Fractal dimension analysis of mandibular and cervical regions across hand–wrist maturation stages

Abstract

This study evaluated whether fractal dimension (FD) values from mandibular regions and cervical vertebrae on routine panoramic and lateral cephalometric radiographs differ across seven hand–wrist maturation stages in adolescents, using hand–wrist staging as the reference standard, and whether these values are associated with maturation stage and sex. This retrospective cross-sectional study included 105 adolescents aged 8–17 years with hand–wrist, panoramic, and lateral cephalometric radiographs taken on the same day. FD values were calculated from six 40 × 40-pixel regions of interest using a standardized ImageJ box-counting method. Inter-rater reliability was assessed using intraclass correlation coefficients, and correlations and group comparisons were performed with Holm correction for multiple testing across the six anatomical regions. After Holm correction, hand–wrist maturation stage showed significant positive correlations with FD at the mandibular symphysis, second cervical vertebra (C2), and third cervical vertebra (C3). Significant stage-related differences remained for the mandibular symphysis and C2, whereas no significant sex-related differences remained after multiple-testing correction. In multivariable analyses adjusted for age and sex, maturation stage remained significantly associated with FD at the mandibular symphysis and C2. These findings suggest that FD at the mandibular symphysis and C2 may reflect maturation-related trabecular changes; however, their clinical and diagnostic utility requires further validation.