Orthodontic tooth movement into jaw regions treated with synthetic bone substitute.

INTRODUCTION Orthodontic tooth movement is fraught with risks and complications. Root resorption is the most frequent and important outcome which may arise due to inappropriate force magnitude or tooth movement into dense or altered bone. This study was aimed to demonstrate histologic changes in tooth roots following movement into a jaw region treated with synthetic bone substitute. Another objective was to evaluate the method of experimental tooth movement using an animal model. MATERIAL AND METHODS One mandibular premolar was extracted in each of three pigs (Sus scrofa domesticus). The extraction alveolus was filled with synthetic bone substitute material and a orthodontic appliance was attached for 90 days. The force for tooth movement was in the range of 1-2 N. Subsequently, specimens were collected using segmental osteotomy and were prepared histologically. Unmoved teeth served as controls. RESULTS Histological analysis showed clear lacuna-like lesions in the root surface area of all specimens. The lesions were largest in the apical area, while the mid-root region was less affected. CONCLUSIONS Due to deformations of the orthodontic tooth moving appliance, the force could not be exactly defined. Therefore, marked resorption lesions of the root surfaces cannot be unequivocally attributed to the synthetic bone substitute. However, the type of lesions on root surfaces permits the assumption that orthodontic tooth movement into areas filled with synthetic bone substitute may be associated with an increased risk of root resorption.