Effect Of PHEMA On The Activity Of MMPs In Human Dentin

Dental bonding technique is an important foundation of modern dental aesthetic and preservation restoration and the most active research fields in modern dentistry. However, dentin-resin bonding interface was still a weak link because of the particularity of the structure of dentin. It is common knowledge that HEMA is one of the main monomers of composite resin and glass ion hybrid dental materials, which can effectively penetrate into the internal hybrid layer and mediated dentin collagen and hydrophobic resin material combination that may prevent the degradation of collagen fibers in hybrid layer. Adhesive system containing HEMA can maintain the stability of bonding interface. But the monomer is unstable and toxic, precipitation of residual monomers can reduce the mechanical properties of restorative materials .Because of the existence of dentin tubule, dental pulp nerve endings are susceptible to the stimulation of residual monomers. The monomer HEMA can generate PHEMA by bulk polymerization, usually containing monomer and a small amount of initiator used in bulk polymerization, so the operation is simple and the product is pure, and PHEMA contains many hydroxyl groups on the side chain. While MMP is a kind of calcium and zinc dependent protease, its "zinc" structure is the key site of MMP activation. Oxygen in hydroxyl groups coordinates with divalent cation of MMP to form a coordination bond, the reversible inhibition of MMP is first formed, and then proton loss so that the formation of covalent bonds between them, which may cause irreversible inhibition of MMP. At present, the effect of PHEMA in dental adhesive on protease activity in dentin is rarely reported.Therefore, the monomer HEMA can generate PHEMA by bulk polymerization, the effect of PHEMA on MMP-2,8,9 in dentin was detected in this study, which can provide experimental evidence for the relationship between resin material and MMPs, meanwhile it can effectively prevent the degeneration of dentin bonding interface and provide theoretical basis for improving the durability of dentin resin bonding.Objective:The purpose of this study was to test the effect of poly (2-hydroxyethyl methacrylate) on the matrix metalloproteinase in dentin.Methods:HEMA was prepared into different contact area of PHEMA by Bulk polymerization, meanwhile normal human third molars were prepared into dentin powder and random grouping.The group without the treatment of PHEMA was used for control samples, and the other experimental groups were treated with different contact area of PHEMA, and extracting the dentin protein from the five groups. Under the same conditions, Extraction of dentin protein from PHEMA at the same contact area treated dentin powder at different times. The concentration of ICTP in the sample was analyzed by Cross-linked carboxyterminaltelopeptide type Ⅰ collagen reagent box, as well as the activity of MMP-2,8,9in dentin was detection by Zymography. Software of SPSS 17.0 was used for statistical analysis, ANOVA One-Way was used to analyze the effect of PHEMA on ICTP concentration in different contact areas. And LSD-t test for comparison between two groups. Image analysis is performed by using the gray level method.Results:PHEMA can inhibit the concentration of ICTP and the effect of inhibition was decreased by increasing time. PHEMA can inhibit the activity of MMP-2,8 and the effect of inhibition was increased by increasing the contact area, but the activity of MMP-9 was not significantly inhibited by PHEMA.Conclusion:1、The monomer HEMA can generate PHEMA under the action of catalyst and initiator and this method has the advantages of simple operation, pure product purity, low toxicity and high stability of the polymer.2、PHEMA can effectively inhibit the concentration of MMPs may effectively protect the degradation of type Ⅰ collagen during dentin adhesive or bonding operations, which can objectively maintain the stability of the resin-dentin bonding interface and improve the durability of dentin bonding.