Cone-Beam Computed Tomography (CBCT) Analysis of Mandibular Condyles' Diameters in Patient with Juvenile Idiopathic Arthritis and Temporomandibular Joint Affection: A Cross-Sectional Investigation

Abstract

Objectives: The aim of this study was to evaluate through analysis using CBCT the transverse and axial diameters of the mandibular condyles in subjects affected by juvenile idiopathic arthritis (JIA) and compare them with those of healthy subjects. Methods: The study was conducted on CBCT scans from the digital archive of the Department of Biomedical Surgical and Dental Sciences, University of Milan, including patients with JIA and using healthy subjects as controls. Inclusion criteria: aged between 7 and 25 years old at the time of the CBCT examination; Caucasian ethnicity; diagnosis of JIA according to the International League of Associations for Rheumatology (ILAR) criteria documented in patients' records; TMJ involvement; good quality CBCTs covering our region of interest (ROI), from the glabella to the mandibular inferior border; no previous orthodontic/orthopedic treatment; no history of craniofacial trauma or congenital birth defects involving the craniofacial area. Each CBCT scan underwent examination using 3Diagnosys^® software. Since data were normally distributed, parametric tests were used for analysis. The sample was divided into three groups: (1) bilateral JIA subjects, (2) unilateral JIA subjects, and (3) healthy controls. Results: We found a statistically significant reduction (p < 0.0001) in the transverse diameter (TR-Diam) of the affected condyles by an average of 1.7 mm, while the axial diameter (AX-Diam) again showed a slight reduction, on average by 0.1 mm, with a non-statistically significant value. Another comparison was made between the unaffected condyles of patients with unilateral JIA and the healthy condyles of the control group. The unilateral unaffected condyles were found to be slightly smaller than those of healthy patients, but without statistically significant differences. We found that in both JIA males and females, the condylar growth tends to stop earlier than the healthy ones. Conclusions: The transverse diameter was found to be more affected than the axial one, causing typical bone resorption and condylar shape. Moreover, we showed that the pathology, in the case of unilateral JIA, does not compromise only the affected condyles; the corresponding condyle that seems to be healthy is actually partially compromised. In addition, we observed that the growth of affected condyles of JIA subjects tends to stop earlier than the condyles of the healthy controls.

Keywords: CBCT; juvenile idiopathic arthritis; malocclusion; mandibular condyle; temporomandibular joint arthritis.

Figure 1

Example of the measurement’s protocols taken to assess the axial (AX_Diam) and transverse (TR_Diam) diameters: (a) slice of CBCT in which the condyle had its greatest transverse diameter in both coronal and axial projections; (b) considering the anterior and posterior poles of the condyle, the distance between these two points was measured by determining the length of the axial diameters of both condyles; (c) considering the medial and lateral poles of the condyle, the distance between these two points was measured by determining the length of the transversal diameters of the two condyles; (d) representation of both AX_Diam and TR_Diam of both right and left condyles.

Figure 2

Representation of the different trends of growth of the transverse condylar diameter (the most affected dimension) at different ranges of age in: (a) healthy males, (b) healthy females, (c) JIA males and (d) JIA females. As can be seen from the graphs, JIA patients are found to have smaller condyles in their transverse size at the same age and to have an earlier growth cessation compared to healthy condyles.