| Objectives To observe the effects of different treatment methods on edge microleakage,scanning electron microscope observation and shear bonding strength by respectively treating dental erosion enamel with infiltration resin and fluoride agent and then performing flowing resin bonding,so as to provide experimental basis for selecting an ideal treatment method for enamel bonding of dental erosion in clinic.Methods Sixty intact isolated teeth were taken,which required complete teeth,no caries and no cracks.The surrounding soft tissues were removed,dental plaque and tartar on the tooth surface were removed with ultrasonic dental cleaner,cleaned with physiological saline,soaked in 100 ml Coca-Cola(p H=2.58),demineralized for 5 minutes,rinsed with deionized water after 5 minutes,stored in artificial saliva at a constant temperature of 37?,and demineralized 10 times within 12 hours per day for 7 days to form an artificial enamel demineralization model.The 60 extracted teeth after demineralization and acid etching were randomly divided into three groups: Infiltration Resin Group: The tooth surface was dried after conventional cleaning,and adhere the tooth surface with conventional flowing resin after resin infiltration treatment;Fluoride Agent Group: The tooth surface was dried after conventional cleaning,apply fluorinating agent for 5 minutes,then rinsed with clear water.Then the tooth surface was dried again and performed conventional flowing resin bonding;Control Group: The tooth was conventionally bonded with flowing resin with out any treatment.1.microleakage experiment: 10 isolated tooth samples were taken from each group.The samples were soaked in methylene blue solution at 37 ? for 24 h,acetone was used to remove nail polish,running water was used to thoroughly clean the residual dye on the tooth surface,and the samples were stored in distilled water at 4 ?for later use.Slice: Using emery low-speed saw to slice specimens along the buccal and lingual surfaces at 3 points corresponding to the medial-distal middle fossa and the midpoint of the connecting line,6 sections were obtained.Using a single blind method,two examiners who had previously undergone the standard consistency test evaluated the staining penetration of flowing resin and enamel under a stereomicroscope.Each evaluator separately evaluated the dye leakage at the incision of the lateral two pieces and the midpoint of each sample.Each filling body was scored four times by two evaluators,and the highest score of the four scores of each filling body was recorded and statistically analyzed.The severity of staining was analyzed with a scoring system of 0-2 grades:Grade 0: no dye infiltrated into the interface between flowing resin and enamel;Grade 1:The depth of dye penetration into the interface between flowing resin and enamel is less than or equal to 500?m;Grade 2: The depth of dye penetration into the interface between flowing resin and enamel is more than 500 m.2.Scanning electron microscope experiment:2 teeth were taken from each group and cut into slices.Emery was used to slice the tooth along the buccal-tongue direction at a low speed,800 mesh silicon carbide sandpaper was used to grind and polish,ultrasonic cleaning was performed,10% hydrochloric acid was soaked for 1min,washing and drying were completed.The samples were fixed on the sample table,vacuum-pumped and gold-sprayed for coating,and the morphology of the material-enamel interface was observed by scanning electron microscopy at 1000 and 2000 times magnification,respectively.3.Shear strength test: 8 samples of isolated teeth were taken from each group.Crown was cut from the neck of the isolated teeth.The cut crown was embedded in self-setting resin to expose the treated isolated enamel surface to about 5mm× 5 mm.The prepared cylindrical mold(3mm in inner diameter and 3mm in height) was vertically placed on the polished enamel surface and the edge was sealed with wax.The flowing resin was added to the three sets of molds in layers,and each layer was visible for 40 seconds.After curing was completed,the mold was removed and a 3mm diameter and 3mm high flowing resin cylinder was formed on each enamel surface to test the shear bond strength.All specimens were placed in 37 ? water bath for 24 h,then immersed in 0-5?water bath and 50-55 ? water bath respectively for 500 temperature cycles,each temperature stayed for 15s(according to ISO-TR11405).The test piece is fixed in a self-made fixture,and the experimental cutter head is connected with a DZS-III hard and brittle material performance detector.Make the cutter head 0.5mm from the bonding surface of the sample and make the loading direction parallel to the bonding surface.The loading speed is 0.5 mm/min until the pit and fissure sealant small column and tooth surface are broken.The computer connected with the detector automatically displays the load value and stress value and records the maximum shear stress value.Calculate the shear bond strength according to the formula.4.Statistical analysis: The experimental data were statistically analyzed using SPSS23.0 software.The results of shear bond strength were compared by one-way ANOVA.The LSD-t method was used for comparison,test level ? =0.05,P<0.05 was statistically significant;Edge microleakage test results using rank sum test,three groups were compared with Kruskal-Waills,test level? = 0.05,P <0.05 was statistically significant.Results 1.Microleakage experiment: the three groups of edges were sealed well under stereomicroscope,no dye microleakage was observed at the bonding interface.The flowing resin was tightly bonded to the enamel surface,and no obvious gap was found.The dye was only confined to the flowing resin surface,and no dye penetrated into the bonding interface.There was no significant difference in microleakage among the groups(P>0.05).2.Scanning electron microscope observation: The bonding material of Infiltration Resin Group bonding interface is closely bonded with tooth tissue,with good edge sealing,and can form clear,long and dense resin protrusion.In Fluoride Agent Group,the bonding material of the bonding interface has poor bonding with tooth tissue,the cracks between the material and enamel were wide and rough,and resin protrusion cannot be found between the bonding material and the tooth surface.The bonding material at the bonding interface of Control Group is tightly bonded to the dental tissue,with good edge sealing,and resin protrusion can be formed but resin protrusion is short and sparse.3.Shear strength: Infiltration Resin Group has the highest shear bond strength(10.92 ±1.80)MPa,Control Group has the second shear bond strength(2.52 ± 0.19)MPa,and Fluoride Agent Group has the lowest shear bond strength(0.89±0.14)MPa.The results of one-way ANOVA showed that the differences among the three groups were statistically significant(F=370.29,P<0.001).The comparison between the two groups showed that Infiltration Resin Group was higher than the other two groups(P<0.05).Control Grou was higher than Fluoride Agent Group(P<0.05)and Fluoride Agent Group has the lowest shear bond strength.Conclusions 1.After the treatment with infiltration resin and fluorinating agent,the flowing resin bonding and enamel surface can form good edge sealing.2.Infiltration resin treatment to dental erosion enamel can lead to long and dense resin bumps,while fluoride treatment has poor bonding with resin materials without resin bumps.3.The shear bond strength with flowing resin is better in infiltration resin than that in fluoride group.4.Infiltration resin treatment is better than fluoride treatment and untreated groups in edge microleakage,SEM observation and shear bonding strength,and is the preferred method for enamel bonding pretreatment to dental erosion.Figure 13;Table2;Reference 93... |
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