Vertical changes in the hard tissues after space closure by miniscrew sliding mechanics: a three-dimensional modality analysis

Abstract

Abstract (1)Objectives: To explore the vertical changes in the maxillary central incisor and the maxillary first molar and to investigate the changes in the mandibular plane angle during process space closure by miniscrew sliding mechanics. (2) Methods: A total of 20 adult patients were enrolled from the Department of Orthodontics of Peking University Hospital of Stomatology from 2008 to 2013. A digital dental model and craniofacial cone-beam computed tomography (CBCT) scan were taken at the beginning of the treatment(T0) and immediately after space closure(T1). Stable miniscrews were used to superimpose the maxillary digital dental models (T0 and T1), and the vertical changes in the maxillary first molar and the maxillary central incisor were measured. The changes in the mandibular plane were measured by CBCT superimposition in three dimensions. (3) Results: The average extrusion of the maxillary central incisor was 2.56±0.18 mm; the average intrusion of the maxillary first molar was 1.25±1.11 mm, with a distal movement of 0.97±0.99 mm; and the average mandibular plane angle decreased by 0.83±1.65°. The differences in the three indexes were statistically significant. (4) Conclusion: In the process of space closure with the miniscrew sliding method, the upper dentition changed significantly in both the sagittal and vertical directions. The maxillary central incisors were extruded, and the maxillary first molars were intruded. The mandibular plane was rotated slightly counterclockwise.