الفهرس 
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Abstract
The aim of this study was to evaluate the effect of different irrigation protocols on the release of Transforming growth factor β1 from the dentin matrix and the regenerative potential of stem cells.
A total of 48 human permanent single rooted anterior teeth were used in this study. Decoronation was done, two discs from each root were obtained for each evaluation part of the experiment and randomly allocated to 5 groups with different irrigation protocols.
Part I: Evaluation of TGF-β1 release:
The discs were kept at 37º C for 1 day and at the end of the time point, medium from samples was collected and filtered. The solution was removed, immediately frozen in liquid nitrogen, and stored at -80ºC. After completion of sample collection, all samples were thawed and subjected to growth factor quantification by using an ELISA test system for TGF-β1.
Part II: Regenerative potential of SHED:
Samples were collected for SHED isolation from deciduous exfoliated teeth. After characterization, identification and passaging of stem cells, root disc model construct for animal study was prepared using a scaffold. The root disc constructs from each six groups (including the previous 5 groups and a negative control group) were then implanted into the subcutaneous space of the incision sites in each rat. Each rat received five tooth constructs, one from each group. The wounds were sutured to obtain primary closure.
After 30 days, the root discs were retrieved and sent for histological staining by H&E, masson trichrome and immunohistochemical staining for evaluation and analysis of total blood vessels count, area fraction of the newly formed collagen fibers and observation of odontoblast like cells.
Results:
Results showed that samples irrigated by (Chorohhexidine gluconate 2% & 17% EDTA) to have a significantly higher value of released (TGF-β1) than samples of other groups. The highest total blood count was shown in Chorohhexidine gluconate 2% & 17% EDTA group which had a significantly higher value than samples irrigated by 5.5% NaOCl & 17% EDTA. The highest area fration was showed in samples irrigated by deionized water which had a significantly higher value than samples irrigated by Chorohhexidine gluconate 2%. There was a positive weak significant correlation between released (TGF-β1) and blood vessels count.
Meanwhile there was no significant correlation between released (TGF-β1) and area fraction of newly formed collagen fibers. Observational data obtained from nestin stained sections reveled that all sections obtained from the experimental groups, including the positive control group, showed diverse amounts of positive reaction for the newly formed odontoblast like cells. Samples of deionized water group appeared to show higher positive reaction than other groups