| Objectives:The purpose of this study was to assess the effects of aging on bond strength of glass fiber posts using three kinds of different resin adhesive in different root regions,providing reference for clinical work to choose the appropriate luting cements. Materials and Methods:Mandibular premolar teeth were decoronated with a diamond disk above the cement and enamel junction 2mm and treated endodontically. Following the post space preparation, they were used for two different experiments.Thirty mandibular premolar teeth were used in the first experiment, and were grouped into three groups of 10 specimens each. Fiber-reinforced composite posts were cemented with three resin cement systems:(a)total-etching adhesive system,(b)self-etching adhesive system,(c)self-adhesive system. Each group was selected 10 samples randomly, and divided into two subgroups(n = 5), thermal cycle processing(A1?B1?C1)and untreated(A2?B2?C2)respectively. Each root was sectioned into six sections with a thickness of 1 mm. The push-out test was performed with a universal testing machine at a cross-head speed of 0.5 mm/min, and bond strength values obtained were statistically analyzed by analysis of variance(muti-factor MANANOVA) and multiple comparison test of Tukey, with level of significance of 5%.The fracture mode was Observed through microscope.Thirty mandibular premolar teeth were used in the second experiment, and were grouped into three groups of 10 specimens each. Fiber-reinforced composite posts were cemented with three resin cement systems:(a)total-etching adhesive system,(b)self-etching adhesive system,(c)self-adhesive system. Each group was divided into two subgroups(n = 5), dynamic loading processing(A1?B1?C1)and untreated(A2?B2?C2)respectively. Each root was sectioned into six sections with a thickness of 1 mm. The push-out test was performed with a universal testing machine at a cross-head speed of 0.5 mm/min, and bond strength values obtained were statistically analyzed by analysis of variance(muti-factor MANANOVA) and multiple comparison test of Tukey, with level of significance of 5%.The fracture mode was Observed through microscope. Results: 1,With the increase of post space,bond strength of three-step adhesive total-etch system and self-adhesive system decreased significantly(P<0.05),no statistically significant differences in bond strength of the self-etch system in different root regions(P>0.05). 2,On the coronal 1/3 regions of the roots,The mean push-out bond strength was highest for self-adhesive system, followed by total-etch system, The lowest mean push-out bond strength was seen with self-etch system(P<0.05);On the middle 1/3 regions of the roots, self-adhesive system had higher bond strength than total-etch system and self-etch system,total-etch system had the lowest bond strength(P<0.05);On the apical 1/3 regions of the roots, self-etch system resulted in higher push-out values than self-adhesive system and total-etch system(p < 0.05). 3,Thermal cycle may decrease the bond strength of total-etch system and self-etch system(P<0.05),but there was no statistical difference on self-adhesive system(P > 0.05).Cyclic loading may decrease the bond strength of the three different resin cement(P<0.05). 4,The three different resin cement showed mainly adhesive failure between the resin cement and root canal, No statistical difference was showed between the failure modes of all groups(P > 0.05). Conclusion: 1,The bond strength values were significantly affected by aging, resin adhesive and root canal region. 2,The adhesive failure were occured between the resin cement and root canal. |
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