Effects Of Surface Treatments On Bond Strength Of Fiberposts And The Fracture Resistance Of Teeth

ObjectiveThe purpose of this in-vitro study is to assess the effects of different surface treatments on bond strength of fiber posts to a resin cement through "thin-slice" push out test,compare the bond strength for different regions of the root and evaluate the effects of surface treatments on the fracture resistance of root,so that appropriate surface treatment methods can be used for clinical selection and providing a theoretical basis for improvement bond strength of fiber posts to a resin cement/core materials.Method(1)Effects of surface treatments on bond strength of fiber posts. The fiber posts were divided into six groups according to different surface treatment techniques, including silanization,sandblasting,etching with hydrogen peroxide, sandblasting and silanization, etching with hydrogen peroxide and silanization and no treatment performed.No treatment performed served as the control group. All fiber posts were luted with a composite resin luting agent in the canal roots.After cementation,the roots were subjected to simulated aging conditions consisting of mechanical loading cycles and thermal cycles. The roots were sectioned into slices with 1 mm thickness and a push-out test was performed on three different sections of each root to measure bond strengths. Test piece following testing was placed under optical microscope to observe the breakage method.(2) Effects of surface treatment on the fracture resistance of teeth restored with fiber posts and core system. The fiber posts were divided into three groups according to different surface treatment techniques, including sandblasting,etching with hydrogen peroxide,and no treatment performed.No treatment performed served as the control group. All fiber posts were luted with a composite resin luting agent in the canal roots.The teeth were restored with composite resin cores and metal crowns. After cementation,the teeth were subjected to simulated aging conditions consisting of mechanical loading cycles and thermal cycles. All teeth were loaded in a mechanical testing machine with a compressive load(N) applied at 30 degree to the long axis of the specimen at acrosshead speed of lmm/min until fracture. The fracture load and fracture mode of each teeth were recorded.Results1. No significant difference in bond strength was determined between the silaned and no- treatment groups (P> 0.05).2. Bond strength was significantly greater in the groups performed with surface treatments except the silaned compared with the control group (P< 0.05). 3. Bond strength was significantly greater in the sandblasting and silanization group and etching with hydrogen peroxide and silanization group compared with sandblasting group and etching with hydrogen peroxide group(P< 0.05).4.The coronal third of the root resulted in statistically greater bond strengths than the medium third,whose bond strength was significantly greater than the apical third(P< 0.05).5.The fracture resistance of sandblasting and hydrogen peroxide groups were higher than the the control group.Conclusion1. The use of a silane coupling agent only did not increase the bond strength between fiber posts and a resin cement, sandblasting and etching with hydrogen peroxide can increase the push-out bond strengths of fiber posts and improve the fracture resistance of teeth.2.Bonding was more predictable at the coronal level of the root.