title: Study of two MTA cements.
abstract: BACKGROUND
  To determine and compare the pH, conductivity and calcium release of an experimental Portland cement (PE) consisting of trioxid mineral aggregate and a comercially available modified Portland cement (C.P.M.) after 1, 2, 3, 4, 8, 10, 15 and 30 days.
  
  
  METHODS
  Cements were mixed following the manufacturer's instructions, with a powder: liquid ratio of 3:1. Each cement was placed in 12 PVC tubes 1 mm in diameter and 10 mm in length and allowed to set. Four empty tubes were used as negative controls. Tubes were submerged in plastic flasks containing 10 ml deionized water and stored at 37 C and 100% humidity. After 1, 2, 3, 4, 8, 10, 15 and 30 days tubes were removed from the flasks and these were refilled with deionized water. We measured pH, conductivity and calcium content of the recovered solution. Data were analyzed using repeated measures ANOVA.
  
  
  RESULTS
  pH was 0.3 units more alkaline with PE cement (p=0.023). pH experienced a slight decrease with time (p<0.001), independently of the cement type (p>0.05). Conductivity of PE and CPM cements diminished at 4 days and almost recovered at 30 days (p<0.001). PE cement had a higher conductivity (p<0.001). Calcium release diminished from the first day and recovered at 30 days (p<0.001) similarly for both cements (p>0.05).
  
  
  CONCLUSIONS
  PE cement raised pH slightly more and had higher conductivity than CPM. Calcium release diminished after the first day and recovered at 30 days, similarly for both cements.
authors.affiliation: University of Barcelona, Department of Endodontics, S chool of Dentistry, Feixa LLarga s/n, Hospitalet de Llobregat, 08097- Barcelona, Spain, eberastegui@gmail.com.
authors.forename: Esther
authors.initials: E
authors.lastname: Berástegui
authors.forename: Eduard
authors.initials: E
authors.lastname: Valmaseda-Castellón
authors.forename: Vicente
authors.initials: V
authors.lastname: Faus
authors.forename: María-Luisa
authors.initials: ML
authors.lastname: Ballester
authors.forename: Leonardo
authors.initials: L
authors.lastname: Berini-Aytés
mesh_terms: D017607:Aluminum Compounds; D017610:Calcium Compounds; D003738:Dental Cements; D004338:Drug Combinations; D008422:Materials Testing; D010087:Oxides; D017640:Silicates; D013997:Time Factors
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D003738:Dental Cements; D004338:Drug Combinations; D010087:Oxides; D017640:Silicates; C472247:accelerated Portland cement; C086631:mineral trioxide aggregate