[Anatomy and physiology of the periodontium in adults under the conditions of orthodontic tooth movement]

Abstract

During orthodontic tooth movement, the periodontal ligament (PDL) transduces the applied forces to the surrounding bone and is involved in the induced remodelling of periodontal fibres and alveolar bone. Due to its delicate localization between two hard tissues, the PDL is, however, prone to traumatic injuries resulting from excessive forces. With regard to the necessary remodelling processes, the adult PDL is illprepared, as all relevant physiologic cell activities, such as rate of mitosis or fibre and bone turnover, are considerably slower and have to be activated first. Furthermore, these cell activities apparently cannot be stimulated to the same level as in juvenile tissues. Thus, tooth movement, particularly in the beginning of treatment, is inevitably slower in adults than in young individuals. Any attempt to accelerate movement by applying heavier forces bears the risk of possible traumatic injuries to periodontal and root tissues.