Assessment of right-left differences in trabecular bone structure within the maxillary lateral incisor-canine region...

Maxillary lateral incisor agenesis, peg-shaped lateral incisors, impacted canines, and cleft lip and palate frequently involve the maxillary lateral incisor-canine region and often show side-related distribution patterns. Whether trabecular bone structure within this region differs between sides in clinically healthy individuals remains unclear. This study evaluated right-left differences in maxillary trabecular bone structure using fractal analysis.

Panoramic radiographs of 88 adults (43 males, 45 females; 18-40 years) with Class I occlusion and no dental, skeletal, or orofacial anomalies were retrospectively analyzed. Bilateral polygon-shaped ROIs were defined between the maxillary lateral incisor and canine roots. As methodological validation, standardized 20 × 20 pixel square ROIs were additionally analyzed. FD values were calculated using the ImageJ box-counting method. Inter-observer reliability was assessed by two independent oral and maxillofacial radiologists using the intraclass correlation coefficient (ICC) and Dahlberg error. Right-left comparisons were performed using paired-samples t-tests or Wilcoxon signed-rank tests. Associations with age and sex were also evaluated.

Using anatomically defined freehand ROIs, FD values were significantly higher in the left maxillary region than in the right (0.77 ± 0.23 vs. 0.70 ± 0.25; mean paired difference = 0.07, 95% CI: 0.01-0.13; p = 0.024; Cohen's d_z​ = 0.24). The same direction of the right-left difference was confirmed using standardized square ROIs. No significant right-left differences were found for ROI area (p = 0.229), mean gray value (p = 0.618), minimum gray value (p = 0.682), or maximum gray value (p = 0.708). The right-left FD difference was not associated with age or sex.

A small but statistically significant right-left difference in FD values was detected within the maxillary lateral incisor-canine region. Although the effect size was small and the biological significance remains uncertain, consistent findings across two ROI approaches together with excellent inter-observer reproducibility support the methodological consistency of the proposed protocol. The findings should be interpreted as a subtle radiographic observation rather than as definitive evidence of physiological maxillary asymmetry.

Not applicable.