Effect of two connector designs on the fracture resistance of all-ceramic core materials for fixed dental prostheses
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This study evaluated how two connector designs impact the fracture resistance of three all-ceramic core material for FDPs: heat pressed lithium disilicate, milled lithium disilicate and milled Y-TZP. Samples bars with 30x4x4 mm3 were fabricated with two connector designs: 0.60 mm (round) and 0.06 mm radius of curvature (sharp). Specimens were subjected to a 3 point bending test. Within the limitation of this study, the following conclusions are drawn: all-ceramic FDPs fractured initially at the gingival surface of one connector and propagated toward the pontic. Y-TZP exhibited higher fracture resistance than lithium disilicate ceramic. Connector design affects fracture resistance of machined ceramics but not pressed ceramic. Lithium disilicate glass ceramic as manufactured for CAD/CAM fabrication showed higher fracture resistance than test samples made with the heat pressing technique in the round connector design. Fracture resistance of milled Y-TZP are less affected by connector design than milled lithium disilicate glass ceramic.