Effect of acidic environment on the push-out bond strength of calcium-enriched mixture cement.
BACKGROUND
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
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 pairwise 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.


CONCLUSIONS
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.
Department of Endodontics, Dental School, Shiraz University of Medical Sciences, Shiraz, Iran;
Fereshte
F
Sobhnamayan
Department of Endodontics, Dental School, Shiraz University of Medical Sciences, Shiraz, Iran;
Safoora
S
Sahebi
Students' Research Committee, Dental School, International Branch, Shiraz University of Medical Sciences, Shiraz, Iran;
Misagh
M
Naderi
Department of Endodontics, Dental School, Shiraz University of Medical Sciences, Shiraz, Iran;
Nooshin Sadat
NS
Shojaee
Department of Maxillofacial Medicine, Dental School, Tehran University of Medical Science, Tehran, Iran.
Najmeh
N
Shanbezadeh
Acidic Environment; CEM cement; Calcium-Enriched Mixture; Push-Out Bond Strength; Root-End filling