| Objectives Three lining materials were selected in the experiment were SDR,Medental Flowable,Fuji Ⅸ glass ionomer cement.We compared the microleakage situation,shear bond strength of 3 kinds of lining materials according to use different etching adhesive systems,and the compressive strength and fluoride releasing.The purpose of this experiment is to provide some experimental evidences for clinical application.Methods 1 30 molars were randomly divided into five groups,which group has six teeth.The same size Class Ⅱ dental cavity were prepared in the near and far,and insured that the gingival wall ended above the CEJ 1mm.Group A: Kerr optibond versa selfetching adhesive,SDR cavity lining;Group B:Kerr optibond versa self-etching adhesive,Medental Flowable cavity lining;Group C: Acid etching,3M AdperTM Single Bond 2 total-etching adhesive,SDR cavity lining;Group D: Acid etching,3M AdperTM Single Bond 2 total-etching adhesive,Medental Flowable cavity lining;Group E:Fuji Ⅸ glass ionomer cement cavity lining,Kerr optibond versa self-etching adhesive.Then all groups were filled with 3M FiltekTM Z350-XT.After thermocycling,extracted five specimens that extracted from each group randomly were dyed with 2% methylene blue for 24 h.Use the dental operating microscoper to observe and photograph for classification and count.The remaining one specimen for SEM picture.2 50 molars were randomly divided into five groups,which group has ten teeth.The enamels of occlusal surfaces of these molar teeth were abraded and superficial dentine was exposed.Group F and G were bonded with Kerr optibond versa adhesive,Group H and I were bonded with 3M AdperTM Single Bond 2 adhesive,Group F and H were filled with SDR,Group G and I were filled with Medental Flowable,Group J was filled with Fuji Ⅸ glass ionomer cement without adhesive.All these 50 molars of five groups were prepared a certain size sample,then measured their shear bond strengths.3 30 columnar specimens in the same size of the three materials were prepared for compressive strength test.4 Three kinds of materials were made of 5 columnar specimens in the same size,and immersed into 12 ml deionized water at the temperature of 37℃.The release amount of fluorine ion in 3 kinds of lining materials was measured at 1,2,3,5,7,14,21,28,35 days with fluoride-specific ion electrode and acidometer.Results 1 The dye microleakage experiment:Observation under Rootmicroscope showed that the microleakage of Fuji Ⅸ glass ionomer cement was higher than other four groups,there was significant difference in five groups(P<0.005).The other four groups all had a good marginal sealing ability.There was no significant difference in these four groups(P>0.005).Observation under SEM showed that the dental tissues combined with materials dental closely which had a good marginal sealing ability in group A and C.Some cracks were found on the local in the group B and D,which had a ordinary marginal sealing ability.In the group E,the cracks between the materials and dental tissues was bigger than other groups,which had a poor marginal sealing ability.2 Shear bond strength test:The shear bond strength of Group F(9.10±2.04MPa)was the highest.The shear bond strength of Group G was(6.50±1.37)MPa.The shear bond strength of Group H was(6.25±1.09)MPa.The shear bond strength of Group I was(6.08±1.34)MPa,the shear bond strength of Group J was(3.91±0.76)MPa,which was the lowest one from all groups.The results of Kruskal-Wallis show that there was significant difference among five groups(χ2=30.354,P<0.05).Group F was higher than group G and group H group I and group J(P<0.005),There was no significant difference between group G and group H and group J(P>0.005),Group J was lower than the other four groups(P<0.005).3 Compressive strength test: The compressive strength of SDR was(206.72±12.20)MPa,the compressive strength of Medental Flowable was(161.88±11.94)MPa and the compressive strength of Fuji Ⅸ glass ionomer cement was(161.88±11.94)MPa.The results of one-way ANOVA showed that there was difference among three groups The compressive strength of the SDR is the highest,and the Fuji Ⅸ glass ionomer cement is the lowest,there was statistically significant difference in compressive strength among three materials(F=131.82,P<0.05).4 Fluoride release test:The highest fluoride release from Fuji Ⅸ glass ionomer cement and Medental Flowable were observed in the first day after immersion.The level of fluoride ion release from these two types of materials decreased rapidly in the second day,then the fluoride ion release leveled off.But the SDR maintained an invariable and low fluoride release between 1 to 35 days.Fluoride release from Fuji Ⅸ glass ionomer cement was higher than that from the beautiful dentist flow resin or the SDR in each period of time,there was statistically significant difference in fluoride release among three materials(P<0.05).Conclusions 1 Using the different etching adhesive systems,SDR and Medental Flowable all had good marginal sealing,when they were used as the posterior cavity liner in class Ⅱ.The group of Fuji Ⅸ glass ionomer cement had poor marginal sealing.2 On clinical,we recommend the use of Kerr optibond versa adhensive combined with SDR,because the shear bond strength and marginal sealing of this group was optimal.3 The compressive strength of SDR was the highest,the compressive strength of Medental Flowable was the second,the compressive strength of Fuji Ⅸ glass ionomer cement was the lowest.4 SDR,Medental Flowable and Fuji Ⅸ glass ionomer cement can release fluoride into the ambient liquid environment persistently in 35 days.Fuji Ⅸ glass ionomer cement had best ability of fluoride release.SDR had lowest ability of fluoride release. |
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