Periodontal ligament and alveolar bone remodeling during long orthodontic tooth movement analyzed by a novel user-independent 3D-methodology

The structural process of bone and periodontal ligament (PDL) remodeling during long-term orthodontic tooth movement (OTM) has not been satisfactorily described yet. Although the mechanism of bone changes in the directly affected alveolar bone has been deeply investigated, detailed knowledge about specific mechanism of PDL remodeling and its interaction with alveolar bone during OTM is missing. This work aims to provide an accurate and user-independent analysis of the alveolar bone and PDL remodeling following a prolonged OTM treatment in mice. Orthodontic forces were applied using a Ni-Ti coil-spring in a split-mouth mice model. After 5 weeks both sides of maxillae were scanned by high-resolution micro-CT. Following a precise tooth movement estimation, an extensive 3D analysis of the alveolar bone adjacent to the first molar were performed to estimate the morphological and compositional parameters. Additionally, changes of PDL were characterized by using a novel 3D model approach. Bone loss and thinning, higher connectivity as well as lower bone mineral density were found in both studied regions. Also, a non-uniformly widened PDL with increased thickness was observed. The extended and novel methodology in this study provides a comprehensive insight about the alveolar bone and PDL remodeling process after a long-duration OTM.