Temporomandibular joint evaluation with magnetic resonance imaging in children with functional unilateral posterior crossbite, treated with rapid maxillary expansion.

Introduction: The purpose of this prospective study was to evaluate qualitatively articular disc position and configuration of the temporomandibular joint (TMJ) with magnetic resonance imaging (MRI) in children with functional unilateral posterior crossbite (FUPXB) treated with Haas-type orthopedic appliances.

Methods: The sample included 30 Brazilian children (60 TMJs) of both sexes (8 boys, 22 girls), aged 6.8 to 14.