Comparison Of The Shear Bond Strength After Filling Wedge-shaped Defect With Different Materials In Vitro

Objective: To observe and compare the shear bond strength after filling wedge-shaped defect with different materials(GIC, FujiⅡ, FujiⅡLC Improved, flowable composites, Filtek^TM Z350Nano-resin, Sandwich technique of flowable composites+ Filtek^TM Z350), and contrast with the shear bond strength of GIC and Sandwich technique of GIC+ Filtek^TM Z350 Nano-resin. This paper aims at choosing the best materials for clinical use in filling wedge-shaped defect.Methods: seventy intact, subfissure-free, caries-free, extracted human premolars were collected, cleaned and were preserved in distilled water of -20℃within three months.The Class V cavities were prepared on the buccal surface and were extended below the cement-enamel junction(CEJ). The cavities were grinded with a carbide bur in a high-speed handpiece equipped with water spray: each had a occluso-gingival height of 3.5mm, a depth of 1.5mm, from mesio surface to distal surface. (an internal line angle of 90°). The periodontal probe was used to gauge the consistency of cavity size each time. The surface was cleaned with EDTA(0.5mol/L, PH=7.4)for 1 minite before filling.Seventy speciments were randomly divided into five experiment groups and two control groups. The speciments were filled with different materials as following:Group1: Traditional glass ionomer cement(GIC)(control group);Group2: Sandwich technique of GIC+ Filtek^TM Z350 Nano-resin(control group);Group3: Glass ionomer cement FujiⅡ( GIC FujiⅡ); Group4: Light-cured, resin-reinforced glass ionomer cement (GIC FujiⅡLC Improved);Group5: Flowable composite(Esthst-X Flow);Group6: Filtek^TM Z350 Nano-resin;Group7: Sandwich technique of Esthet-X Flow+Filtek^TM Z350Nano-resinGroup3 to Group7 were used as experimental groupsWhen all the speciments had been filled, seventy speciments were putted into normal saline at ordinary temperature for 24 hours. Then the teeth were putted into 5℃(±2℃)and55℃(±2℃)water 1 minute alternately in each bath. A total of 800 cycles were used for all speciments. Then the roots of the teeth were fixed in self-curing resin pedestal, which was 1.0cm×1.0cm×2.0cm, with exposing the cervical of filling areas. The tooth long axis was vertical with the groud. After the temperature cycling, the speciments were fixed to the fatigue cycle testing machine for the load cycling, with the 10Hz rate, (100±10)N power, 1.5mm-2mm amplitude, total 50000 times.After the load cycling, all speciments were divided into two parts along the long axis of teeth with a silicon carborundum disc in a low-speed handpiece equipped with water spray. The part which retains self-curing resin pedestal was fixed to the universal testing machine, the shear speed was 0.5mm/min, and the maximum shear stress values were recorded by the computer.Kruskal-Wallis H test was used to analyze different shear stress values among seven groups; Wilcoxon test was used for multiple-comparison. Asα=0.05, if P value is<0.05, there is a difference statistically. The characters of seven materials in this study were evaluated by the results of the shear bond strength data.Results:According to the test of the shear bond strength, the data of the shear bond strength were: GIC10.61±2.66N, Sandwich technique of GIC+ Filtek^TM Z350 40.48±2.74N, FujiⅡ21.60±3.67N, FujiⅡLC Improved 29.33±2.61N, flowable composites 42.82±2.09N, Filtek^TM Z350Nano-resin 41.32±5.22N, Sandwich technique of flowable composites+ Filtek^TM Z350 55.78±2.89N. the result of the Kruskal-Wallis test showed there was a significant difference among the seven groups(H=63.059, P <0.05) .The results of Wilcoxon test indicated that there was no difference statistically in the shear bond strength between group 2, group 5 and group 6(P>0.05). The shear bond strength of group1, group 3, group 4and group7 were different from other groups(P<0.05).Conclusion:1 The shear bond strength of glass ionomer cements such as GIC, FujiⅡ, FujiⅡLC were lower than other groups. The shear bond strength of group FujiⅡLC was higher than the group of FujiⅡand GIC, The shear bond strength of group GIC was the lowest.2 The shear bond strength of group Esthet-X Flow and Filtek^TM Z350 were higher than theGIC+ Filtek^TM Z350, and the shear bond strength of group Esthet-X Flow was little higher than the group Filtek^TM Z350.3 The shear bond strength of the group of Sandwich technique of Esthet-X Flow + Filtek^TM Z350 Nano-resin was the highest among all the groups.