الفهرس 
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Abstract
Stem cells are immature, unspecialized cells that can differentiate into many different cell types. SHEDs are a type of dental pulp stem cells that are accessible and are multipotent mesenchymal stem cells with high proliferation potency. SHEDs are one of the candidate cell types for tissue regeneration studies. Vital pulp therapy based on using stem cells has promising research and therapeutic applications in dentistry.4,9,10
The aim of this study was to evaluate the effect of different capping materials like Calcium Hydroxide, Glass Ionomer and TheraCal LC on the stem cells after isolation from human dental pulp of the primary teeth.
Clinical examination was performed and following the inclusion and exclusion criteria and the ethical committee guidelines, primary teeth were collected from the outpatient clinic of the Department of Pediatric Dentistry and Dental Public Health, Faculty of Dentistry, Ain Shams University
The extracted teeth were immediately transported on ice in a closed box to the lab at the unit of Biochemistry and Molecular Biology, the Department of Biochemistry, Faculty of Medicine, Cairo University for stem cells isolation.
The teeth were split open, and the pulp was gently removed, and cell culture procedure was performed in a sterile environment following the guidelines of established protocol.
The cultured stem cells (SHED) were divided into four groups (group 1control- group II Ca hydroxide, group III Glass ionomer and group IV Theracal LC) with 8 specimens in each group. All materials were prepared according to the manufacturer’s instructions.
Then Viability and Proliferation rate of stem cells was evaluated by MTT cell proliferation assay. Differentiation was evaluated by Alkaline phosphatase enzyme activity and Dentin matrix protein Gene expression both measured by quantitative real time PCR. Also, Morphological assessment of any calcific deposits was done by Alizarin Red S staining. Each test was evaluated twice, after 7 and after14 days.
The results showed success of isolation of Stem cells from human exfoliated deciduous teeth. And showed increased proliferation rate with all materials compared to the control group after 7 and 14 days. With Theracal LC showing the highest proliferation rate.
After one-week Theracal showed the highest significant values of ALP enzyme activity and DMP-1 gene expression compared to all other groups. After two weeks similar results appeared except that Ca Hydroxide showed comparable results to that of Theracal. And the Glass ionomer being the least of the three materials compared to the control after 7 and 14 days.
The results of The Alizarin Red S stain showed increase in the calcific deposit outside and inside the cell for the three materials with gradual increase over time from 7 to 14 days compared to the controls.
According to the results of this study deciduous teeth are a rich source of a valuable stem cells that show promising hopes for tissue regeneration.
Conclusion
Based on the results and within the limitations of this study, the following conclusions may be reached:
• Primary teeth offer a chance for noninvasive postnatal stem cells collection of a powerful type of Stem cells (SHED)
• SHED can be a valuable source of stable differentiated odontoblastic like cells. Their ability of inducing hard tissue formation offer an alternative method to save teeth with compromised structural integrity.
• The three materials under the study are biocompatible, maintain cell viability and stimulate proliferation and differentiation of stem cells from human exfoliated deciduous teeth (SHED).
• The overall results of this study showed that Theracal LC allow better proliferation of SHEDs than Dycal Ca (OH)2 and Fuji IX GIC although non-significant.
• The ALP activity and DMP-1 gene expression were significantly higher in Theracal group than any other groups after 1 week of culture denoting better odontoblastic differentiation.
• Theracal LC and DyCal Ca (OH)2 showed no significant difference in ALP activity or DMP-1 gene expression after 2 weeks of culture, while Fuji IX GIC showed the least ALP activity and DMP-1 gene expression especially after 2 weeks of culture.
Recommendations
Based on the limitations of the current study, the following could be recommended:
• Deciduous teeth are a valuable source of stem cells, more banks should be available, and more studies are needed to cut down the cost of stem cells storing.
• TheraCal LC showed promising results in calcified tissue formation, so more clinical studies are still needed.
• Caution in the usage of GICs in restorative dentistry, especially if used near pulp tissue.
• Further studies with longer culture periods are needed.
• Further studies with clinical evaluation are recommended.