Objective To compare the difference of stress distribution among models with different fiber frameworks. Methods Four models were generated in Marc 2003 software. Four types of loads simulating normal mastication were selected. The stress within models was calculated, and output by means of graph and data. Results There was stress concentration around connectors and retainers near connectors under cusp- fossa load, occlusal even load, and lateral load. When dentures were reinforced with fiber framework, area of stress concentration and principal stress max could decrease in comparison with pure composite resin bonded fixed partial denture. Under buccal- lingual load, there was another stress concentration around central fossa beside above two stress concentration areas. Only modified fiber framework constructed with both mesial- distal and lingual- buccal directional glass fiber could markedly reduce principal stress under buccal- lingual cusp loads. Conclusion Under 4 types of loads simulating normal mastication, three critical regions were disclosed at the area of retainers adjacent connectors, connectors and occlusal central fossa and fissures. Only modified fiber framework constructed with both mesial- distal and lingual - buccal directional glass fiber could markedly reduce stress concentration under buccal- lingual cusp loads.
