<p>Participant characteristics (n = 80).</p>

Labial bone was thinner than lingual bone (all P < 0.001), and labial thickness was below 0.5 mm in 80.3% of cervical and 63.4% of middle-root observations. Signed IA-PAMD correlated positively with labial apical thickness, negatively with lingual apical thickness, and not with total apical width. In adjusted models, each 1° increase in signed IA-PAMD was associated with 0.084 mm greater labial apical thickness (95% CI, 0.053–0.115), 0.092 mm lower lingual apical thickness (95% CI, −0.141 to −0.043), and no difference in total apical width (−0.008 mm; 95% CI, −0.082 to 0.065).

The mirror-image labial and lingual coefficients, together with the near-zero total-width coefficient, support interpretation of signed IA-PAMD as a measure of root-apex eccentricity within the symphysis rather than aggregate apical bone support. It should not be interpreted as a treatment target or safety threshold, and the absence of a Class I comparator limits conclusions specific to skeletal Class III morphology.</p></div>