title: Physical evaluation of a new pulp capping material developed from portland cement.
abstract: BACKGROUND
  This study examined the effects of addition of 10% and 25% by weight calcium hydroxide on the physicochemical properties of Portland cement associated with 20% bismuth oxide in order to develop a new pulp capping material.
  
  
  METHODS
  The solubility, pH value, setting time, compressive strength, and push out bond strength of modified Portland were evaluated and compared to those of mineral trioxide aggregate (MTA) and Portland cement containing 20% bismuth oxide.
  
  
  RESULTS
  The statistical analysis was performed with ANOVA and Duncan's post-hoc test. The results show that the strength properties and push out bond strength of Portland cement were adversely affected by addition of calcium hydroxide especially with a ratio of 25 wt%, however, the setting time and pH were not affected. MTA showed a statistically significant lower setting time than other cements (P≤0.001). Portland cement with bismuth oxide and Port Cal I showed a statistically significant higher Push out Bond strength than MTA and Port Cal II (P=0.001).
  
  
  CONCLUSIONS
  Taking the setting time, push out bond strength and pH value into account, addition of 10 wt% calcium hydroxide to Portland cement associated with 20% bismuth oxide produces a new pulp capping material with acceptable physical and adhesive properties. Further studies are recommended to test this cement biologically as a new pulp capping material.
  
  
  BACKGROUND
  Calcium hydroxide, MTA, Portland cement, setting time, solubility, strength.
authors.affiliation: MSc. Assistant lecturer october 6 university, 3 mohamed kamel morsy dokki, Giza Egypt.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Negm
authors.affiliation: PhD, Professor of Endodontics. Department of Endodontics. Faculty of Dentistry. Ain Shams University. Cairo. Egypt.
authors.forename: Ehab
authors.initials: E
authors.lastname: Hassanien
authors.affiliation: PhD, Professor. Department of Surgery, Anesthesiology and Radiology, Faculty of Veterinary Medicine, Cairo University, Giza-Egypt.
authors.forename: Ashraf
authors.initials: A
authors.lastname: Abu-Seida
authors.affiliation: PhD, Lecturer of Endodontics. Department of Endodontics. Faculty of Dentistry. Ain Shams University. Cairo. Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Nagy