Computed Tomography (CT)-Assisted 3D Cephalometry in Horses: Interincisal Angulation of Clinical Crowns.
Authors: Kau Silvio, Failing Klaus, Staszyk Carsten
Journal: Frontiers in veterinary science
Summary
# Editorial Summary Understanding how incisor angles change with age has long been considered useful for equine age assessment, yet previous approaches treated all incisors as a single unit without accounting for individual tooth positioning. Kau and colleagues used computed tomography and 3D reconstructions to measure the interincisal angulation of clinical crowns in 48 horses, developing precise landmarks based on the labial axis of each tooth rather than relying on two-dimensional profile views. Their measurements proved highly reproducible (mean variation of only 0.65%), and revealed that angle decline follows a non-linear pattern—steeper in younger horses and plateauing with age—with third incisors showing significantly more angular change than first or second incisors (P < 0.0001). Notably, the researchers found such variability between tooth positions that age determination using clinical crown angulation alone is unreliable and should not be relied upon clinically. For equine practitioners, this work demonstrates that 3D cephalometric analysis offers genuine value for assessing individual tooth relationships in both health and disease, suggesting that more sophisticated imaging approaches may be warranted when detailed dentofacial assessment is needed rather than relying on traditional visual estimation methods.
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Practical Takeaways
- •Do not rely on incisor angulation alone for age determination in horses—the relationship with age is too variable between tooth positions and individual horses
- •If performing detailed dentofacial assessments, 3D CT imaging provides precise measurements of individual tooth positions that 2D radiographs cannot capture
- •Third incisors show distinctly different wear and angulation patterns compared to first and second incisors, suggesting they may require separate assessment in diagnostic or therapeutic planning
Key Findings
- •3D CT cephalometry using labial axis of clinical crown (LACC) measurements demonstrated high reproducibility (mean coefficient of variation = 0.65%) for determining interincisal angulation across all incisor positions
- •Third incisor teeth showed significantly greater angle decline with age compared to first and second incisors (P < 0.0001), with non-linear rather than linear decline pattern
- •Angle decline was more pronounced in younger horses and appears to plateau in older horses, making age determination by incisor angulation unreliable
- •3D CT cephalometry is more reliable than traditional 2D lingual/palatal border measurements for assessing specific tooth positions, showing two-fold lower measurement dispersion