Unilateral Functional Crossbite Causes Facial Asymmetry of the Mandible

Orthodontics - September 30, 2013 - Vol. 27 - No. 9

Unilateral functional crossbite causes facial asymmetry of the mandible, which becomes worse with time.

Article Reviewed: Three-Dimensional Evaluation of Facial Asymmetry in Association With Unilateral Functional Crossbite in the Primary, Early, and Late Mixed Dentition Phases. Primozic J, Perinetti G, et al: Angle Orthod; 2013;83 (March): 253-258.

Background: When a child presents with a unilateral posterior crossbite and functional shift of the mandible, an orthodontist must decide whether to treat that problem early, thus producing 2 phases of orthodontic treatment, or to simply wait and treat the crossbite when all permanent teeth have erupted. Is there any advantage to preventing further asymmetry of the face by treating the child earlier?

Objective: To consider the degree of facial asymmetry using 3-dimensional laser scanning methodology in growing subjects according to their dentition phase when a unilateral functional crossbite is present.

Design: Observational study.

Methods: The authors assembled a sample of 234 Caucasian children between ages 4 and 12 years. One-third of the sample had posterior unilateral functional crossbites with a shift of the mandible. The other two-thirds of the sample had no malocclusion. They were divided into dentition stages of primary, early mixed, and late mixed dentition. The authors used 3-dimensional laser scanning technology to produce a color map of the face of each child to determine the position and amount of facial asymmetry. They then quantitatively compared the degree of facial asymmetry at these different stages of dental development.

Results: Facial asymmetry of the mandible was prominent and prevalent at all dentition stages. Interestingly, asymmetry of the middle portion of the face, the maxilla, was apparent and more prominent after the primary dentition and in the early mixed dentition.

Conclusions: Facial asymmetry of the mandible is consistently present in patients who have a functional crossbite; however, asymmetry of the maxilla begins to occur in the early mixed dentition.

Reviewer's Comments: My conclusions from this study are that if one wants to avoid compensatory changes in the maxilla from a functional crossbite, then one should resolve the crossbite and eliminate the functional shift before the patient gets to be late mixed dentition. This would suggest that children with posterior functional crossbites should receive an early phase of treatment to correct the crossbite and avoid alterations in the maxilla that can occur with time.(Reviewer–Vincent G. Kokich, Sr, DDS, MSD).

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