Effect Of 4-formylphenyl Acrylate Primer On Dentine Self-etching Bonding

Objective:The objective was to prove the ability of 4-formyl phenyl acrylate(FA)primer to improve the bond durability of universal adhesives in self-etching mode,and to investigate the effect of FA primer on the inhibition the activity of matrix metalloproteinases(MMPs)in dentin by in situ zymography.Methods:The experimental groups with different concentrations of FA primer(1wt%,3 wt%,5 wt%,7 wt%,9 wt%)were prepared,and two commercial universal adhesives:Single Bond Universal(SBU)/All-bond Universal(ABU)were selected as control groups.Firstly,the cytotoxicity and the degree of conversion were tested to screen the optimal concentration.Then,in light of the pre-treatment time(30 s,1 min,and 2 min),the micro-tensile bond strength was evaluated by the storage in deionized water for 24 hours(immediate)and thermocycling for 10,000 cycles(aging).The contact angle and atomic force microscopy were used as auxiliary test methods to screen out the best concentration of action.Finally,nanoleakage test was used to evaluate the silver staining of the bonding interface of different groups before and after aging.In situ zymography was used to detect the collagenase activity of the hybrid layer and laser confocal test was used to observe the adhesive interface.Results:1.The results of cytotoxicity and the degree of conversion showed that 5 wt%FA primer not only ensured the conversion rate of adhesive,but also controlled the relative cell viability at 80%;2.According to the micro-tensile strength before and after aging,it can be seen that in the 1-min group of FA primer pretreatment,the micro-tensile strength of the aging group was similar to the immediate value,while the other groups all decreased to varying degrees.In addition,the results of water contact Angle and atomic force microscopy also confirmed that 1 minute was the best time of FA primer;3.The nanoleakage expression of the samples with FA primer(5 wt%)applied for 1 min after aging did not change significantly compared with their immediate values;The results of in situ zymography showed that the endogenous proteolytic activity was significantly decreased after FA pre-treatment.Confocal laser scanning microscopy(CLSM)demonstrated the effect of FA primer on micropermeability at the resin-dentin interface.Conclusion:FA primer applied to dentin by self-etch bonding system can covalently bond adhesives to collagen matrix,thus making up for the disadvantage of chemical bonding of commercial adhesives to collagen.FA primer at 5 wt%concentration for 1 min can improve the permeability and invasiveness of the adhesive,thereby enhancing the integrity of the dentin-resin interface,inhibiting the activity of endogenous MMPs.