Influence Of Thickness Of E.max CAD Glass-ceramic And Light-curing Mode On Polymerization Degree Of Rely X U200

ObjectiveIn this study,Fourier transform attenuated total reflection infrared spectroscopy(ATR-FTIR)was used to analyze the degree of polymerization of self-adhesive dual-curing resin cement 3M RelyX U200 under different thickness of E.max CAD glass-ceramic and different light-curing modes.This study provides some reference for clinical resin bonding operation.MethodsExperiment 1: The resin cement RelyX U200 was filled in DSC alumina crucible(6.5mm in diameter and 1.5mm in height)to prepare 50 pieces of test pieces.The Elipar S10 LED light curing lamps were randomly selected for traditional light 20s(TR)and prolonged light 40s(PR),each light pattern was divided into four experimental groups H1,H2,H3,H4(E.max CAD HT A3 tiles 1mm ~ 4mm thick)and one control group H0(coverslip)according to the thickness of the medium.In total,there are 10 groups,each group of 5 specimens.The infrared spectra of RelyX U200 before and after curing were recorded by Fourier transform attenuated total reflection infrared spectroscopy(ATR-FTIR).The degree of conversion(DC)of resin cement was calculated.The statistical data were analyzed by two-way ANOVA.Experiment 2: The resin cement RelyX U200 was filled in DSC alumina crucible(diameter 6.5mm,height 1.5mm).25 specimens were randomly divided into 5 groups: experimental groups IN1,IN2,IN3,IN4 and control group TR.Elipar S10 LED light cured specimens with different modes,IN1(light 2s + intermittent 30 s + light 20s),IN2(light 2s + intermittent 60 s + light 20s),IN3(light 2s + intermittent 90 s + light 20s),IN4(light 2s + intermittent 120 s + light 20s)and TR(light 20s)are accepted by E.max CAD HT A3 tiles(thickness 1mm).The infrared spectra of RelyX U200 before and after curing were recorded by Fourier transform attenuated total reflectance infrared spectroscopy(ATR-FTIR),and the degree of polymerization conversion(DC)was calculated.The statistical data were analyzed by one-way ANOVA,LSD-T test and Student's T test.Results1.With the increase of the thickness of E.max CAD glass-ceramic,both in the traditional light pattern(TR)and the extended light pattern(PR),RelyX U200 DC% decreased significantly(P<0.05).The DC% of TR group decreased from 35.46%(TRH0)to 12.22%(TRH4),while the PR group decreased from 39.24%(PRH0)to 21.41%(PRH4).In the same tile thickness,the DC% of prolonged light group is higher than the traditional light group(P<0.05).2.The intermittent light-curing mode RelyX U200 DC% were significantly higher than the traditional light-curing mode(P<0.05).With the prolongation of intermittent time(within 2 min),DC% gradually increased from 30.32%(IN1)to 37.04%(IN4).Differences between groups were statistically significant(P<0.05).Conclusion1.With the increase of the thickness of E.max CAD glass-ceramic,the degree of polymerization of RelyX U200 decreased,while the prolonged light-curing mode could promote the degree of polymerization.2.The degree of polymerization of RelyX U200 in the intermittent light-curing mode is higher than traditional light-curing mode,which increases with increasing interval time in 2min.