Influence of panoramic image acquisition and digitization methods on fractal dimension measurement in panoramic...

Fractal dimension (FD) analysis is widely used as a quantitative radiographic method to characterize structural complexity in mandibular bone. However, FD measurements may be influenced by image acquisition and digitization procedures, potentially affecting comparability across imaging modalities. The effect of camera-digitized conventional panoramic radiographs on FD analysis remains insufficiently investigated. This study aimed to evaluate the influence of panoramic image acquisition methods on mandibular FD values by comparing camera-digitized conventional panoramic radiographs with digital panoramic radiographs.

This cross-sectional study included 252 panoramic radiographs obtained from adults aged 25-75 years, consisting of 126 camera-digitized conventional and 126 digital panoramic radiographs. Fractal analysis was performed using the box-counting method on 11 mandibular regions of interest (ROIs) representing trabecular and cortical bone areas. FD measurements were analyzed according to imaging modality, bone microstructure type, age group, and sex. Interobserver and intraobserver reliability were evaluated using the intraclass correlation coefficient (ICC). Statistical analyses included multivariate analysis of variance (MANOVA), paired-samples t-tests, and Wilcoxon signed-rank tests, with a significance level of p < 0.05.

FD values differed significantly between imaging modalities across all ROIs (Wilks' Lambda, p < 0.001), with higher FD values observed in camera-digitized conventional panoramic radiographs. Trabecular bone demonstrated significantly higher FD values than cortical bone (p < 0.001). Limited and inconsistent differences were observed across age and sex groups. Excellent intraobserver and interobserver agreement was achieved (ICC > 0.90). Therefore, the observed differences should be interpreted primarily as variability in FD measurements associated with imaging methods rather than direct evidence of differences in mandibular bone microarchitecture.

Panoramic image acquisition and digitization methods significantly influence mandibular FD measurements. Camera-digitized conventional panoramic radiographs consistently demonstrated higher FD values than digital panoramic radiographs, indicating that FD measurements are sensitive to imaging-related variability. The observed FD variability likely reflects a combination of biological variation and technical influences associated with image acquisition, digitization, and image processing. These findings emphasize the need for standardized image acquisition and digitization protocols to improve the reliability, reproducibility, and comparability of FD analysis, particularly in retrospective studies using archived radiographs.