[The age dependence of the tissue reaction in tooth movements]

Factors are indicated that influence orthodontic tooth movement and vary with age of life. During a first phase, tooth movement is characterized through biomechanical properties of the periodontal ligament and alveolar bone, while during a second phase, through kind and extent of disturbance of periodontal blood circulation. During a third phase of tooth movement, remodelling and repair is determined by cellular kinetics, synthesis, and mineral turnover. Reports in the literature and our own experimental findings are interpreted. In conclusion, in middle aged patients the remaining biological possibilities for tooth movement are decreased to about one third of those to be found in infants.