Developing a reference MRI database for temporomandibular joints in healthy children and adolescents.

backgroundRecognition of normal temporomandibular joints (TMJs) is essential to assess arthropathic changes. Few, if any, prior studies have evaluated the morphological appearance of growing TMJs by magnetic resonance (MR) examinations in the pediatric population.

objectiveThis study aimed to determine normative osseous appearance of growing TMJs according to age and gender, both qualitatively and quantitatively, concerning structural and bone marrow changes. MATERIALS AND

methodsFrom 1,036 MR scans screened, one joint was included from each of 157 patients (76% female; 2-18 years) presenting with at least one normal-appearing TMJ was included. Quantitatively, mandibular condyle was characterized by measuring the following: (i) head-neck angle, (ii) anteversion angle, (iii) condylar dimensions (mediolateral, craniocaudal and anteroposterior [AP]) and (iv) condylar volume. Furthermore, qualitative categorization of condylar shape, into one of three types, and condylar bone marrow type was performed.

resultsThe head-neck angle significantly correlated with age (bivariable regression β =0.60, P<0.001), indicating an increase of 1.6 degrees per year. Except for AP diameter of condyles, all other mandibular dimensions and condylar volume increased with age (β =0.20-0.59, P≤0.001-0.004). Significant age difference was observed among the different condylar shapes (P<0.001), indicating a change from rounded head without anterior tilt to rectangular head with anterior tilt. Lastly, mandibular condylar size, measured by volume and by AP and mediolateral dimensions, appeared larger in males.

conclusionThe morphology of the mandibular condyles changes with age. During development, the shape of the condyles changes from round to rectangular in contour with the development of the anterior condylar tilt, as measured by the head-neck angle.