Unconventional usage of the Invisalign Fist system in treating a complete crossbite due to a lateral functional mandibular shift - a case report

Diagnosing a crossbite in a child requires early intervention. A lateral functional mandibular shift is a result of a disproportion in the widths of dental arches. A correct mandibular width usually accompanies the maxillary narrowing. The mandible shifts laterally during the last stage of adduction to one side, experiencing the first occlusal contact usually in the area of deciduous canines. Correcting the disproportionate arches allows further undisturbed growth and development of maxillary bases.

Aim
The aim of the case report is to present a possibility of early orthodontictreatment of a functional unilateral crossbite in patients with deciduous dentition using the Invisalign First System.

Material and methods
A 5-year-old female patient was diagnosed with a complete unilateral crossbite on the left, due to a lateral functional mandibular shift.

Case report
The patient was treated using the Invisalign First system. Despite early detection of this malocclusion, a deciduous dentition shift secondary to the mandibular asymmetric closure path, leading to a changed shape of the lower arch, was diagnosed. Treatment involving transverse maxillary expansion that is the most commonly applied in such cases would not effectively correct and restore the proper relationship of dental arches. Therefore, a decision was made to apply treatment with the Invisalign First System as it would allow to restore normal and stable relations between the maxilla and mandible.

Summary
The applied treatment method restored proper relationships of the upper and lower dental arches and eliminated the lateral functional mandibular shift. The ability to digitally plan the appliance based on the dentition scans, and the attachments that are part of the Invisalign system, made it possible to eliminate problems associated with poor patient’s compliance and the maintenance of removable appliances on deciduous teeth.