Abstract: PURPOSE: In this study, the symmetry of neomandible and whether meeting the standard of dental implant after reconstruction with iliac bone flap were measured to make sure the advantages and disadvantages of different iliac crest orientations. METHODS: Patients who underwent mandibular defect reconstruction with iliac bone flap at Peking University School and Hospital of Stomatology from January 2017 to December 2019 were included in this study, and divided into iliac crest oriented to alveolar process group (group A) and iliac crest oriented to lower mandibular margin group (group B). The patients' basic information and CT image data after operation were collected. Simplant and Proplan software were used to measure the symmetry, the length of bone segment, the height, the width of alveolar process side and the distance between jaws and iliac crest after reconstruction(opposite to upper incisor,canine and first molar). The data was analyzed using SPSS 25.0 software package. RESULTS: There were 15 patients in group A and B respectively, the average age was 37.7 years old. The asymmetry rate of LC defect type at the lower edge of the mental foramen in group A was less than that in group B. There was no significant difference in bone length between group A (49.43±4.17)mm and group B (52.25±3.79)mm. The widths of occlusal side in group A (opposite to upper incisor, canine and first molar) were (11.40±0.63), (12.15±0.46), (13.15±0.62)mm, and (7.93±0.55), (8.97±0.34), (8.70±0.49)mm(P<0.05) in group B, respectively. The bone height opposite to upper first molar was(29.80±1.17)mm in group A, which was significantly higher than (25.42±1.17)mm in group B(P<0.05). The intermaxillary distance of group A was less than that of group B, the distance of first molar was (10.89±1.07)mm in group A and (14.33±0.76)mm in group B(P<0.05). CONCLUSIONS: When mandibular dentulous defect is reconstructed with vascularized iliac bone flap, the iliac crest oriented to the alveolar process side can get better symmetry, wider alveolar ridge and more suitable intermaxillary distance than iliac crest oriented to the lower margin of the mandible.

Key words: Iliac crest, Mandibular defect, Symmetry, Reconstruction, Intermaxillary distance