Magnetic resonance of the articular disk in children with crossbite

Objectives: Epidemiological studies have suggested an association between unilateral posterior crossbite and temporomandibular joint (TMJ) disk displacement. The purpose of this prospective study was to investigate the articular disk positioning and its configuration in children with functional unilateral posterior crossbite (FUPXB) malocclusion and their counterparts with normal occlusion by using magnetic resonance imaging (MRI). Methods: The study sample included 9 girls and 6 boys (mean age = 9.3; standard deviaton = 2.1 y.o.) with complete unilateral posterior crossbite involving 3 or more posterior teeth and functional shift from centric relation to intercuspal position (patients group) and 10 girls and 6 boys (mean = 9.6; standard deviaton = 2.1 y.o.) with normal occlusion (control group). All participants did not have signs or symptoms of temporomandibular disorder. Sagittal and frontal TMJ MR imaging with the jaw in closed and open positions was performed bilaterally. Three of the study investigators independently interpreted the MR images. Results: No inter- or intra-group differences regarding gender were found and only one case of articular derangement (disk displacement without reduction associated with disk distortion - folded disk) was detected (patients group, same side of crossbite). Conclusion: The findings of the present study suggest that either TMJ derangements and FUPXB are independent occurrences, or the magnitude of such derangements is still not normally detected by MRI in individuals in the age range studied. Another explanation for posterior crossbite not to be reflected on disk displacement is a potential compensatory asymmetrical condyle growth and/or an articular fossa remodeling capable to hold the articular disk in position