الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
In order to mimic the tooth periodontium which is composed of hard (alveolar bone & cementum) and soft tissue (periodontal ligament fibers & gingival), two 3D structures were selected. The Sol-Gel scaffold was used to represent the hard (alveolar bone) and Bio-Gide membrane to resemble the soft tissue components (periodontal ligament fiber) of the periodontium. Both 3D structures were seeded with cells and arranged in a bi-layered construct. This bi-layered construct was left in such arrangement for 2 weeks in culture and cells were allowed to grow within it. This bi-layered construct was seeded with HPDLCs of adult stem cells that can differentiate into different lineages. The HPDLCs were obtained from extracted healthy wisdom teeth and were seeded at passage 4 dynamically using Macs Mix tube rotator. After 2 weeks in culture, continous compressive forces (7.2g&12.2g) were applied to the bi-layered construct using the continous compression weight approach using a specially designed loading system. The growth and differentiation of HPDLCs within the bi-layered construct was detected using the Live/dead imaging of each of the components of the bi-layered construct separately. In addition cytotoxicity of the construct was quantitatively assessed using LDH assay. Mechanical testing of the bi-layered construct was done using LLOYD universal testing machine for both seeded and un seeded bi-layered construct.
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Relative change in gene expression was determined using qRT-PCR for
osteoclastogenesis, osteoblastogenesis, pain, inflammatory and cementum
markers at 6h, 24h and 24h loading followed by 2h without load.
The results obtained from this study could lead to some conclusions among
which :
HPDLCs had a biocompatible 3D environment within the bi-layered
construct as evident from the live/dead imaging. The Cytotoxicity of
the bi-layered construct was insignificant as evident by the LDH assay
values.
The ephrin/EPH pathway contributes to the bone remodeling process
on the compression side during force application.
Pain marker (TAC1) showing up regulation following application of
compressive force as soon as 6h and continues throughout the 24h of
the study. However the removal of the compressive force leads to
immediate down regulation of the pain marker (TAC1).
The external root resorption that accompanies orthodontic tooth
movement is a feature that is associated with force application
(CEMP1) showed up regulation under compressive force and even
when force was released for a short period of time (2h).
The pro inflammatory cytokines (PGE2) released during compressive
force application was up regulated in the BGC only of the bi-layered
construct; hence SGC reduced inflammatory process.
There was a remarkable difference in the gene expression between the
BGC and SGC under compressive force. This study has demonstrated
that the bi-layered construct can be used as a successful in-vitro study
model to study compressive orthodontic forces.
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Q RT PCR /Live- dead
imaging/ LDH assay
Figure (41): Hierarchy demonstrating a summary for the steps that have
been carried out through this study