Expression And Significance Of MMP-8 In Caries Process

In the process of carries formation, demineralization and degradation of organic matrix due to protease takes place at the same time. Researchers noted that pathogenic bacteria that cause dental caries directly hydrolyze ECM (extracellular matrix) by releasing proteolytic enzymes and also cause damage to tissue by five different avenues including MMPs method. MMPs methods are a group of zinc ion dependent endopeptidase, Collagenase and MMP-8 which have been suggested to play an important role in the carries process, periodontal disease and degradation of matrix within the bone tissue.MMP-8 is mainly synthesized and secreted by fibroblast, chondrocyte, endothelial cell, macrophage, leukocytes and so on. In Recent years, studies have found that both enameloblast and odontoblast expressed MMPs. MMPs can be detected in host body and is able to be activated in host saliva at low PH value.Artificial model of dental caries in vitro shows that dental caries can be formed after demineralization and destruction of organic matrix, which is bound to be witnessed after demineralization of dentin. The phenomenon of proteolytic enzymes hydrolyzation of organic matrix is capable of enhancing susceptibility of dentine caries depending acidity. Softened dentine presenting within artificial caries lesion has also expresses MMP-8. It is suggested that bacterial acids cause demineralization of enamel and activation of MMPs and that dentine collagen fibers that are exposed the dentine collagen fibers to acid environment which can easily be affected by saliva collagenase. The PH value gradually rises as a result of buffering of saliva, the activity of MMPs gradually increases making it able to hydrolyze matrix protein and which results in destruction of organic matrix.this causes caries.The Destruction of organic matrix that takes place in dental caries is a very complicated process. There are many different proteases that present within the oral cavity. Many scholars have focused their attention on a specific function of MMPs in the caries process. MMP inhibitor are also paid attention to by researchers.Studies found that bacteria themselves are not able to cause caries lesion, bacterial acids result in mineral matter removal and organic matrix imposition and host-derived MMP-8 activation.Our purpose in the experiment is to understand how does MMP-8 presents in tissue and what role does it play with the progress of caries. we therefore design our experiment whose major aim is to observe the presentation of MMP-8 in different carios teeth and investigate its function in the formation of caries. We hope our study will shed new light in the prevention and treatment of dental caries and present original avenues for prevention and cure of the same..Methods of data collection and analysis (Experimental Methods): we select extracted third molars which are not treated, as specimens for dental caries. According to clinical examination and radiography examination, they are divided into three groups that consists of enamel caries, superficial caries of dentin and deep caries. There are 10 cases in every group. We also select 10 cases of normal third molars teeth were also used as a control at the same time. HE stain and immunohistochemistry SABC are respectively used to examine expression of MMP-8 in different caries, while image analysis system is used for semi quantitative analysis.Experimental Results and Discussion: (1) HE stain shows: In normal group of molars, odontoblast in pulp tissue arrange paliform and dentinal tubule is regular, cell free zone is obvious, blood vessel do not stretch and there is no hyperemia. In enamel caries molar group, odontoblast in pulp tissue shows slight derangement, its layers increased and enamel texture can be seen, pulp tissue present network structure, and infiltration of inflamed cells was seen. In superficial caries of dentin group , odontoblast in pulp tissue shows slight derangement, image of dentinal tubule in dental caries zone is blur,layers increased fibroblast proliferate actively, cellular nucleus augment, cell free zone is not obvious, lymphocyte, granulocyte and macrophage exist in pulp tissue, blood vessel has slight hyperemia. In deep caries group, reparative dentin form under most carious lesion, Ancipital dentin cell-like cell is indiscriminate, which causes vacuolar degeneration, dentinal tubule is curved, blood vessel in the coronal pulp nearby carious lesion present lymphocytes and plasma cell that infiltrates, which activates hyperplasy.(2) Immunohistochemistry shows: In normal group,there is MMP-8 in odontoblast, predentine and fibroblast are slightlyn stained, other cells show no staining. In enamel caries group,expression of MMP-8 in odontoblast, predentine and fibroblast is weakly positive,while in other cells it is negative. In superficial caries of dentin, odontoblast proliferate actively, predentine become thicken, MMP-8 exhibits positive staining staining,staining of fibroblast become dark, immunity reaction of other cells is negative. In the deep caries group , fibroblast and odontoblast in pulp tissue are show positive expression, presentation of MMP-8 presenting within vascular endothelial cells ,surface of soften dentine and reparative dentin is strongly positive, expression of MMP-8 presenting within dentinal matrix is weakly positive .This study manifest that MMP-8 (a kind of endogenous protease) deriving from host and existing in carious lesion takes part in the caries progression process and also can be activated by bacteria, acid and protease present within carious lesion and degrades collagen fibers of dentine matrix in caries lesion, which influence proteolysis activity of MMP-8,also bring about different effect on caries process. It is summarized that MMP-8 participates in the caries process and development of MMP-8 inhibitors is capable of obstructing occurrence and development of caries.