Abstract: Objective　To investigate the effect of different gingival types of fixed bridge on the stress distribution of the abutment and periodontium via the method of three-dimensional finite element analysis. Methods　A fixed bridge with the mandibular second premolar and the second molar acting as the abutment to restore the missing first molar was established using three-dimensional modeling software based on original cone beam computed tomography(CBCT) data of healthy adult dentition. Three different types of bridge gingival ends were simulated, namely modified saddle type, modified crest type and bottom type. After vertical loadings were exerted on three kinds of finite element models respectively, the stress distributions of dentin and periodontal membrane of the fixed bridge abutment were analyzed using ANSYS 17.0 software. Results　①The second premolar teeth always suffered higher stress compared with the first molar teeth under the same loading condition. ②The stress distribution of a single teeth showed no significant difference among three different gingival types of fixed bridge, while the bottom type of prosthesis showed smaller stress in the second premolar teeth and bigger stress in the first molar teeth. ③The stress distribution of the periodontal membrane of the three groups of bridge abutment teeth was as follows: modified saddle type<modified crest type<bottom type. However, the stress in the three groups did not exceed the periodontal reserve of the abutment, and the periodontal reserve of the abutment increased with the decrease of the bridge gingival end volume. Conclusion　①Molars are ideal abutment. The periodontal supporting force of the first molar teeth should be first considered in the restoration. ②The bottom gingival type is more favorable to protect the single root teeth and improves the stress distribution of the fixed bridge. ③All the three kinds of gingival types can afford the daily bite force and have no effect on the health of the periodontal membrane.

Key words: fixed prosthesis, gingival types of fixed bridge, finite element analysis, periodontal potential, Stress