Ahmed, G. M., E. A. Abouauf, N. AbuBakr, A. M. Fouad, C. E. Dörfer, and K. M Fawzy El-Sayed, "Cell-Based Transplantation versus Cell Homing Approaches for Pulp-Dentin Complex Regeneration.", Stem cells international, vol. 2021, pp. 8483668, 2021. Abstract

Regenerative dentistry has paved the way for a new era for the replacement of damaged dental tissues. Whether the causative factor is dental caries, trauma, or chemical insult, the loss of the pulp vitality constitutes one of the major health problems worldwide. Two regenerative therapies were introduced for a fully functional pulp-dentin complex regeneration, namely, cell-based (cell transplantation) and cell homing (through revascularization or homing by injection of stem cells in situ or intravenously) therapies, with each demonstrating advantages as well as drawbacks, especially in clinical application. The present review is aimed at elaborating on these two techniques in the treatment of irreversibly inflamed or necrotic pulp, which is aimed at regenerating a fully functional pulp-dentin complex.

Ahmed, G. M., E. A. Abouauf, N. AbuBakr, A. E. E. Arab, and K. Fawzy El-Sayed, "Stem Cell-Based Tissue Engineering for Functional Enamel and Dentin/Pulp Complex: A Potential Alternative to the Restorative Therapies", Stem Cells: Springer, Cham, 2021.
Ahmed, G. M., A. A. El-Baz, A. A. Rahman, and A. K. Shalaan, "expression levels of matrix metalloproteinase-9 and gram-negative bacteria in symptomatic and asymptomatic periapical lesions", Journal of Endodontics, vol. 39, issue 4, pp. 444-448, 2013. Abstractmy_mmp-9_papaer.pdf

The aim of this study was to test the hypothesis that the expression of matrix metalloproteinase (MMP)-9 is significantly elevated in patients with symptomatic apical periodontitis and to correlate this with the detected amount of gram-negative bacteria.
METHODS:
Twenty-six patients with periapical lesions involving at least 2 teeth were included in this study. The patients were divided into 2 groups: the symptomatic (SYM) group included 13 patients expressing pain with periapical lesions, and the asymptomatic (ASYM) group included 13 patients expressing no pain. Root canal treatment was performed followed by endodontic surgery and periapical lesion collection. Periapical lesions were serially cut into 4-μ sections. Some sections were processed for histologic examination using hematoxylin-eosin stain. Other sections were processed for immunohistochemical examination. For MMP-9, the area fraction of the positive cells was measured, and the percentage of the MMP-9-immunopositive area to the total area of the microscopic field was calculated. For gram-negative stain cells, the number of cells showing the pink-red color was counted per microscopic field. The Student's t test was used to compare the SYM and ASYM groups. The Pearson correlation coefficient was used to determine a significant correlation between the number of cells and the MMP-9 level. The significance level was set at P ≤ .05.
RESULTS:
The SYM group showed a statistically significantly higher mean number of gram-negative cells (P = .001) and MMP-9 area percent (P < .001) than the ASYM group. There was a statistically significant positive (r = .927) correlation between the number of gram-negative cells and the MMP-9 area percent (P< .001).
CONCLUSIONS:
There is good evidence to suspect a significant role of gram-negative bacteria and MMP-9 in symptomatic periapical lesions.
Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

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