Facial Asymmetry Phenotypes in Adult Patients With Bilateral Cleft Lip and Palate and Skeletal Class III Malocclusion Using Principal Component Analysis and Cluster Analysis.

Abstract

Objective: To classify and characterise facial asymmetry (FA) phenotypes in adult patients with bilateral cleft lip and palate (BCLP) and skeletal Class III (C-III) malocclusion.

Materials and methods: The samples consisted of 72 adult BCLP patients (56 males, 16 females; mean age, 21.0 years), who were candidates for orthognathic surgery (OGS) or had undergone OGS for the correction of C-III malocclusion. Because BCLP patients have two cleft sides, the vertically longer defect (VLD) side was used for the reference side. Twenty-three cephalometric parameters were measured in posteroanterior cephalograms taken at least 1month before OGS. Principal component analysis was performed to obtain seven representative parameters [ANS-deviation (mm), U1-deviation (mm), L1-deviation (mm), Me-deviation (mm), MaxAntOP-cant (°), MaxPostOP-cant (°), ManBorder-cant (°)]. K-means cluster analysis was conducted using these representative parameters. Differences in cephalometric parameters among the clusters were statistically analysed.

Results: FA phenotypes were classified based on the deviation direction towards the VLD or less VLD side and the upward or downward cant in the VLD side. The classifications were: (1) Symmetry type (20.8%); (2) MxMn-VLD-dev & MxMn-no-cant type (22.2%); (3) MxMn-less-VLD-dev & Mnbase-VLD-down-cant type (9.7%); (4) Mn-less-VLD-dev & MxMn-VLD-down-cant type (20.8%); (5) MxMn-no-dev & MxMn-VLD-up-cant type (19.4%), and (6) MxMn-VLD-dev & MxMn-VLD-up-cant type (6.9%). The possible etiologies of FA phenotypes included ANS deviation, movement of the maxillary incisor by pre-operative orthodontic treatment, and adaptive growth or compensatory growth of the maxilla and/or mandible.

Conclusion: This FA phenotype classification could serve as a guideline for diagnosis and OGS planning for BCLP patients.