Relationship between cortical bone formation on mandibular condyles and alternation of the magnetic resonance signals characteristic of growth

Introduction: The purpose of this study was to elucidate the significance of double contour-like structures (DCLS) relative to the maturity of mandibular condyles and the possible constituents of DCLS. We evaluated the relationship between the alternation of DCLS and the ossification on the top of mandibular condyles. Methods: In 36 subjects, aged 9 to14 years at the first examination, magnetic resonance imaging characteristics of the mandibular condyles were obtained from fast spin echo intermediate-weighted images and T2-weighted images; 2 or 3 years later, magnetic resonance images were again obtained from 23 of the same 36 subjects. Results: A significant relationship was found between the absence of DCLS and the continuity of void-signal lines on the tops of the mandibular condyles. DCLS disappeared, and the void-signal lines on the tops of the mandibular condyles became continuous as the children grew. The top of DCLS was seen as a hypersignal on T2-weighted images. Conclusions: Alternations of DCLS might be a useful criterion for evaluating the maturity of mandibular condyles in children. Possible constituents of DCLS might be hypervascular loose fibrous tissue and a proliferation of cartilage accompanied by active ossification on the tops of the mandibular condyles.