Volumetric Symmetry of Maxillary Tooth Roots: A Cone Beam Computed Tomography Based Study Using Manual-Assisted Segmentation.

Objective

To evaluate bilateral symmetry in root volume, length, mesiodistal (M/D) and buccopalatal (B/P) widths of maxillary permanent teeth anterior to the first molars.

Materials And Methods

This cross-sectional study analyzed CBCT data from 189 subjects (93 males and 96 females) with mean age 38.18 ± 8.08 years. Inclusion criteria required fully developed apices and no history of trauma, orthodontic treatment, or craniofacial anomalies. One investigator performed manual-assisted segmentation on 1,202 maxillary incisors, canines, and premolars. Root volume (mm3) root length (mm), M/D width (mm), and B/P width (mm) were measured. A linear mixed-effects model assessed bilateral symmetry.

Results

Males exhibited significantly greater root dimensions than females across all measured parameters (p < 0.001). After adjusting for biologic sex and tooth type, no significant main effect of side was observed for root volume (p = 0.196), root length (p = 0.714), or bucco-palatal root width (p = 0.381). A potential side effect was observed for mesiodistal root width (p = 0.014), although this did not meet the prespecified significance threshold of p < 0.01.

Conclusions

Maxillary root dimensions differ by sex, with no statistically significant side effects for root volume, length, or bucco-palatal and mesio-distal widths. For root length, equivalence testing did not establish equivalence within the prespecified ±0.20-mm margin. Clinical research using symmetry should consider stratifying data by sex to ensure that sex-related anatomical differences are not mistaken for clinical pathology. Ultimately, this study provides a valuable baseline knowledge of symmetry that can be used in future research.