title: Magnesium phosphate cements for endodontic applications with improved long-term sealing ability.
abstract: OBJECTIVE
  To characterize three radiopaque Magnesium Phosphate Cements (MPCs) developed for endodontic purposes.
  
  
  METHODS
  Three experimental MPCs containing Bi2 O3 were formulated. The experimental cements, which consisted of mixtures of magnesium oxide with different phosphate salts, were characterized for setting time, injectability, porosity, compressive strength and phase composition. The long-term sealing ability of the experimental MPCs applied in single-rooted teeth as root canal filling material or as sealer in combination with gutta-percha was also assessed using a highly sensitive fluid filtration system. A mineral trioxide aggregate (MTA) cement was used as control. Statistical analysis was performed with two- or three-way analysis of variance (anova) and Tukey's test was used for comparisons.
  
  
  RESULTS
  The addition of 10 wt% Bi2 O3 within the composition of the MPCs provided an adequate radiopacity for endodontic applications according to ISO 6876 standard. The reaction products resulting from the MPCs were either struvite (MgNH4 PO4 ·6H2 O) or an amorphous sodium magnesium phosphate. The porosity of the three MPCs ranged between 4% and 11%. The initial setting time of the experimental cements was between 6 and 9 min, attaining high early compressive strength values (17-34 MPa within 2 h). All MPC formulations achieved greater sealing ability than MTA (P < 0.05) after 3 months, which was maintained after 6 months for two of the experimental cements (P < 0.05).
  
  
  CONCLUSIONS
  These MPCs had adequate handling and mechanical properties and low degradation rates. Furthermore, a stable sealing ability was demonstrated up to 6 months when using the cement both as root filling material and as sealer in conjunction with gutta-percha.
authors: Biomaterials, Biomechanics and Tissue Engineering Group, Department of Materials Science and Metallurgy, Technical University of Catalonia, Barcelona, Spain; Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain.
authors: G
authors: G
authors: Mestres
authors: F S
authors: FS
authors: Aguilera
authors: N
authors: N
authors: Manzanares
authors: S
authors: S
authors: Sauro
authors: R
authors: R
authors: Osorio
authors: M
authors: M
authors: Toledano
authors: M P
authors: MP
authors: Ginebra
mesh_terms: D003738:Dental Cements / Q000737:chemistry*; D004708:Endodontics; D017616:Magnesium Compounds / Q000737:chemistry*; D010710:Phosphates / Q000737:chemistry*; D010895:Pit and Fissure Sealants; D014961:X-Ray Diffraction
chemical_list: D003738:Dental Cements; D017616:Magnesium Compounds; D010710:Phosphates; D010895:Pit and Fissure Sealants; C030781:magnesium phosphate
keywords: endodontic applications; magnesium phosphate cement; radiopacity; root canal filler; root canal sealer; sealing ability