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

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.