الفهرس 
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Abstract
The present study was done to evaluate a new formulation of H2O2 with traces of silver salts as an endodontic irrigant and in different combinations with other irrigants in terms of:
1. Antimicrobial efficacy.
2. Cytotoxicity.
3. Cleaning ability.
4. Changes in mineral content.
In this in-vitro study, 104 extracted maxillary anterior teeth were disinfected, decoronated and prepared using Protaper Universal rotary system. The teeth were sterilized then filled with a 24-hour pure culture suspension of E. faecalis and incubated at 37°c in sealed vials for 7 days .The teeth were then divided into 8 groups (n=13) according to different irrigant materials used: 3% Herisil, 7% Herisil, 5.25% NaOCl, 3% H2O2, combination of 5.25% NaOCl + 3% Herilsil, combination of 5.25% NaOCl + 7% Herisil, combination of 5.25% NaOCl + 3% H2O2, and saline. Paper points were used to collect bacterial samples to measure the antimicrobial effect of each group. Cytotoxicity of each group was measured by MTT after 24 and 72 hours.
Teeth were sectioned longitudinally to measure cleaning ability of each group. Eight halves of each group was then examined using light stereomicroscope at 40X magnification, coronal, middle and apical images were taken and analyzed using Image J computer software.
Another 40 extracted maxillary anterior teeth were used. They were divided into 8 groups (n=5) and immersed into the same irrigant materials as used before for 1 minute. Each group was then ground into fine powder particles and examined using XRD to evaluate the change in mineral content. While the irrigants were examines using flame atomic microscope to detect traces of Calcium and Phosphorus lost from dentin into the irrigants.
One-way ANOVA test showed that group 5 (3%Herlisil+ 5.25% NaOCl) showed the most powerful antimicrobial effect with the lowest number of CFU.All irrigants were cytotoxic to the fibroblast cells after both 24 and 72 hours test, however there was an increase in the cytotoxic effect of groups 3,4,6,7 and 8 with time.
Regarding the root canal cleanliness group 5 (3%Herlisil+ 5.25% NaOCl) showed the lowest mean value of debris between all irrigants under investigation. group 5 also showed the lowest mean value of debris in both middle and apical parts of the root canal, while group 1 had the lowest mean value of debris in the coronal third of the root canal.
Regarding minerals loss, group 2 (Herlisil7%) showed the highest amount of Ca and P loss, the results of XRD analysis showed no significant difference in the chemical formula of dentin samples after immersion in different irrigating solutions.
Conclusions:
Within the limitations of the study, the following conclusions could be withdrawn:
1. The mixture of 5.25% NaOCl + 3% Herlisil had the strongest anti-mircobial effect, while 3% Herlisil alone had a weaker effect among the irrigants under investigation.
2. All irrigants under investigation except for saline (control group), had a cytotoxic effect on fibroblasts after 24 and 72 hours.
3. The mixture of 5.25% NaOCl + 3% Herlisil had the best cleaning ability as it left the least amount of debris in the lumin of the canal, however, the difference between the irrigants under investigation was not statistically significant.
4. Using X-ray diffraction analysis, no significant difference was found in the chemical composition of the dentin samples after immersion in the irrigants under investigation, in comparison to the reference pattern of normal dentin.
5. The mixture of 5.25% NaOCl + 3% Herlisil and the mixture of 5.25% NaOCl + 7% Herlisil caused the least amount of Ca loss in comparison other irrigants under investigation except for saline (control group).
6. 7% Herlisil caused the highest amount of P loss, while 3 % Herlisil and 3% H2O2 caused the least amount of P loss in comparison other irrigants under investigation except for saline (control group).
Limitations:
Further studies are needed to gain more information about the composition of and action of Herlisil as a root canal irrigant.
According to the results of this study, Herlisil seems to be a promising irrigant due to its comparable antimicrobial effect,cytotoxicity, cleaning ability and change in mineral content to the most commonly used root canal irrigant (NaOCl) especially when used in mixture with NaOCl.