Disc position in clinically asymptomatic, pretreatment adolescents with Class I, II, or III malocclusion : A retrospective magnetic resonance imaging study.

Abstract

To test the null hypothesis that children with Class I, II, and III malocclusions who have not undergone orthodontic therapy present with displaced discs. This study relied on retrospective material consisting of 76 unilateral left sagittal-oblique temporomandibular joint (TMJ) magnetic resonance imaging (MRIs) and lateral cephalometric radiographs taken in maximum intercuspal position in patients with clinically symptom-free and orthodontically untreated Class I (n=30; 19 girls and 11 boys), Class II (n=26; 10 girls and 16 boys), and Class III malocclusion (n=20; 5 girls and 15 boys). The mean ages of patients with Class I, II, and III malocclusions were 10.55±0.81, 11.71±0.31, and 8.98±1.80years, respectively. Study groups were compared with one-way ANOVA analysis or Welch ANOVA test. Differences were evaluated via the Tukey HSD or Games-Howell test. Disc-condyle positions were almost within normal limits in Class I malocclusion. The disc was positioned anteriorly relative to the condyle (p<0.05) and the condyle positioned posteriorly in the glenoid fossa in Class II malocclusion (p<0.05). The disc was positioned slightly anteriorly relative to the condyle (p<0.05) and the condyle was positioned posteriorly in the glenoid fossa in Class III malocclusion. Disc-condyle positions were observed to be almost identical in all three malocclusion classes. Disc-condyle position was nearly normal in patients with Class I malocclusion. Nevertheless, a Class II malocclusion is more apt to reveal anterior disc displacement than a Class III malocclusion.