الفهرس 
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Abstract
The purpose of the present study was to evaluate the effect of adding white Portland cement, in the ratio of 25% by weight, on the physical and biological properties of MTA Fillapex and compare it with the unmodified MTA Fillapex.
Evaluation of physical properties:
• Setting time test of the new sealer:
Five samples for each sealer were made, experimental sealer group recorded higher setting time mean value compared to MTA Fillapex group.
• Flow Evaluation of the new sealer:
Five samples were made for each sealer tested. Experimental sealer group recorded lower flow mean value than MTA Fillapex group mean value.
• Film thickness evaluation of the new sealer:
The difference of five measurements taken for each sealer in thickness of the two glass plates, with and without sealer, was recorded as the film thickness of the material. Experimental sealer group recorded higher film thickness mean value than MTA Fillapex group mean value.
• The solubility evaluation of the new sealer:
The experiment was repeated three times for each sealer. The percentage of weight loss of each sample was considered the solubility of the sealer. Exp. sealer group recorded higher solubility mean value than MTA Fillapex group mean value.
• Water absorption evaluation of the new sealer:
After 7 days, the samples were removed and weighed. Each weight measurement was repeated 3 times, and the mean was recorded (wet weight). Samples were blotted dry at 37C° for 72 hours until constant weight (the dry weight). Exp. sealer group recorded higher sorption mean value than MTA Fillapex group mean value.
• Compressive strength evaluation:
The dimensions of six specimens were confirmed using a digital caliper. Experimental sealer group recorded higher compressive strength mean value than MTA Fillapex group with a statistically in-significant difference between the groups.
• Diametral tensile strength evaluation :
Five samples were made by split metallic molds. Experimental sealer group recorded higher diametral tensile strength mean value than MTA Fillapex group.
• Push out bond strength test evaluation:
Experimental sealer group recorded lower push out bond strength mean value than MTA Fillapex group mean value.
Evaluation of biological properties:
• Cytotoxicity test: After interval times of incubation 24, 72 and 168 hrs, experimental sealer group recorded higher cytotoxic activity mean value compared to MTA Fillapex group with a statistically insignificant difference between the groups at all the follow up intervals.
Conclusions:
• Addition of Portland cement to MTA Fillapex increases its setting time.
• Addition of Portland cement to MTA Fillapex decreases its flow properties.
• Portland cement increases film thickness, solubility and water absorption when added to MTA Fillapex.
• Portland cement increases the diametral tensile strength of MTA Fillapex when added to it.
• Addition of Portland cement to MTA Fillapex lowers its push-out bond strength.
• On the other hand, addition of Portland cement to MTA Fillapex increases its compressive strength and cytotoxicity, though these increases are insignificant.