Preparation And Performance Evaluation Of Cinnamaldehyde-containing Dentin Adhesive

Objective:At present,composite resin filling restoration is the main restoration method of tooth defect,and secondary caries is the main reason for restoration failure.In response to this problem,the development of a dentin adhesive with antibacterial function is an effective way to prevent the occurrence of secondary caries and prolong the service life of composite resin restorations.In this study,the plant-derived antibacterial agent cinnamaldehyde has been widely used in the food,cosmetics and medical and health industries because of its wide-spectrum antibacterial range,good antibacterial properties and high biological safety.This study first characterizes the antibacterial performance of cinnamaldehyde against oral cariogenic bacteria Streptococcus mutans,and then adds it to a commercial dentin adhesive in a certain proportion to prepare an antibacterial adhesive containing cinnamaldehyde to test the antibacterial properties of the adhesive It also discusses the effect of the addition of cinnamaldehyde on the in vitro cytotoxicity and bonding performance of the adhesive,comprehensively evaluates the performance of the cinnamaldehyde dentin adhesive,and provides an experimental basis and ideas for the development and application of antibacterial adhesives.Methods:1.Measure the MIC and MBC of cinnamaldehyde against Streptococcus mutans by the micro broth dilution method.2.With the commercial adhesive Single Bond 2 as the control group,cinnamaldehyde was added to the commercial adhesive Single Bond 2 in the proportions(wt%)of 2%,4%,6%,and 8%,and mixed uniformly to prepare the test pieces.Co-cultivation of specimens and bacteria,plate colony counting method to determine the number of bacteria attached to the surface of the material and calculate the antibacterial rate;draw the growth curve of the co-culture specimens indicating the adhered bacteria;conduct live/dead staining experiments on the bacteria on the surface of the co-cultured specimens,Directly observe the state of bacteria attached to the surface of the specimen.3.Prepare the extract of the test piece,and determine the in vitro cytotoxicity of the adhesive by the MTT method.4.On this basis,select the experimental group with significant antibacterial properties to test the water contact angle and double bond conversion rate of the adhesive,and use the micro-tensile test to determine the immediate bonding strength of the adhesive.Results:1.The MIC and MBC of cinnamaldehyde for Streptococcus mutans are both250 μg/ml.2.In the bacterial adhesion colony count experiment,for Streptococcus mutans,the antibacterial rate of the adhesive was higher than 99% when the cinnamaldehyde content was 4wt% and above,indicating that the adhesive has significant antibacterial performance;the growth curves of the two bacteria show that as the content of the antibacterial agent cinnamaldehyde increases,the bacterial suspension at the same time point The decrease in absorbance value(OD)indicates that the bacterial density decreases with the increase of cinnamaldehyde,and the inhibition of bacterial growth by the material is concentration-dependent;in the bacteria live/dead staining experiment,with the gradual increase of the cinnamaldehyde content in the adhesive High,the total amount of bacteria attached to the surface of the specimen and the number of viable bacteria are significantly reduced.3.In the in vitro cytotoxicity experiment,the cell survival rate of each group was higher than 70%.Under the same dilution ratio,compared with the control group,the cytotoxicity level of the antimicrobial adhesive did not increase.4.In the bonding performance testing experiment,the 4wt% and above groups were selected for the experiment,and the water contact angle,double bond conversion rate and micro-tensile strength of each experimental group were not significantly different from those of the control group(р﹥0.05).Conclusion:Cinnamaldehyde has good antibacterial properties.When the content of cinnamaldehyde is 4wt%,the antibacterial adhesive has significant antibacterial properties,and its in vitro cytotoxicity and adhesion properties are not significantly affected.4wt% is the best addition ratio of cinnamaldehyde in the adhesive,which can provide good overall performance for the antibacterial adhesive.