effect of acidic environment on the push-out bond strength of calcium-enriched mixture cement

introduction: this laboratory study was performed to evaluate the effect of different acidic ph values on the push-out bond strength of calcium-enriched mixture (cem) cement. methods and materials: forty-eight root dentin slices were obtained from freshly extracted single rooted human teeth and their lumen were instrumented to achieve a diameter of 1.3 mm. then, cem cement was mixed according to manufacturers’ instruction and placed in the lumens with minimal pressure. the specimens were randomly divided into four groups ( n =12) which were wrapped in pieces of gauze soaked in either synthetic tissue fluid (stf) (ph=7.4) or butyric acid which was buffered at ph values of 4.4, 5.4 and 6.4. they were then incubated for 4 days at 37°c. the push-out test was performed by means of the universal testing machine. specimens were then examined under a digital light microscope at 20× magnification to determine the nature of the bond failure. the data were analyzed using the kruskal-wallis test followed by dunn’s test for pair - wise comparisons. results: the highest push-out bond strength (10.19±4.39) was seen in the ph level of 6.4, which was significantly different from the other groups ( p <0.05). the values decreased to 2.42±2.25 mpa after exposure to ph value of 4.4. conclusion: lower ph value of highly acidic environments (ph=4.4), adversely affects the force needed for displacement of cem cement; while in higher ph values (ph=6.4) the bond-strength was not affected. cem cement is recommended in clinical situations where exposure to acidic environment is unavoidable.