title: Effects of physiological environments on the hydration behavior of mineral trioxide aggregate.
abstract: Utilizing scanning electron microscope, X-ray diffraction (XRD) and microhardness tests, we evaluated how various physiological environments affect the hydration behavior and physical properties of mineral trioxide aggregate (MTA). We found that the microstructure of hydrated MTA consists of cubic and needle-like crystals. The former comprised the principal structure of MTA, whereas the later were less prominent and formed in the inter-grain spaces between the cubic crystals. MTA samples were hydrated in distilled water, normal saline, pH 7, and pH 5. However, no needle-like crystals were observed in the pH 5 specimens, and erosion of the cubic crystal surfaces was noted. XRD indicated a peak corresponding to Portlandite, a hydration product of MTA, and the peak decreased noticeably in the pH 5 group. The pH 5 specimens' microhardness was also significantly weaker compared to the other three groups (p<0.0001). These findings suggest that physiological environmental effects on MTA formation are determined, in part, by environmental pH and the presence of ions. In particular, an acidic environment of pH 5 adversely affects both the physical properties and the hydration behavior of MTA.
authors: School of Dentistry, College of Medicine, National Taiwan University, Chang Te Street, Taipei 10016, Taiwan, ROC.
authors: Yuan-Ling
authors: YL
authors: Lee
authors: Bor-Shiunn
authors: BS
authors: Lee
authors: Feng-Huei
authors: FH
authors: Lin
authors: Ava
authors: A
authors: Yun Lin
authors: Wan-Hong
authors: WH
authors: Lan
authors: Chun-Pin
authors: CP
authors: Lin
mesh_terms: D017607:Aluminum Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry*; D001826:Body Fluids / Q000737:chemistry*; D017610:Calcium Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D003738:Dental Cements; D004338:Drug Combinations; D006244:Hardness; D006863:Hydrogen-Ion Concentration; D008422:Materials Testing / Q000379:methods*; D008968:Molecular Conformation; D010087:Oxides / Q000138:chemical synthesis / Q000737:chemistry*; D044367:Phase Transition; D012387:Root Canal Filling Materials; D017640:Silicates / Q000138:chemical synthesis / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
chemical_list: D017607:Aluminum Compounds; D001672:Biocompatible Materials; D017610:Calcium Compounds; D003738:Dental Cements; D004338:Drug Combinations; D010087:Oxides; D012387:Root Canal Filling Materials; D017640:Silicates; C086631:mineral trioxide aggregate; D014867:Water