title: Congenital and acquired mandibular asymmetry: Mapping growth and remodeling in 3 dimensions.
abstract: Disordered craniofacial development frequently results in definitive facial asymmetries that can significantly impact a person's social and functional well-being. The mandible plays a prominent role in defining facial symmetry and, as an active region of growth, commonly acquires asymmetric features. Additionally, syndromic mandibular asymmetry characterizes craniofacial microsomia (CFM), the second most prevalent congenital craniofacial anomaly (1:3000 to 1:5000 live births) after cleft lip and palate. We hypothesized that asymmetric rates of mandibular growth occur in the context of syndromic and acquired facial asymmetries.
  
  
  
  To test this hypothesis, a spherical harmonic-based shape correspondence algorithm was applied to quantify and characterize asymmetries in mandibular growth and remodeling in 3 groups during adolescence. Longitudinal time points were automatically registered, and regions of the condyle and posterior ramus were selected for growth quantification. The first group (n = 9) had a diagnosis of CFM, limited to Pruzansky-Kaban type I or IIA mandibular deformities. The second group (n = 10) consisted of subjects with asymmetric, nonsyndromic dentofacial asymmetry requiring surgical intervention. A control group (n = 10) of symmetric patients was selected for comparison. A linear mixed model was used for the statistical comparison of growth asymmetry between the groups.
  
  
  
  Initial mandibular shape and symmetry displayed distinct signatures in the 3 groups (P <0.001), with the greatest asymmetries in the condyle and ramus. Similarly, mandibular growth had unique patterns in the groups. The dentofacial asymmetry group was characterized by significant asymmetry in condylar and posterior ramal remodeling with growth (P <0.001). The CFM group was characterized by asymmetric growth of the posterior ramus (P <0.001) but relatively symmetric growth of the condyles (P = 0.47).
  
  
  
  Forms of CFM are characterized by active and variable growth of the dysplastic side, which has a distinct pattern from other disorders of mandibular growth.
authors.affiliation: Lecturer, Section of Orthodontics, University of California, Los Angeles, Calif. Electronic address: rchristian@g.ucla.edu.
authors.forename: R Christian
authors.initials: RC
authors.lastname: Solem
authors.affiliation: Associate professor, Federal University of Rio de Janerio, Rio de Janerio, Brazil; postdoctoral fellow, School of Dentistry, University of Michigan, Ann Arbor, Mich.
authors.forename: Antonio
authors.initials: A
authors.lastname: Ruellas
authors.affiliation: Statistical consultant, Institute for Digital Research and Education, University of California, Los Angeles, Calif.
authors.forename: Joni L
authors.initials: JL
authors.lastname: Ricks-Oddie
authors.affiliation: Adjunct clinical assistant professor, Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Michigan, Ann Arbor, Mich.
authors.forename: Katherine
authors.initials: K
authors.lastname: Kelly
authors.forename: Snehlata
authors.initials: S
authors.lastname: Oberoi
authors.forename: Janice
authors.initials: J
authors.lastname: Lee
authors.affiliation: Professor, School of Dentistry, University of California, San Francisco, Calif.
authors.forename: Arthur
authors.initials: A
authors.lastname: Miller
authors.affiliation: Assistant professor, Department of Orthodontics and Pediatric Dentistry, School of Dentistry, University of Michigan, Ann Arbor, Mich.
authors.forename: Lucia
authors.initials: L
authors.lastname: Cevidanes
mesh_terms: D000293:Adolescent; D000465:Algorithms; D016723:Bone Remodeling / Q000502:physiology; D016022:Case-Control Studies; D054893:Cone-Beam Computed Tomography; D005146:Facial Asymmetry / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006053:Goldenhar Syndrome / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008334:Mandible / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000254:growth & development; D012189:Retrospective Studies