Fractal Dimension as a Tool for Mid-palatal Suture Maturation Assessment- A Cone Beam Computed Tomography Study

Background:Rapid maxillary expansion (RME) is used for correcting transverse discrepancies by splitting the mid-palatal suture (MPS), but the amount of skeletal expansion varies with MPS maturation and qualitative staging systems are subjective. The primary aim of this study is to quantify the FD values across MPS stages in a South Indian cohort and to correlate FD with MPS, cervical vertebral maturation stages (CVM) stages and age.Methods:This observational study analysed 50 CBCT scans of patients aged between 8–20 years. A standardized region of interest (ROI) along the MPS was processed in ImageJ software via the box-counting method for assessment of the FD. MPS stages A–E and CVM stages 1–6 was assessed. Statistical analyses included one-way ANOVA with Scheffé post hoc tests, Spearman’s correlation, ROC curve analysis, Intra-class correlation co-efficient (ICC) for FD reliability, and weighted κ for staging reproducibility.Results:FD correlated strongly with MPS stage (r= –0.966), CVM stage (r= –0.928), and age (r= –0.883; all p < 0.001). ROC analysis yielded an AUC of 0.997. The FD value cut-off of 1.03 achieved 75% sensitivity and 100% specificity for distinguishing early (A–C) versus late (D–E) maturation of the MPS. Intra- and inter-rater ICCs for FD were 0.78 and 0.71, respectively; weighted κ values for MPS and CVM staging ranged from 0.73 to 0.82.Conclusion:Fractal analysis provided a quantitative, reproducible measure of MPS maturation. An FD threshold of 1.03 reliably differentiates early (A-C) and late (D-E) MPS stages and correlates with CVM stage and chronological age, offering a valuable adjunct to conventional qualitative assessments for optimizing RME timing.Key Words: Cone beam computed tomography, Fractal analysis, Maxilla, Palatal expansion, Orthodontics.