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The Expressions of MMP-2 and MMP-9 in Human Denal Pulps

Author: LiuZuo
Tutor: XiangXueRong
School: Chongqing Medical University
Course: Clinical Stomatology
Keywords: MMPs Dental pulp Immunohistochemistry Pulpitis Orthodontics
CLC: R78
Type: Master's thesis
Year: 2008
Downloads: 95
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Abstract

Background:Extracellular matrix(ECM) is a substance made of bio-macromolecules which is synthetized and excreted to extracellular by odontoblasts and fibroblasts of dental pulp.It spreads among the cells and the surface of cells.Its chemical composition is a port to explore the metabolic activities and functions of pulp cells.Matirx metalloproteinases(MMPs) produces key marked effects during metabolic processes of pulp tissues ECM.It’s the important factor of tissue damage mechanism in pulposis process.Its genetic expression, protein synthesis and activity expression are subjected to accommodations of many factors.It can provide new train of thoughts for healing pulposis by investigating the MMPs.While the orthodontic forces are convenience,the blood vessels of root tip are pressed slightly,the pulp tissues come about to hyperemia in slight degree and sensitiveness to the variation of temperature.Sometimes,the pulp vitality decreases.Nevertheless,there is no remarkable change of endodontitis. For the time being,the research for the expressions of MMPs in dental pulp effected by orthodontic forces is still a gap.It is necessary to explore the MMPs’expressions of dental pulps in different conditions further,what factors influence them,and how the influences go.Objective:The method of immunohistochemistry was adopted.Studied the expressions of MMP-2 and MMP-9 in human dental pulps while they are normal, inflamed and under the effections of orthodontic forces.Probed the roles of MMPs activated in pathogenesis for inflammatory reaction of dental pulp.This study can provide important experimental evidence for effective antagonized mechanisms to MMPs,for preventing the deleterious effects of MMPs done to ECM,and for mitigating inflamed pains of dental pulps by preventing ECM degradation and reliefing inflamed pains.Materials and Methods:1.Selected 20 teeth which were healthy premolares extracted because of orthodontic treatments and healthy third molares extracted for needs. Made microtome sections after essays dealing.Used immunohistochemical streptavidin peroxidase method(SP method), analysed the expressions of MMP-2 and MMP-9 by analysing images and half-quantitative analysis.2. Selected 20 teeth which were healthy premolares extracted because of orthodontic treatments and healthy third molares extracted for needs as nomal group.Selected 20 third molares that clinical diagnoses were endodontitis and had no worth remaining as inflamed group. Used immunohistochemical streptavidin peroxidase method(SP method), analysed the expressions of MMP-2 and MMP-9 by analysing images and half-quantitative analysis.3. Selected 10 orthodontic patients(5 male and 5 female) ,decided which orthodontic teeth should be extracted before orthodontic treatments had started.Chose one side of them,and adopted routine orthodontic forces about 20-25g.Extracted the teeth within 1 to 7 days after orthodontic forces had been used.There were 20 teeth as under-forces group. The other side of the pre-extracted teeth did not use any orthodontic forces.There are also 20 teeth as homologizd control group. Selected 20 third molares that clinical diagnoses were endodontitis and had no worth remaining as inflamed group.Used immunohistochemical streptavidin peroxidase method(SP method), analysed the expressions of MMP-2 and MMP-9 by analysing images and half-quantitative analysis.Results:1.In healthy pulps,MMP-2 and MMP-9 mainly expressed in cytoplasts of odontoblasts and fibroblasts.The expressions were weakly positive.The central areas expressed more manifest than the peripheral one.The expression level of MMP-9 was higher than the MMP-2. Half-quantitative analysis:the positive constituent ratio of MMP-2 was 90.00%,and of MMP-9 was 100.00%. 2.There were MMP-2 and MMP-9 expressions in healthy and inflamed pulps.In healthy pulpal tissues,there were less positive cells with MMP-2 and MMP-9 than in inflamed pulps.In inflamed pulps, there were expressions of MMP-2 and MMP-9 in odontoblasts,fibroblasts and vascular endothelial cells.The areas of inflamed cells were positively expressed. The expression level of MMP-9 was also higher than the MMP-2. Half- quantitative analysis:in inflamed pulps,the expressions of MMP-2 and MMP-9 were heightened.Compared with normal group,the differences had statistical significance(P<0.05).3.There were expressions of MMP-2 and MMP-9 in control,under- forces and inflamed groups. In control pulpal tissues,there were less positive cells with MMP-2 and MMP-9 than in under-forces pulps and inflamed pulps.In under-forces pulpal tissues, MMP-2 and MMP-9 mainly expressed in odontoblasts and fibroblasts.Analyzed with the magnitude of staining, the central areas expressed more manifest than the peripheral one. The expression level of MMP-9 was higher than the MMP-2. In under- forces pulps,the expressions of MMP-2 and MMP-9 were manifestly stronger than control one,but weaker than the inflamed one.Half- quantitative analysis: in under-forces pulps,the expressions of MMP-2 and MMP-9 were heighten.The expressions:control<under-forces<inflamed pulps.The differences among the three groups had statistical significance(P<0.05). Conclusions:MMP-2 and MMP-9 mainly expressed in cytoplasts of odontoblasts and fibroblasts in human dental pulps.In physiological conditions,the expression levels of MMP-2 and MMP-9 are low,and sustain the health of pulpal tissues by the balance between MMPs and TIMPs.After stimulated by inflammations, the expressions of MMP-2 and MMP-9 are heightened. It can show the inflamed level and processes.Because of high-expressions of MMPs in inflamed pulps,they are important factors of tissue damage mechanisms during the pathological processes of dental pulps. It can provide new train of thoughts for healing pulposis by investigating the MMPs.During orthodontic treatments, effected by the orthodontic forces, the dental pulps are in stringent state. The expressions of MMP-2 and MMP-9 are heightened.Although it does not cause the pulpitis,the dentists should pay more attention to this fact. The orthodontic treatments are based on intimately knowing the influence of orthodontic forces on patients’organisms and using biomechanic concepts correctly.Only by this means can we increase the efficiency and design the best proposal of therapy.

The Expressions of MMP-2 and MMP-9 in Human Denal Pulps

Abstract

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