| Purpose:To evaluate and discuss the effect of preheating on the monomer conversion and polymerization volume shrinkage of SonicFill Bulk-fill resin,and compare the difference of curing performance between SonicFill resin and traditional Z350 resin,so as to provide some reference for clinical application of SonicFill resin.Methods:1.Grouping and preheating of resin samples40 samples of SonicFill resin were randomly selected and divided into monomer conversion group(DC group)and polymerization volume shrinkage group(PVS group).The DC experimental group was further divided into two subgroups:one subgroup was preheated to(55±5)℃ for 15 min,and then the monomer conversion was determined;the other subgroup was at standard room temperature(23 ± 5)℃ for 15 min,and then the monomer conversion was determined.PVS experimental group was also divided into two subgroups:preheating and room temperature,and the corresponding polymerization volume shrinkage was measured.Then 40 Z350 resin samples were randomly selected for the same grouping treatment and experimental determination as the above SonicFill resin samples.According to the type of resin test,resin type and preheating,the samples were divided into the following 8 groups(n=10):(1)The group of the Monomer Conversion experiment:Group ADC:no preheating,SonicFill resin groupGroup aDC:preheating,SonicFill resin groupGroup BDC:no preheating,Z350 resin groupGroup bDC:preheating,Z350 resin group(2)The group of the Polymerization Volume Shrinkage experiment:Group AOVS:no preheating,SonicFill resin groupGroup aPVS:preheating,SonicFill resin groupGroup BPVS:no preheating,Z350 resin groupGroup bPVS:preheating,Z350 resin group2.Determination of Double bond ConversionNicoletTM is50 FTIR spectrometer was used to record the monomer conversion of SonicFill and Z350 resin.The absorbance of resin samples in the experimental group before and after curing was recorded.Infrared spectrum wavenumber range:4000-400cm-1,resolution:4cm-1,scanning times:4,ambient temperature:23±5℃,relative humidity 34±1%.The spectral absorption intensity of each point can be directly given by the machine.The standard baseline technology is adopted,and the absorption intensity of the aromatic reference peak(the bond peak is located at 1608-1)which remains unchanged during the polymerization process is taken as the internal standard,the percentage of residual unreacted C=C in the curing reaction of resin sample was calculated by measuring the change of the C=C absorption peak(bond peak at 1638-1)before and after polymerization.C=C(%)=Rcured/Runcured.Among them,Rcured is the ratio of the absorption intensity of aliphatic C=C absorption peak at wave number 1638cm-1 and aromatic reference peak at wave number 1608cm-1.Runcured is the ratio of the absorption intensity of aliphatic C=C absorption peak at wave number 1638cm-1 to aromatic reference peak at wave number 1608cm-1 before curing.Then subtract C=C(%)from 100%to get the monomer conversion of resin sample.3.Determination of Polymerization Volume ShrinkageBased on the laser ranging technology,the LK-G30 laser displacement sensor is used.The resolution is 0.01 U m,the overall dimension of the resin specimen is 4mm long and the cross-sectional dimension is 4mm × 4mm.The dynamic shrinkage of resin samples in the experimental group was monitored in real time during the curing process,and the linear shrinkage was measured and recorded as lin%.The PVS%=31in%-0.03(lin%)2+0.0001(lin%)3 was calculated according to the formula,and the linear shrinkage was converted into volume shrinkage.According to the measured data,the volume shrinkage time curves of SonicFill and Z350 resins were drawn,and change of volume shrinkage of two resins,which truly reflected the whole process of resin free polymerization shrinkage under the influence of preheating.5.Statistical treatmentThe results were statistically analyzed using SPSS22.0 software.Two-Way ANOVA and Group comparison test was used for the monomer conversion rate and polymerization volume shrinkage rate between different resin sample groups,and the monomer conversion rate and polymerization volume shrinkage rate of the same resin sample whether it was preheated or not.P<0.05 was considered to be statistically significant.Results:1.Curing property of the same resin sample before and after preheating:(1)Monomer Conversion:group aDC>group ADC,group bDC>group BDC,P<0.05,the difference was statistically significant;(2)Polymerization Volume Shrinkage:group APVS>group apvs,group BPVS>group bpvs,P<0.05,the difference was statistically significant.2.Curing properties of two kinds of resin samples in unheated group:(1)Monomer Conversion:group ADC>group BDC,P<0.05,the difference was statistically significant;(2)Polymerization Volume Shrinkage:group BPVS>group APVS,P<0.05,the difference was statistically significant.3.Curing properties of two kinds of resin samples in unheated group:(1)Monomer Conversion:group aDC>group bDC,P<0.05,the difference was statistically significant;(2)Polymerization Volume Shrinkage:group bpvs>group apvs,P<0.05,the difference was statistically significant.Conclusion:1.Under the conditions of this experiment,the Monomer Conversion and Polymerization Volume Shrinkage properties of SonicFill Bulk-Fill resin are obviously better than those of Z350 composite resin.2.Preheating can significantly improve the Monomer Conversion of SonicFill and Z350,and significantly reduce the Polymerization Volume Shrinkage of SonicFill and Z350. |
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