الفهرس 
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Abstract
The basis for regenerative medicine is the utilization of tissue engineering therapies. Regenerative endodontic procedures can be defined as biologically based procedures designed to replace damaged structures, including dentin and root structures, as well as cells of the pulp-dentin complex.
In the current study, twenty male albino rats were used to transplant forty root segments collected from freshly extracted human incisors and single rooted premolars. Root segments were grouped in two major groups each with two subgroups; control group receiving only the self-assembling polypeptide scaffold and experimental group receiving fluorescent labeled adipose derived mesenchymal stem cells embedded in self-assembling polypeptide scaffold. Afterwards regenerating the dentin pulp complex in the emptied root canal space was attempted and investigation of the newly formed tissues using haematoxylin and eosin immunocytoflourescence, Masson trichrome and scanning electron microscopy.
Examination of root transplants using haematoxylin and eosin revealed that root canal space of control group was filled with granulation tissue with no evidence of predentin formation and no observable odontoblast like cells. While root transplants of experimental group revealed the presence of a homogenous rim structure along the margin of dentin together with some odontoblast like cells along its margin, inside the root canal space an organized connective can be noticed with abundant vascular structures and numerous calcific masses.
Sections from subgroups 1A and 1B only were examined by immunofluorescence via phase contrast fluorescent microscope, after two months of transplantation, examination of specimens revealed that only tissues inside root constructs of experimental group originated from seeded ASC.
Examination of root transplants sections of control group stained by Masson trichromatic stain revealed almost no vasculature while formation of new collagen and invasion by cellular elements were observed. Whereas experimental group showed new collagen formation and cellular elements and in some areas the collagen was scattered, less organized and concentrated in the pulp core. After three months the formation of a well-organized connective tissue extending to almost all length of the root canal. There was a sharply demarcated layer resembling predentin observed on the pulpal side of dentin. The vascular supply was almost fully developed represented by large and small blood vessels with RBCs densely packed in these vessels.
Investigating the ultrastructure of samples using scanning electron microscope revealed that in control group the dentin scaffold interface showed no evidence of predentin formation, however with intimate contact in some areas and with narrow gap in other areas between scaffold architecture and dentin structure. Moreover, interdigitation between scaffold fibrils and dentinal tubules was noticed in other sections. Experimental group exhibited scaffold supported numerous connective tissue cells of various sizes and fibrous matrix and in some areas, the remnants of scaffold. adhesion between scaffold-supported tissue and dentin showed coherent bond in some regions The scaffold-dentin interface showed dentinal tubules seen invaded by fibrous tissue structure and cell like structure. Moreover there was a layer coating dentin at the pulpal side resembling predentin that thickened and became well defined after three months of transplantation.