ALL-CERAMIC RESIN-BONDED BRIDGES - A 3-DIMENSIONAL FINITE-ELEMENT ANALYSIS STUDY

Resin-bonded fixed partial dentures (FPD) with a metal framework have some disadvantages: a grey shimmer of the metal wings through the abut ment teeth, a higher corrosion rate, and an allergenic potential of th e non-precious alloys used. The Al2O3 ceramic In-Ceram(C) seems to be strong enough to serve as a framework for resin-bonded all-ceramic FPD s. Because of the fact that ceramic wings often don't have enough inte r-occlusal space, a new preparation design was developed, The objectiv e of this study was to determine the influence of load orientation (45 degrees and 60 degrees) and the design of the interproximal connector on the stress distribution in the bridges. A 3-dimensional finite-ele ment model was developed to simulate the anatomical situation. The bit ing force was assumed as 250 N and oriented in oro-buccal direction, T he loading-point was palatal 1.5 mm beneath the incisal edge. It was f ound that stress generally increased with an angle of the biting force of 60 degrees. A small interdental connector (3 mm height) and/or str ong interdental separation resulted in stresses of up to 455 MPa (45 d egrees) or 534 MPa (60 degrees). Less separation with rounded edges an d a higher connector (4 mm) reduced the stress to 122 MPa (45 degrees) and 143 MPa (60 degrees). Due to an average tensile strength of In-Ce ram at 340-400 MPa, an all-ceramic resin-bonded FPD may only be recomm ended if the height of the connector could be minimum 4 mm, Rounded ed ges and little interdental separation are significant for stress reduc tion.