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

Abstract Background This study quantified dentoskeletal changes, particularly mandibular autorotation, induced by molar intrusion in anterior open bite (AOB) patients. Methods 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. Results 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). Conclusions 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.