Abstract: Objective：To observe the effects of a modified semi-fixed bridge to restore a missing posterior tooth for three years. Methods: In the study, 38 cases with a posterior tooth missed were chosen as experiment group. The inclusion criteria for these cases required that one abutment tooth be defected, and another abutment  intact. The missed posterior tooth was restored with a modified semi-fixed bridge in which a metal wing retainer was applied to the intact abutment tooth and a full crown retainer was applied to the defected abutment tooth, and the non-rigid connector linked to the metal wing retainer and the pontic, while the rigid connector linked to the full crown retainer and the pontic. And 42 cases with same abutment conditions were chosen as control group. These control patients were treated with classical rigidly-fixed partial dentures. The clinical effects regarding the bridge survival, abutment conditions, and etc. were observed by examination. Results: The average observation time for experiment group was 40.3 months (from 9 to 60 months). One case failed with loose crown retainer after 7 months’ usage.  Another failed case was the same performance after 20 months’ wearing. The restorations were rebounded after the inner face of crowns was treated, and they were used normally. No loose abutment and retainer, no decayed abutment teeth were found, and the marginal adaptations between retainers and abutment teeth were good. The average observation time of control group was 44.7 months（from 22 to 50 months）. No secondary decays and loose abutment teeth were detected and the marginal adaptation of the retainers was good.  Conclusion: This modified semifixed bridge has similar survival rate and clinical effects to restore a missing posterior tooth when compared with the traditional rigidlyfixed partial dentures. But the longterm observation is required.

Key words: Tooth loss, Denture, partial, fixed, resin-bonded, Attachment, dental slotted