ORTHODONTICS AND TEMPOROMANDIBULAR-JOINT INTERNAL DERANGEMENT

The purpose of this investigation is to compare the prevalence of inte rnal derangement of the temporomandibular joints (TMJ) in asymptomatic volunteers versus symptomatic subjects using magnetic resonance imagi ng (MRI), with a detailed comparison to clinical signs and symptoms an d with attention to a prior history of orthodontic treatment. Bilatera l MRI scans were obtained of the TMJs in 76 asymptomatic volunteers an d 102 symptomatic patients. A comparison was made to the clinical sign s and symptoms, a history of orthodontic treatment, and to the MR find ings. The MRI scans were reviewed using established criteria for disk displacement and the reviewers were blinded as to the clinical informa tion. Our results show a prevalence of disk displacement in 25 of 76 ( 33%) volunteers and 79 of 102 (77%) patients with a statistically sign ificant difference (p < 0.001). No statistical link was noted between a history of prior orthodontic treatment and internal derangement of t he TMJ.