Abstract: PURPOSE: To investigate the symmetry of nasal maxillary complex in the three-dimensional directions of patients with unilateral complete cleft lip and palate(UCLP) at the stage of mixed dentition. Methods: Craniofacial cone-beam CT(CBCT) images of 20 UCLP patients at the stage of mixed dentition were selected. Three-dimensional reconstruction of bone tissue was carried out by Mimics software, nasal root point and 32 markers with the same name of the healthy side and the cleft side of the nasal maxillary complex were traced, three-dimensional reference planes were set up, then the distances between the points to the three-dimensional planes were measured respectively. SPSS 22.0 software package was used to analyze the data. Results: In the horizontal direction, compared with the non-cleft side, the width of the cleft side of the maxilla at INM and SPC was smaller, the width of maxilla at LPA and SPr was larger, the differences were statistically significant (P<0.05). In the sagittal direction, compared with the non-cleft side, the depth of LPA, Maz and SPr at the cleft side was larger, the depth of SPM and SPC was smaller, the differences were statistically significant (P<0.05).In the vertical direction, the positions of LPA, INM and Maz at the cleft side was lower than the non-cleft side, SPC and SPr were higher, the differences were statistically significant(P<0.05). The remaining points had no significant difference (P>0.05). Conclusions: The nasal maxillary complex of UCLP patients at the stage of mixed dentition is asymmetric in three directions. The asymmetric locations were mainly located in the nasal cavity and alveolar bone. No obvious asymmetry is found in the orbital region and the maxillary region far from the cleft.

Key words: Cleft lip and palate, Nasal maxillary complex, Symmetry, Cone-beam CT