Effects of orthodontic treatment with fixed functional orthopaedic appliances on the disc-condyle relationship in the temporomandibular joint: a magnetic resonance imaging study (Part II)

Abstract

Objectives: This study aimed to verify the effects that corrective treatment for skeletal Class II malocclusions with fixed functional orthopaedic appliances has on the relative positions of the articular disc and the mandibular condyle.

Methods: Orthodontic treatment progress was monitored in 20 patients by magnetic resonance imaging (MRI) at four defined points in time. Visual inspection of the temporomandibular joints (TMJs) was performed on three slices each (lateral, central, medial) of closed-mouth and maximum-open parasagittal MRI. Metric analysis was performed on the central slices of the images obtained in the closed-mouth position. To assess the positional relationship in the sagittal dimension between the articular disc and the mandibular condyle, both methods were used.

Results: The comparison of pre-treatment and post-treatment findings revealed in none of the joints that the disc-condyle relationship had been adversely affected as a consequence of the treatment. Rather, the outcome was an improved relationship in a total of eight joints. After groups of joints had been defined by disc position, metric analysis revealed a significantly improved positional relationship in those joints in which an anterior disc displacement had been found initially.

Conclusion: Orthodontic treatment with a rigid, fixed functional appliance to correct skeletal distoclusion results in the following side effects on the disc-condyle relationship in the TMJ: the treatment does not have adverse effects on initially physiological disc-condyle relationships; in TMJs with initial partial or total anterior disc displacement, improved disc position can be achieved.