Muscular and condylar response to rapid maxillary expansion. Part 3: magnetic resonance assessment of condyle-disc relationship.
BACKGROUND
The aim of this prospective study was to assess temporomandibular joint (TMJ) condyle-disc positions at the sagittal and coronal planes of magnetic resonance images (MRIs) before and after rapid maxillary expansion (RME).


METHODS
The study included 18 subjects (11 girls, 7 boys) with a mean age of 12.54 years with unilateral or bilateral posterior crossbite that included at least 3 posterior teeth. The clinical and radiographic assessments of the TMJ were done before (T1) and 18 weeks after (T2) RME. A Haas-type expansion appliance was used for an average treatment time of 3.5 weeks.


RESULTS
A visual MRI analysis of pretreatment condyle-disc positions showed that 8 TMJs had medial disc displacement, 3 had anteromedial disc displacement, and 2 had lateral disc displacement. The disc positions remained unchanged at T2 except in 1 subject, who developed unilateral anterior disc displacement. Unilateral joint sounds developed in 3 subjects without changes in the disc positions.


CONCLUSIONS
Posterior crossbite can be considered a minor risk factor for temporomandibular disorder (TMD). RME is neither a risk factor nor a prevention for TMD. Coronal MRIs contribute complementary information for optimal diagnosis of TMD.
Department of Orthodontics, Faculty of Dentistry, University of Toronto, Toronto, Ontario, Canada. femelarat@yahoo.com
F Emel
FE
Arat
Z Mirzen
ZM
Arat
Bryan
B
Tompson
Sumru
S
Tanju
D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D004204:Joint Dislocations / Q000209:etiology / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008310:Malocclusion / Q000150:complications* / Q000628:therapy; D008335:Mandibular Condyle / Q000473:pathology*; D008409:Mastication / Q000502:physiology; D010155:Palatal Expansion Technique; D011446:Prospective Studies; D013704:Temporomandibular Joint / Q000473:pathology*; D019224:Temporomandibular Joint Disc / Q000473:pathology*; D013705:Temporomandibular Joint Disorders / Q000209:etiology* / Q000473:pathology