The Influence Of Different Time On The Bond Strength Of Fiber Posts With Different Surface Treatment And Different Kinds Of Resin Adhesive Systems

Objectives:The purpose of this in vitro study was to evaluate the influence of different time on the push-out bond strength of glass fiber posts with four kinds of surface treatment methods and three different kinds of resin adhesive systems in 37℃ artificial saliva.And if the glass fiber posts bond strength in different root canal depths is different,providing some experimental basis for clinical doctors to choose the proper resin adhesive system and the surface treatment method.Materials and Methods:The freshly extracted first premolar of mandibular with single root canal was selected as experimental objects.Statistical analysis was used to confirm that there was no statistical difference among the teeth.Cut off the crown above the cement and enamel junction 2mm and then endodontically treated with the standard procedures,followed by preparation of the space of fiber post.They were used for two experiments.Test One: Forty Five freshly extracted first premolar of mandibular with single root canal were divided into 3groups(n=15)with endodontically treated.The fiberposts were cemented with three resin cement systems:(group A)total-etch adhesive system;(group B)self-etch adhesive system;(group C)self-adhesive system.Each group was divided into 3 subgroups(n=5)for no soaking(A1,B1,C1),soaking in37℃ artificial saliva for 24 hours(A2,B2,C2)and 6 months(A3、B3、C3).Each root was sectioned perpendicularly to its long axis to create 6 specimens of thin slices with 1-mm thickness for a push-out bond strength test.The specimens were divided into upper,middle,and bottom regions.The specimens were subjected to push-out strength test in a universal testing machine at crosshead speed of 0.5 mm/min.The experimental data were submitted to one-way ANOVA and LSD test(α=0.05).The results of the failure model of the specimens were observed through microscope and tested for statistical analysis with chi-square Test.Test Two: Sixty freshly extracted first premolar of mandibular with single root canal were divided into 4groups(n=15)with endodontically treated.The fiber posts were cemented with total-etch adhesive system.All of the teeth were divided into four groups according to the following post surface treatments:(group A)no surface treatment;(group B)application of silane coupling agent;(group C)application of silane coupling agent and followed by 35% phosphate acid corrosion agent;(group D)application of silane coupling agent and followed by 5% hydrofluoric acid gel.Each group was divided into 3 subgroups(n=5)for no soaking(A1,B1,C1,D1),soaking in37℃ artificial saliva for 24 hours(A2,B2,C2,D2)and 6 months(A3、B3、C3、D3).Each root was sectioned perpendicularly to its long axis to create 6 specimens of thin slices with 1-mm thickness for a push-out bond strength test.The specimens were divided into upper,middle,and bottom regions.The specimens were subjected to push-out strength test in a universal testing machine at crosshead speed of 0.5mm/min.The experimental data were submitted to one-way ANOVA and LSD test(α=0.05).The results of the failure model of the specimens were observed through microscope and tested for statistical analysis with chi-square Test.Results:1.In test one,the bond strength of fiber posts was decreased with the increase ofthe depth of post file(P <0.05)in groups of the total-etch adhesive system(group A)and self-adhesive system(group C).But the bond strength of fiber posts in groups of the self-etch adhesive system(group B)was not statistically significant(P >0.05).In test two,the bond strength of fiber posts was decreased with the increase of the depth of post file(P <0.05).2.There was no significant difference in the bond strength between the groups of no soaking,soaking in 37℃ artificial saliva for 24 hours and 6 months(P> 0.05).3.In test one,on the upper region of the post files,the bond strength of fiber posts of total-etch adhesive system(group A)were maximum,and the self-etch adhesive system(group B)were minimum(P <0.05);On the middle region of the post files,there was no statistically significant of the bond strength among the three groups;On the bottom region of the post files,the bond strength of total-etch adhesive system(group A)were maximum,and the self-adhesive system(group C)were minimum(P <0.05).In test two,on the three regions of the post files,the maximum bond strength of fiber posts were the group of application of silane coupling agent and followed by 5% hydrofluoric acid gel(group D),the minimum group was the group with no surface treatment(group A),and there were statistically significant when they compared with the other groups(P <0.05).There was no statistically significant between Group B and group C(P> 0.05).4.The analysis of fracture models of fiber posts shows that the bonding interface failure is dominant,and the cohesive failure of the resin materials of the fiber posts are less,the mixed failure was also less.There was no statistically significant among the three kinds of fracture models.Conclusion:under the condition of this experiment:1.The bond strength values were significantly affected by the type of resin cement materials,the depth of post pile and the surface treatment of the fiber posts.2.After the surface treatment with the silane coupling agent,the bond strength of fiber posts increases,and application of silane coupling agent following the 5%hydrofluoric acid gel can increase the bond strength significantly.3.In 6 months,there were no significant affects of the change in time that on the bonding strength of fiber posts.4.The mainly failure of fiber posts in the bond failure,that occurred between the bonding interface of the resin cement and root canal,and the resin cement and fiber post.