Abstract: ObjectiveTo observe the effects of the two kinds of rigid fixed bridge design on the stress of the alveolar bone of mandibular first molar after hemisection.MethodsThe normal mandibular first molars were selected as control group. The two-abutment teeth and three-abutment teeth rigidly fixed bridge designs were selected as trial group. Stress distributions in the remaining sections of the alveolar bone models were evaluated with photoelastic stress analysis method.ResultsThe stress values of two kinds of rigid fixed bridge design were higher than the control group but still below the twice. There was no significantly difference between two-abutment teeth rigidly fixed bridge design and three-abutment teeth rigidly fixed bridge design (P>0.05).ConclusionTwo-abutment teeth rigidly fixed bridge of mandibular first molar should be chosen after hemisection.

Key words: hemisection, rigid fixed bridge, photoelastic experiment, stress analysis