Fractal dimension of the condylar bone structure in patients with unilateral condylar hyperplasia: cross-sectional retrospective study

Unilateral condylar hyperplasia (UCH) is one of the causes of facial asymmetry, and it is characterized by increased growth in one of the mandibular condyles. In UCH, it is important to determine whether the metabolic activity of the hyperplastic condyle is still active. Fractal dimension (FD) analysis could be a non-invasive method to identify active metabolic activity. The aim of this study is to compare the FD of the hyperplastic condyle with the contralateral one in patients with facial asymmetry and positive bone scintigraphy and to compare the FD of the right and left condyles in symmetrical patients. A cross-sectional retrospective study of fifteen patients with facial asymmetry and positive bone scintigraphy and fifteen symmetrical patients was conducted. Clinical data and scintigraphy results were collected from medical records, and CBCT scans were used for the application of FD by pre-processing the images according to White and Rudolph and using ImageJ® (1.54p) software and the box-counting method. Wilcoxon’s t test was used to analyze the differences in FD between the hyperplastic and contralateral condyles in patients with UCH and between the right and left condyles in symmetrical patients. A p-value of <0.05 was considered statistically significant. The FD of the hyperplastic condyles was significantly higher than the contralateral one in the axial and coronal plane (p = 0.001). The analysis of FD of the mandibular condyle can be a useful non-invasive method to identify active UCH in patients with facial asymmetry.