g/10 s) and chemical characteristics (pH change and Ca2+ release for 7 days) were evaluated. Cell proliferation, osteo/odontoblastic gene expression and mineralization induced by MTA mixed with PG were evaluated. MTA discs (5 mm in diameter, 2 mm thick) were prepared and soaked in culture medium for 7 days. Next, the discs were removed and the medium used to culture dental pulp stem cells (DPSC) for 28 days. Cells survival was evaluated using MTS assay (24, 72 and 120 h) and differentiation with RT-PCR (ALP, OCN, Runx2, DSPP and MEPE) and alizarin red staining (7 and 14 days). Data were analysed using one-way ANOVA and Tukey's post-hoc analysis (a=0.05).
  
  
  RESULTS
  The addition of PG significantly increased setting time, flowability and Ca2+ release, but it compromised the hardness of the material. SEM showed that 50/50 group resulted porous material after setting due to the incomplete setting reaction, as shown by XRD analysis. The addition of PG (80/20 and 50/50) was not capable to improve cell proliferation or to enhance gene expression, and mineralized deposition of DPSC after 7 and 14 days as compared to the 100/0.
  
  
  CONCLUSIONS
  Except for flowability, the addition of PG did not promote further improvements on the chemical and physical properties evaluated, and it was not capable of enhancing the bioactivity of the MTA.
authors.affiliation: Faculty of Dentistry, National University of Singapore, SG.
authors.forename: Vaishali Prakash
authors.initials: VP
authors.lastname: Natu
authors.affiliation: Faculty of Dentistry, National University of Singapore, SG.
authors.forename: Nileshkumar
authors.initials: N
authors.lastname: Dubey
authors.affiliation: Faculty of Dentistry, National University of Singapore, SG.
authors.forename: Gerald Choon Leong
authors.initials: GC
authors.lastname: Loke
authors.affiliation: Faculty of Dentistry, National University of Singapore, SG.
authors.forename: Teng Seng
authors.initials: TS
authors.lastname: Tan
authors.affiliation: Faculty of Dentistry, National University of Singapore, SG.
authors.forename: Wee Hsuan
authors.initials: WH
authors.lastname: Ng
authors.affiliation: Faculty of Dentistry, National University of Singapore, SG.
authors.forename: Chee Weng
authors.initials: CW
authors.lastname: Yong
authors.affiliation: Faculty of Dentistry, National University of Singapore, SG.
authors.forename: Tong
authors.initials: T
authors.lastname: Cao
authors.affiliation: Faculty of Dentistry, National University of Singapore, SG.
authors.forename: Vinicius
authors.initials: V
authors.lastname: Rosa
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D000704:Analysis of Variance; D017610:Calcium Compounds / Q000737:chemistry*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003782:Dental Pulp; D004338:Drug Combinations; D015870:Gene Expression; D006245:Hardness Tests; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000737:chemistry*; D019946:Propylene Glycol / Q000737:chemistry*; D060888:Real-Time Polymerase Chain Reaction; D012212:Rheology; D017640:Silicates / Q000737:chemistry*; D013234:Stem Cells / Q000187:drug effects; D013997:Time Factors
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D004338:Drug Combinations; D010087:Oxides; D017640:Silicates; C086631:mineral trioxide aggregate; D019946:Propylene Glycol