Composition Adjusting And Antibacterial Properties Of Self-etching Adhesives

The adhesive is a liquid material used in conjunction with dental composite resin.The self-etching adhesive itself is acidic,which reduces the phosphoric acid etching step in the repair process,and relies on the polymerizable acidic functional monomer in its composition to complete the acid etching.The dissolved smear layer of acid solution,the permeable resin monomer and the adhesive infiltrated into the collagen fiber mesh formed a mixed layer.After curing,the composite resin was combined with the subsequent operation to achieve the purpose of bonding and repairing.At present,there is still no adhesives that can completely seal the adhesive layer to avoid microleakage,and microleakage is easy to cause bacteria breeding and secondary caries cause repair failure.It is important for practical application to regulate the composition of self-etching binder,improve its adhesive property and endow it with antibacterial property.In this paper,bisphenol A glycidyl methacrylate?Bis-GMAA??dilute monomers triethylene glycol dimethacrylate?TEGDMA?and 2-hydroxyethyl methacrylate?HEMA?were used as the experimental resin matrix to prepare a self-etching binder and its properties were studied.The adhesion strength of monomer mixture and the effect of acid functional monomer on pH value and curing depth of adhesives were studied by means of micro-tensile test method to determine the content of several main monomers in the adhesive step by step.The optimum formula of the adhesive prepared is as follows:Bis-GMA/TEGDMA=3:2?mol?;HEMA 5 wt%;CQ 0.2 wt%;4-EDMAB 1.6 wt%;10-MDP 5 wt%;inorganic filler SiO₂?OX-50?5wt%.The prepared adhesive has a micro-stretch bond strength of 25.3±2.36 MPa,a compressive strength of 296±14.4 MPa,and an antimicrobial activity of up to 68%?against Streptococcus mutans?.In order to improve the antibacterial effect of the adhesive,the folded mesoporous silica loaded nano-silver?SiO₂@Ag?antibacterial agent was prepared.The mesoporous agent can limit Ag to below 10nm,reduce the amount of silver and improve the antibacterial properties.The composition of the adhesive prepared is as follows:BisGMA/TEGDMA=3:2?mol?;HEMA 5wt%;CQ 0.2 wt%;4-EDMAB 1.6 wt%;10-MDP 5 wt%,inorganic filler SiO₂@Ag 0.1 wt%.The prepared adhesive has a micro-stretch bond strength of 27.5±2.38 MPa,a compressive strength of203±16.2 MPa,and an antimicrobial activity of up to 99%?against Streptococcus mutans?.