CBCT-based assessment of maxillomandibular asymmetry at different growth stages in unilateral cleft lip and palate

Objective: This study aimed to assess three dimensional maxillomandibular skeletal asymmetry in patients with unilateral complete cleft lip and palate (UCLP) during different developmental periods using cone-beam computed tomography (CBCT), and to investigate the underlying causes of mandibular deviation. Methods: The experimental group comprised 60 patients with nonsyndromic unilateral cleft lip and palate (UCLP), while the control group included 60 skeletal class I patients without any craniofacial cleft deformities. Based on Cervical vertebral maturation (CVM), the participants were divided into three growth stages: pre peak, peak, and post peak of puberty growth, with 20 individuals per group. Cone-beam computed tomography (CBCT) scans of maxillofacial region were analyzed using Mimics 21.0 software. Pearson correlation analysis was performed to identify factors associated with mandibular deviation. Results: In the UCLP group, maxillary asymmetry was significantly greater than in the control group across multiple landmarks, particularly at the paranasal point, maxillary first molar, zygomaticofrontal suture, infraorbital foramen, zygomatic arch, and zygomaticomaxillary suture (all P < 0.05). The differences varied by growth stage: the pre-puberty stage showed notable asymmetries mainly in the paranasal and molar regions; the pubertal stage exhibited the most widespread discrepancies; and the post-puberty stage retained significant asymmetries primarily in the coronal and horizontal dimensions of the midface. Significant overall distributional differences among the three stages were observed for distances from the paranasal point to the horizontal and sagittal planes, and from the zygomaticomaxillary suture to the horizontal plane (all P < 0.05). Correlation analyses revealed that mandibular deviation was significantly associated with maxillary asymmetry indicators, including the vertical offset of the zygomaticomaxillary suture, horizontal offset of the infraorbital foramen, and vertical offset of the zygomatic arch root (all P < 0.05), but not with intrinsic mandibular length discrepancies. Conclusions: Maxillary asymmetry in UCLP becomes more pronounced from the pubertal growth spurt onward, and mandibular positional deviation in UCLP may be associated with maxillary asymmetry rather than with intrinsic mandibular length discrepancies.