Three-dimensional assessment of craniofacial asymmetry in children with transverse maxillary deficiency after rapid maxillary expansion: A prospective study

Abstract

Objective: The aim of this study was to evaluate craniofacial asymmetry in children with transverse maxillary deficiency, with or without functional unilateral posterior crossbite (UPC), before and after rapid maxillary expansion (RME).

Setting and sample population: A sample of 51 children with cone beam computed tomography scans obtained before RME (T1) and a year after RME (T2).

Material and methods: This prospective study consisted of 2 groups: 25 children with functional UPC (6.77 ± 1.5 years) and 26 children without UPC (7.41 ± 1.31 years). Linear and angular measurements were obtained from zygomatic, maxilla, glenoid fossa and mandible, using original and mirrored 3D overlapped models. All right and left side comparisons in both groups and intergroups asymmetries were compared using MANOVA and t test for independent samples, respectively, statistically significant at P < .05.

Results: The UPC group showed no side differences, but mandibular horizontal rotation at T1, and this asymmetry was improved in T2. The non-UPC group showed at baseline significant lateral asymmetry in orbitale, position of palatine foramen, respectively, in average 2.95 mm and 1.16 mm, and 0.49 mm of average asymmetry in condylar height. The glenoid fossa was symmetric in both groups at T1 and T2.

Conclusions: Children with transverse maxillary deficiency showed slight morphological asymmetry, located in the mandible position in cases of UPC, and in the orbital and maxillary regions in cases without UPC. One year after RME, patients improved their craniofacial asymmetry, with significant changes in the mandible and correction of the mandibular rotation in patients who presented UPC.

Keywords: cone beam computed tomography; craniofacial abnormalities; crossbite; facial asymmetry; maxillary expansion.

FIGURE 1

Anatomical landmarks used in measurement’s method. A, Landmarks of measurement’s method: orbitale (Or): most inferior point at the inferior contour of the orbit; zygomaticomaxillary (ZM): most inferior point at the zygomatic maxillary suture; anterior nasal spine (ANS): most anterior point at the anterior nasal spine; palatine foramen (PalF): the middle and inferior point at the palatine foramen; GlF (glenoid fossa): most superior point at the glenoid fossa; sella (S): midpoint at the sella turcica; basio (Ba): most inferior point at the anterior border of magnun foramen; 2-D: mandibular landmarks: condilium (Co): most superior point on the curvature of the condylar head; anterior pole (CoA): most anterior point of the condylar head; posterior pole (CoP): most posterior point of the condylar head; medial pole (CoM): most medial point of the condylar head; lateral pole (CoL): most lateral point of the condylar head; centre of condyle (CtCo): centre point on the line connecting the centres of latero-medial and antero-posterior distances, sigmoid posterior (Sig`): most posterior point of the projection of sigmoid notch point using a line parallel to Frankfurt plane; gonion (Go): midpoint of the angle of the mandible determined by bisecting the angle formed by the mandibular plane and the adjacent line to mandibular ramus; gnathion (Gn): most anteroinferior and midline point on the contour of the bony chin symphysis, determined by bisecting the angle formed by the mandibular plane and a line through pogonion and nasion; and menton (Me): most inferior midline point on the mandibular symphysis

FIGURE 2

Craniofacial roll and yaw assessment in the study’s method. A, Illustration of roll and yaw measurement of Orbitale. B, Illustration of yaw in mandible, using superimposition of original and mirrored models

FIGURE 3

Summary illustration of the RME treatment results in asymmetry. A, 3D models in T1 and T2 of patient with functional unilateral posterior crossbite showing the shift change towards the left side after RME. B, 3D superimposition of patient with transverse maxillary deficiency and no posterior crossbite in T1 and T2 showing craniofacial regions more prominent at right side, as seen in zygomatic arch and maxilla