Abstract
This retrospective study quantitatively evaluated mandibular incisor intrusion and associated vertical skeletal changes during deep-bite correction using Invisalign clear aligner therapy. Twenty-seven adult patients (19-54 years of age) with skeletal Class I or II malocclusion and deep overbite (> 3 mm) treated with Invisalign incorporating precision bite ramps were retrospectively analyzed. Lateral cephalometric radiographs obtained before (T0) and after treatment (T1) were superimposed on the cranial base and mandible. Mandibular incisor movement was assessed using centroid-based measurements to isolate pure intrusion and minimize the influence of tipping. Changes in the occlusal plane angle, mandibular plane angle (FMA), incisor mandibular plane angle (IMPA), and molar vertical position were also evaluated. Paired t-tests were performed for statistical comparisons. The mandibular incisor centroid demonstrated statistically significant pure intrusion of 1.63 mm (p < 0.001). Occlusal plane angle increased significantly (mean change: 2.38°, p = 0.001) and overbite decreased (mean change: -1.98 mm, p = 0.001), whereas changes in the FMA, IMPA, and mandibular molar extrusion were not statistically significant, suggesting limited vertical skeletal changes during treatment. These findings suggest that Invisalign therapy with precision bite ramps demonstrated mandibular incisor intrusion in adult deep-bite patients.