The Study Of Aging And Bacterial Adhesion Of Bulk-fill Resin

ObjectivesTo compare the color stability,water absorption and solubility,edge microleakage and bacterial adhesion of bulk-fill Smart Dentin Replacement（SDR）,3M ESPE Filtek Bulk Fill（FBF）,TetricN-Ceram Bulk Fill（TEBF）,X-tra fil（XT）and traditional composite resin 3M ESPE Filtek Z350（Z350）and provide experimental evidence for clinical application.Methods1 Color stability test of bulk-fill resin:SDR,FBF,TEBF,XT and Z350 resins were selected.The cylindrical mold with an inner diameter of 6mm and a height of 4mm was prepared,the mold was placed on a glass plate,the resin was separately filled into a mold and compacted with a glass slide.The light curing lamp was irradiated for 20 seconds to cure the test piece,and taken out it.The water sandpaper was used to grind the test piece and polished,and the surface roughness value（Ra）of the resin test piece was tested until there was no statistical difference in the roughness between the test pieces.The original color of the resin test piece was tested using a computer colorimeter.Then,each set of resin test pieces was separately immersed in artificial saliva,and stored in a constant temperature water bath of 60±1℃in the dark.The test pieces were taken out at the first,second,third,and fourth weeks,and the chromaticity values of the test pieces were measured again and recorded.The color change value of each test piece was calculated according to the color difference formula.2 Water absorption and solubility test of bulk-fill resin:The test piece was made in the same way as experiment 1.The prepared test piece was placed in an incubator（37℃）and dried,and the mass was weighed daily until the weight was constant as M₁.The diameter and thickness of the test piece were measured,and the volume V was calculated.Then,the test piece was immersed in a test tube containing distilled water for 4 weeks,and after 4 weeks,the test piece was taken out,and the surface moisture of the test piece was blotted with an absorbent paper,and the weight was again weighed as M₂.The test piece was then replaced in an incubator again,weighed daily,and the measurement was repeated until a constant weight M₃ was obtained.The dissolution value and water absorption value of various resins were calculated according to the formula.3 Bulk-fill resin edge micro-leakage experiment:50 collected third molars were randomly divided into 5 groups,10 in each group,and a certain type of Class I hole was prepared.The cavity was disinfected and used.Resin filling after two-step acid etching:SDR,FBF,TEBF,XT single filling,Z350 resin layered filling,solidified and polished.The prepared sample to be tested is subjected to hot and cold circulation,and then the test piece is taken out,dried at room temperature,and the apical tube of the apical hole is closed by dipping wax,and the nail polish is sealed except for the filling portion,and immersed in 1%methylene blue staining solution.In the middle 24h,the slice was taken along the buccal tongue,and the edge microleakage was observed under a stereo microscope.4 Bulk-fill resin bacterial adhesion test:The test piece was made in the same way as experiment 1,preparation of brain heart infusion Broth（BHI）liquid and solid medium,Streptococcus mutans strain recovery and passage,preparation of bacterial suspension,20μl of bacterial solution inoculated in BHI solid medium,anaerobic culture for 48h at 37A single colony was placed in a liquid medium and cultured in an anaerobic culture at 37℃for 48 h.Dilute in PBS,adjust the bacterial concentration by spectrophotometer,store in a refrigerator at 4℃,and set aside.All the tested parts were ultrasonically cleaned,and the front and back sides were irradiated under ultraviolet light for 4 hours.The test piece was immersed in the prepared bacterial suspension,anaerobic cultured at 37℃for 48 hours,rinsed with PBS,and placed in sterile liquid medium.The medium was sonicated,the bacterial solution was diluted 10-fold,and the plate was coated.The anaerobic culture was carried out at 37℃for 48 hours,and the colony was counted.The data of each test were analyzed statistically.Results 1 Color stability test of bulk-fill resin:statistical analysis of color difference measured by different materials in artificial saliva soaking environment at different times.After 4 weeks,the color difference between materials was different,XTΔE（2.97±0.064）was smaller than the other four groups（P<0.05）.There was no significant difference between SDR and FBF（P>0.05）.There was no significant difference between TEBF and Z350（P>0.05）.2 Water absorption and solubility test of bulk-fill resin:The water absorption values of the five groups of materials were SDR,Z350,FBF,TEBF,XT.There was no significant difference between FBF and TEBF and Z350（P>0.05）.There was significant difference between the other groups（P<0.05）.The dissolution value of XT[（-0.21±0.28）μg/m³]was lower than that of the other four groups,the difference was statistically significant（P<0.05）,and the difference between the other four groups was not statistically significant（P>0.05）.3 Micro-leakage test of bulk-fill resin:Five groups of resin specimens have edge micro-leakage,but the difference is not statistically significant（c²=8.089,P>0.05）,The difference of FBF,XT and Z350 was statistically significant（P<0.05）,and the difference between the other groups was not statistically significant（P>0.05）.4 Bacterial adhesion test of bulk filling resin:The bacterial adhesion of the five groups of resin samples was at least XT,SDR,Z350,TEBF and FBF,and there was no significant difference between the two groups（TEBF and Z350）（P>0.05）,the difference between the other groups was statistically significant（P<0.05）.Conclusions 1 In the color stability study,the color change of low viscosity bulk-fill resin（SDR,FBF）is greater than that of traditional nanocomposite resin（Z350）and high viscosity bulk-fill resin（TEBF,XT）.2 In the comparative study of water absorption and solubility,the water absorption of low viscosity bulk-fill resin（SDR,FBF）is greater than that of traditional composite resin（Z350）and high viscosity bulk-fill resin（TEBF,XT）,and the XT dissolution value is the smallest.It is superior to the other three bulk-fill resins（SDR,FBF and TEBF）and traditional composite resin（Z350）.3 In the study of edge microleakage,the edges of the five composite resins are well sealed,but the occurrence of edge microleakage cannot be avoided.4 In the bacterial adhesion study,the bulk-fill resin FBF bacteria had the least amount of adhesion,which was superior to the other three bulk-fill resins（SDR,TEBF and XT）and traditional composite resin（Z350）.Figure18,Table9,Reference 156.