Clinic Study About Protraction Of Mandibular Second Molars Into First Molar Edentulous Site In Sliding Mechanics With Miniscrew Anchorage

Objective:To investigate the change of teeth and jaws in sagittal and vertical dimensions, the distance and the velocity of the mandibular second molar moves and the change of alveolar bone in edentulous site when closing the first molar space in sliding mechanics with miniscrew anchorage. From the research some implications are got for clinical practice.Methods:Winceph 7.0 was used to measure the indexes that involve with the change of teeth and jaws, the distance and velocity of the second molar moved, as well as the change of the alveolar bone in edentulous site and root parallel. The statistical analyses were performed by using the SPSS 16.0. A paired-samples t test was used to evaluate the treatment change.Results:the velocity of the mandibular second molar was 0.85±0.36mm/m from T1 phase to T2 phase. There were significant differences in the change of alveolar bone and SN-MP, while others were not.Conclusion:Miniscrews are efficient and stable for the anchorage both in the sagittal and vertical dimensions. The remolding of the alveolar bone can increase the height of the alveolar ridge as long as the velocity and the orthodontic force are appropriate.