The true dentoskeletal changes following miniscrew-assisted molar intrusion in anterior open bite: a superimposition study on mandibular autorotation

This study quantified dentoskeletal changes, particularly mandibular autorotation, induced by molar intrusion in anterior open bite (AOB) patients. Eighteen AOB patients treated with miniscrew-assisted molar intrusion were retrospectively analyzed. Dental and skeletal changes were assessed using structural and cranial base superimpositions to isolate true autorotational effects. Statistical analysis included independent t-tests, Pearson or Spearman correlations, and linear regression. The mean total molar intrusion (TMI) was 1.45 ± 1.03 mm. This produced a true vertical displacement of the lower incisor (TVD-L1) of − 1.93 ± 1.03 mm, showing a correlation with TMI (R = − .82, p < .001). Menton moved upward (ΔHRP-Me) by − 1.62 ± 0.99 mm and was correlated with TMI (R = − .86, p < .001). The mandibular plane angle (ΔSN-MP) decreased by − 1.32 ± 1.13°, and forward movements were observed at Pogonion (ΔVRP-Pog) of 1.58 ± 1.58 mm and at the lower incisor (THD-L1) of 0.81 ± 1.13 mm; however, these changes were not correlated with TMI (p > .05). Larger ΔSN-MP values were associated with ΔVRP-Pog (R = .65, p = .004) and THD-L1(R = .49, p = .038). The predictive equations for TVD-L1 and ΔHRP-Me were TVD–L1 = − 0.970–0.665 × TMI (R² = 0.441) and ΔHRP–Me = − 0.509–0.768 × TMI (R² = 0.636). Molar intrusion effectively induces mandibular autorotation, resulting in favorable vertical corrections. While vertical changes were proportional to the amount of intrusion, horizontal movements followed a more complex pattern, depending on mandibular plane changes rather than TMI alone.