الفهرس 
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Abstract
This study was conducted to evaluate the antibacterial effect of three different pulp capping materials, Biodentine™, White ProRoot® mineral trioxide aggregate (MTA) and calcium hydroxide (Dycal®) against two reference strains of cariogenic bacteria, Streptococcus mutans and Lactobacillus acidophilus. Three 96-U shaped well microtiter plates, one for each group of the tested materials, were used and 18 wells (6 wells for each tested material) were coated with an equal amount of each tested material by using a small sterile dental spatula to ensure a uniform surface area. The samples were divided into 3 groups according to the time interval between mixing and testing; group1 freshly mixed tested materials, while group 2 and 3 were allowed to set for 24 hours and 7 days, respectively in a humid atmosphere at 37°C before testing. Each group was subdivided into two subgroups according to the type of bacteria used. In subgroup A where Streptococcus mutans was used as the inoculum while Lactobacillus acidophilus was used as the inoculum for subgroup B. A 50 μl bacterial suspension was placed on the tested materials in eighteen wells (six wells for each tested material), while another 50 μL of bacterial suspensions were placed in uncoated wells (6 uncoated wells in the same microtiter plate for each group of the tested materials) were used as control.
Then after incubation at 37°C for 1 hour, evaporation of the suspension was evident and ensured direct contact between the bacteria and the tested material surface.
A 50 μl of brain heart infusion broth was then added to these 18 wells. Streak plate method using sterile calibrated loop was used to spread the bacteria over the surface of a blood agar plate. The inoculated agar plates were incubated in the incubator at 37°C for 48 hours anaerobically in an anaerobic jar with the use of anaerobic gas pack. After 48 hours incubation period at 37°C, the numbers of colony-forming units on the agar plates were counted using digital colony counter and the colony-forming units/ml (CFU/ml) were calculated for each tested material.
The test was repeated 3 times for each tested material to ensure reproducibility.
The same experiment was done with Lactobacillus acidophilus bacteria as a tested microorganism.
Results were recorded, tabulated and statistically analyzed using one-way analysis of variance (ANOVA) followed by Tukey test for multiple comparisons to compare the differences between biodentine, MTA and calcium hydroxide.
The results of this study showed that when using Streptococcus mutans as the tested bacteria all tested materials in the three groups showed significant antibacterial activity against S .mutans compared with the control group. No significant difference was found between Biodentine™ and White ProRoot® mineral trioxide aggregate in the three groups. Biodentine and ProRoot® MTA showed significant antibacterial activity compared to Dycal® after 24 hours and seven days of mixing.
However, there was no statistically significant difference between biodentine and MTA compared to Dycal® when used immediately after setting.
When using Lactobacillus acidophilus as the tested bacteria, all tested materials in the three groups showed significant antibacterial activity against L. acidophilus compared to the control group. Biodentine™ has no significant difference in its antibacterial activity compared to both ProRoot® MTA and Dycal® samples when used immediately after setting and after 24 hours of mixing. While Biodentine™ when tested after 7 days of mixing showed statistically significant difference in their antibacterial activity compared to both ProRoot® MTA and Dycal.