Surface Modification Of New Inorganic Fillers And Properties Of Self-etching Adhesive

Dental adhesive is used to repair resin material support,which is applied to several decades of history of dental restoration areas,and in recent years its overall performance has been greatly improved.However,with the emergence of self-etching adhesives,it is widely welcomed by doctors and patients because of its simple operation and suppression of postoperative sensitivity.Different from the full acid-etching bonding system,the self-etching bonding system relies on its own acidic ingredients to dissolve the stain layer on the teeth surface,so as to achieve the purpose of penetrating into the dentin tubules and covering the surface.Because there is no phosphoric acid corrosion,it retains more healthy tooth tissue to a certain extent,so the irritation to dental pulp is greatly reduced.The presence of the adhesive enhances the interface between teeth and resin,which can effectively alleviate the microleakage and secondary dental caries caused by the polymerization shrinkage of the restoration material.However,the bonding strength between the interface and teeth or resin can not be completely closed by adhesive,and further improving the bonding strength of adhesive is widely concerned in clinical applications.This paper mainly uses bonded Zr O₂,Si C,BN as inorganic fillers to enhance the comprehensive performance of the self-etching adhesive.The main results obtained are as follows:（1）A layer of silicon dioxide（Si O₂）was coated on the surface of zirconia（Zr O₂）by the sol-gel method to prepare Zr O₂@Si O₂,and then Zr O₂@Si O₂was modified with a silane coupling agent.The modified Zr O₂@Si O₂was filled into the matrix of self-etching adhesive in a proportion of 1 wt.%,2 wt.%,5 wt.%and 10 wt.%,and the influence of different filling amounts on the mechanical properties of the adhesive was studied.The mechanical test results showed that when the inorganic filler content was 2 wt.%,the bonding strength was the highest,its31.63±1.53 MPa,which was 78.8%higher than the control group.When the packing content was 1 wt.%,the compressive strength reached the highest,which was 242.1±38.3 MPa,an increase of 17.5%compared with the control group,and the compression strength was basically maintained at 2 wt.%.In addition,the slice characterization of the bonded samples showed that the presence of adhesive significantly reduced the gap between restoration and teeth,reducing the occurrence of postoperative microleakage effectively.（2）The silicon carbide（Si C）whisker with a length of 10～50μm was selected as an inorganic filler,and the Si C whisker was modified with silane coupling agent.The effect of the modified Si C whisker on the mechanical properties of self-etch adhesive was studied by filling the modified Si C whisker with different mass fractions,and the properties were compared with commercial adhesive 3M/ESPE.The results showed that the bonding strength was the highest（36.71±1.92 MPa）when the filler packing content was 0.3 wt.%,which was 107.6%higher than the experimental group without filler.The bonding strength and compression strength of commercial adhesive 3M/ESPE were 16.29±3.13 MPa and 67.92±16.16 MPa respectively.The performance of experimental group adhesive is better than commercial adhesive.The section test of the bonded sample also showed that the adhesive group with high bonding strength has a better sealing effect on dentin tubules and prevention of microleakage.（3）First,the boron nitride（BN）surface was coated with Si O₂by the sol-gel method to prepare BN@Si O₂,and the Si O₂coating thickness was controlled by regulating the amount of tetraethyl orthosilicate（TEOS）,which was respectively 10 nm（A1）and 3 nm（A2）.Then the silane coupling agent was used to modify BN@Si O₂.The modified BN@Si O₂was filled into the self-etching adhesive with different mass fractions,and the influence of filling amount and silicon dioxide coating thickness on the mechanical properties of adhesive was studied.It can be seen from the test results that both groups showed best bonding strength when the filler content is 0.5 wt.%,and the mechanical properties began to decline when packing content increased.The maximum bonding strength of Group A1 was 28.18±1.90 MPa,which was increased by 48.2%compared with the control group;the maximum bonding strength of group A2 was 32.48±1.73MPa,which was increased by 70.9%compared with the control group.It can be seen that the mechanical properties of the silicon dioxide coating on the surface of BN are better when it is 3nm.A group with better mechanical properties was selected to introduce silver antibacterial particles to prepare BN@Si O₂@Ag.According to the antibacterial test results,the antibacterial rate was 89%before addition of antibacterial particles,and the antibacterial rate was≥99.9%after addition.The results showed that the silver particles haves good antibacterial property.