Signs, Symptoms, and Morphological Features of Idiopathic Condylar Resorption in Orthodontic Patients: A Survey-Based Study

Abstract

Background: Idiopathic condylar resorption (ICR) is an aggressive degenerative disease of the temporomandibular joint that is most frequently observed in teenage girls. However, no specific cause of ICR has been identified. To explore the specific causes of the onset and progression of ICR, we performed a survey-based study on ICR in orthodontic patients and described its subjective symptoms, clinical signs, and condylar morphological features.

Methods: A total of 1735 participants were recruited from 2193 orthodontic patients. For each participant, subjective symptoms and clinical signs of temporomandibular disorders (TMDs) were evaluated through clinical examination and a questionnaire. Furthermore, three-dimensional computed tomography (CT) was performed to diagnose ICR.

Results: Among the 1735 patients evaluated, ICR was present in two male and ten female patients. All 12 patients had maxillary protrusion and an anterior open bite. Four patients with ICR underwent orthodontic treatment. Based on CT findings, patients with ICR had significantly different condylar sizes and shapes from patients with TMDs alone.

Conclusions: The coexistence of intrinsic and extrinsic factors, such as sex-hormone imbalance and a history of orthodontic treatment, might lead to the onset of ICR. We suggest that growing patients suspected of having ICR should undergo CT evaluation because CT findings may precede clinical symptoms and signs.

Keywords: idiopathic condylar resorption; orthodontic patients; orthognathic surgery; progressive condylar resorption; temporomandibular disorders.

Figure 1

Three-dimensional CT images and the definitions of the measurement items. (A) Sagittal view showing condylar length measurement between ACo and PCo, and condylar height as distance from SCo to R-tan-P. (B) Coronal view showing condylar width measurement between LCo and MCo. ACo, anterior-most condylar point; PCo, posterior-most condylar point; SCo, superior mandibular condyle; R-tan, a tangent to the posterior surface of the ramus at the deepest point of the mandibular incisura; R-tan-P, a line perpendicular to R-tan; LCo, lateral condylar point; MCo, medial condylar point.

Figure 2

Axial 3D CT image showing the condylar axial angle between the condylar axis (LCo-MCo) and the midsagittal reference line (N–B). LCo, lateral condylar point; MCo, medial condylar point; N–B, Nasion–Basion.