Study Of Expression Of ODF And OCIF During Orthodontic Periodontium Remodeling

Orthodontic tooth movement is resulted from periodontal tissue remodeling induced by mechanical strength stimulation, moving in a certain direction. Mechenical strength plays an important role in this action. Periodontal ligament cells between alveolar and teeth response directly to the mechanical force.It has been comfirmed that periodontal ligament cells could express osteoclast differentiation factor(ODF) and osteoclasto-genesis inhibitory factor(OCIF) in vitro and in vivo-the two key factors in regulating osteoclast differentiation and action in loacal bone microenvironment .The expression of ODF increases with the existence of some bone resorption stimulating factors;ODF binds with RANK existing on the membrane of osteoclast precursor,causing cascade reaction, thus the osteoclast is activated. OCIF binds with ODF competitively,blocking the binding of ODF and RANK,so the differentiation and maturation of osteoclast are restrained. Bone resorption by osteoclast is the first step of orthodontic tooth movement, alternative resorption and proliferation of alveolar cause tissue remodeling.The molecular biology mechanism of tissue remodeling under mechanical strengthis not clear that progressive study should be carried out to clarify how the mechanical signal transform to biological signal and what' s the function of bone resorption stimulating factor in this process.Thus this study focus on the the effects of mechanical forces and 1,25- (OH) 2D3 on the expression of ODF and OCIF by periodontal tissue in vivo and periodontal ligament cell and osteoclast in vitro,thus clarify the molecular biology mechenism of tissue remodeling,and explore a new way in orthodontic clinic to accelerate the dental movement speed by adding some ectogenesis stimulating factors. The main works are as follow:1.The expression of ODF and OCIF by periodontal tissue under strain force in rats .Objective:To investigate the changes of ODF and OCIF expression by periodontal tissue during orthodontic tooth movement in rats and detect the relationship between ODF , OCIF and orthodontic periodontal tissue remodeling. Methods:Orthodontic appliance was placed between the right maxillary first molar and maxillary central incisors of rat;in situ hybridization and image analyses were performed at 0, 1, 3, 5, 7 days after orthodontic tooth movement. Results:The expression of ODF and OCIF were weak in normal periodontal tissue; in strain area,OCIF expression increased in 3 days,reached the maximum at day 5,new bone formation could be seen at that time; ODF expression decreased during orthodontic tooth movement but not significantly. Conclusion: ODF and OCIF participated in orthodontic periodontal tissue remodeling. OCIF expression increased in strain area in a time-dependent manner. 2.Effects of strain force on the expression of ODF and OCIF by human periodontal ligament cells.Objective: To explore the molecular mechanism of periodontal tissue remodeling during orthodontic tooth movement by investigating the effects of strain force on the expression of ODF and OCIF in human periodontal ligament cells (HPDLCs). Methods: HPDLCs were subjected to cyclic strain force for 0, 6, 12 and 24 hours in this experiment, mRNA expression of ODF and OCIF were determined by RT-PCR. Results: The expression of ODF mRNA was reduced significantly and expression of OCIF mRNA was increased not significantly. Conclusion:Strain force could adjust the proportion of expression of ODF to expression of OCIF. Thus the bone metabolism was adjusted.3. Effects of 1, 25- (OH) 2D> stimulation on the expression of ODF and OCIF by human periodontal ligament cells.Objective: To clarify the molecular mechanism of periodontal tissue remodeling during orthodontic tooth movement by investigating the effects of 1, 25- (OH) 2D3 on the expression of ODF and OCIF in human periodontal ligament cells (HPDLCs). Methods: HPDLCs were subjected to different doses of 1, 25- (OH) 2D3 (0, 10-10, 10-8, 10-6mol/L) for 24 hours in this experiment, mRNA expression of ODF and OCIF were determined by s...