Bond strength and quality of the bond interface of multifilament glass fiber postsluted onto long oval root canals after post space cleaning with ultrasonic insert andmagnification with clinical microscope
The aim of the present will be to evaluate the bond strength (BS) and the adhesive interface of multifilament glass fiber postsluted ontolong oval root canals after cleaning the post space with the aid of ultrasonic insert and magnification with clinical microscope. Mandibular molars will be scanned with cone beam computed tomography for the selection of 44 distal roots with long oval root canals, considering the ratio of larger/smaller diameter between 2.5 and 4.0 and circularity <0.35. Biomechanical preparation will be performed with a Reciproc R50 file and the filling will be performed using the lateral condensation technique with AH Plus sealer. The sample will be distributed in 4 groups according to the restorative protocol used: GI - preparation of the post space with drill and cementation of conventional glass fiber post (WhitePost DC #0,5, FGM, Joinvile, SC, Brazil); GII -filling removal with heated condenser and cementation of Comet Tail® #4 multifilament posts according to the manufacturer's instructions (Synca, Repentigny, Quebec, Canada); GIII - filling removal with heated condenser, complementary cleaning protocol with ultrasonic insert, and cementation Comet Tail® #4 multifilament posts; and GIV - filling removal with heated condenser, complementary cleaning protocol with ultrasonic insert with the aid of magnification usingclinical microscope, and cementation of Comet Tail® #4 multifilament posts. The posts will be treated with 10% hydrofluoric acid and cemented with RelyX U200 cement. The roots will be transversely sectioned into 1 mm thick slices (2 slices of each root third). The most cervical slices of each third will be used to evaluate the BS through the push-out test with a speed of 0.5 mm/min followed by the analysis of the failure pattern in a stereomicroscope. The most apical slices of each third will be selected for the analysis of the post/cement/dentin interface in scanning electron microscopy with magnifications of 100, 1000, 2000 and 4000X. The BS and interface adaptation data will be subjected to statistical analysis.
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