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.
Material and 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
