OBJECTIVETo analyze stress distribution of two framework designs in compound galvano-ceramic bridges made with three-dimensional finite element models.

METHODSThree-dimensional finite element models were developed for compound galvano-ceramic bridges with two designed retainers of Ni-Cr frameworks which ringed or partially covered the electroformed gold caps. The models were vertically loaded 200 N on the center of the occlusal surface of the pontic and loaded 400 N on the center of buccoclusal marginal ridge from buccal aspect to lingual aspect at a 30 degree angle with the occlusion plane respectively. The stress distributions and the level of stress concentration in the two models were analyzed by the FEA software.

RESULTSStress distributing in two designed framework of compound galvano-ceramic bridges were similar. The highest von Mises stress of compound galvano-ceramic bridges was concentrated in the distal connector of the pontic and retainer. Under the vertical loading, the von Mises stress was 24.17 MPa for the partial cover retainer of the Ni-Cr framework and 24.85 MPa for the circular retainer. Under the lateral loading, the corresponding figures were 42.83 MPa and 42.69 MPa. No matter vertical or lateral loading, the margin of electroformed cap was the concentration area of the von Miese stress.

CONCLUSIONSIn this study, the stress concentration area of compound galvano-ceramic bridges with Ni-Cr framework and electroformed gold caps was the connector and the margin of electroformed cap was the insubstantial area.