Effects of Different Powder to liquid Ratios on the Push out Bond Strength of CEM Cement on Simulated Perforations in the Furcal Area

BACKGROUND Proper bond strength to dentin is one of the properties of biomaterials used for therapeutic purposes such as repair of furcal perforations. The aim of the present study to evaluate the effects of different powder to liquid ratios of Calcium-enriched mixture (CEM) on the push-out bond strengths in simulated perforations in the furcal area and compare it with Mineral trioxide aggregate (MTA). MATERIAL AND METHODS Furcal perforations, measuring 1.3 mm in diameter and 2 mm in height, were prepared in 120 mandibular first molars. Then the samples were randomly assigned to two groups (n=60). MTA and CEM cement were used for the repair of perforations in groups 1 and 2, respectively. Each group was divided into 3 subgroups based on the powder to liquid rations as follows: subgroup 1 (W/P) , 1:2; subgroup 2, 1:3; and subgroup 3, 1:4. After mixing and placing the materials in the perforation area, the samples were placed in closed containers at 37°C and 100% relative humidity for one week. A universal testing machine was used to determine the bond strength values. After recording the standard deviations, data were analyzed with two-way ANOVA. Statistical significance was set at P<0.05. RESULTS In the MTA and CEM groups the highest push-out bond strength values were recorded in the third (W/P: 1:4) and first (W/P: 1:2) subgroups, respectively. There were significant differences in both groups between the ratios mentioned above and the other ratios (P<0.05). CONCLUSIONS Under the limitations of the present study, an increase in the powder-to-liquid ratio in CEM cement resulted in a decrease in bond strength, contrary to MTA. Key words:CEM, Perforation, Powder-to-liquid ratio, push-out bond strength, MTA.