Research On Interlayer Tightness Of New And Old Light-cured Composite Resins

Objective（s）:（1）To study the effect of different surface treatment methods between layers on the interlayer tightness during the layered curing of resin filling in deep and large cavities;（2）To study the change of interlayer tightness after treating the surface of aged resin in different ways and filling with the same resin;（3）It is expected to optimize the operation of resin filling and resin filling and retreatment in clinical deep and large cavities,and improve the efficiency and treatment success rate.Methods:Filtek^TMZ350A2 composite resin,Adper ^TMEasy One self-etching adhesive system and Adper^TMSingle Bond 2 all-etching adhesive system were selected as the materials.90 resin blocks of 4mm×4mm×2mm were prepared from external silicon rubber abrasives.45 samples were randomly selected and stored in distilled water at 37℃for 2 months.The other 45 samples are used as a routine experimental group（N）,each group is divided into 3groups according to different surface treatment methods,totaling 6 groups,each group has15 samples,the abbreviations of each experimental group are replaced by letters,Y represents aging experimental group,N represents the routine experimental group,O represents no adhesive,E represents Easy One self-etching adhesive,and S represents Single Bond 2 full-etching adhesive.NO group:Routine+No surface treatment;NS group:General+Single Bond 2;NE group:General+Easy One;YO group:Aging+320 mesh sanding:YS Group:Aging+sandpaper+Single Bond 2:YE group:Aging+sandpaper polishing+Easy One.After surface treatment of the above samples according to respective requirements,2mm of the same resin is filled in layers.After filling,all samples are stored in37℃distilled water for 24 hours,and then according to ISO/ST11405 standard.performing500 times of cold and hot temperature cycling,then using 1%methylene blue to dye for 24hours,using a slow mobile phone to vertically cut the middle of the adhesive layer to be observed,forming two sections respectively,observing the leakage condition under a stereo microscope,The maximum score is taken as the final stain value of the sample.The statistical analysis was carried out by SPSS24.0 software,Fisher exact probability method was adopted between two samples of the two groups of experiments,and the test level was P=0.05.Results:The results of the type microscope showed that（1）in the conventional experimental group,there was no microleakage in direct filling（NO group）,and there was microleakage in the use of adhesives（NE group,NS group）,but no statistics compared with the direct filling group Academic difference（P>0.05）;（2）Aging experimental group:microleakage existed in all groups,but there was no statistical difference compared with direct backfill group（NO group）,and there was no statistical difference in microleakage among all groups（P>0.05）.Conclusion（s）:（1）Fresh resin layered filling has good interlayer sealing,and the adhesive does not affect the interlayer sealing;（2）After the surface of the aged resin is polished,it can be directly refilled or coated with adhesive.Whether it is one-step self-etching adhesive Easy One or two-step all-etching adhesive Single Bond2,the sealing between the new and old resin layers is good.