Methods of strengthening the bonding interface between fiber posts and resin cements
Dakhil, Siraj A.
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When the remaining crown structure is weak and insufficient to hold the core materials, a post cemented into a root canal may be the method of choice to withhold a core build up. Debonding is one of the most common complications associated with fiber posts cemented inside a root canal. Objective: Find the proper surface treatments of fiber posts that will enhance bonding to resin cements. Methods: In this study we utilized one stainless steel post PP (ParaPost XP, Coltene/Whaledent); one modified glass ionomer cement FJ (Fuji I CEM, GC America); two fiber post systems: RX (Rely X Fiber Post, 3M ESPE) and UC (UniCore Post, Ultradent); and two resin cement systems: RU (RelyX Unicem 2 Clicker, 3M ESPE) and PC (ParaCore, Coltene/Whaledent). In the first part of the study, sixty samples of untreated dowels (control) were divided into 6 groups according to the bonded post/cement systems (n=10): (PP/FJ), (PP/PC), (RX/RU), (RX/PC), (UC/PC), and (UC/RU). In the second part of the experiment, 240 fiber posts were divided according to the bonded post/cement systems (n=60): (RX/RU), (RX/PC), (UC/PC), and (UC/RU). Before cementation, the fiber posts in each group received one of 6 treatments (n=10): silane, hydrogen peroxide/silane, hydrofluoric acid/silane, dimethyl sulfoxide/silane, sandblasting/silane, tribochemical coating/silane. Silane application was for 60s. Sandblasting and tribochemical coating invoIved blasting rotating posts with 25[mu]m AlO and 30[mu]m silica-modified AlO (CoJet, 3M ESPE), respectively, from a nozzle positioned at 1-mm distance and moving at a rate of 0.18 mm/s. In one group, posts were immersed in 35% liquid HO for 5 minutes. When dimethyl sulfoxide (DMSO) was used, the posts were submerged in DMSO for 5 minutes. For hydrofluoric acid treatment, a 9% hydrofluoric acid (HFA) gel was applied on the post surface for 60s. Specimens were prepared for pull testing by cementing the parallel coronal side of the post 3-mm deep into a coupling nut to form the test side. The tapered apical side was cemented 9-mm into the coupling nut to form a grip. After 24h, the pull-out test was done in a universal testing machine at a crosshead speed of 1.0mm/min. The maximum force at debonding was recorded and bond strength was calculated in MPa. [TRUNCATED]
Thesis (DSD) --Boston University, Goldman School of Dental Medicine, 2015 (Department of Endodontics).Includes bibliographic references: leaves 82-88.
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