[Periodontal reaction to orthodontic measures].

In twelve rats, the right maxillary first molar was moved mesially by means of a fixed appliance. It was not possible to find any histopathological differences with forces of 10 N, 20 N and 30 N. We also found no different cellular reactions in the tension and pressure zones between the periods of three, six, ten and 14 days. In the treated rats the first molar was tilted. The mesial root was intruded. Local pressure zones were regularly formed around the mesial root and distal aspect of the alveolar crest of the bifurcation. It could be shown by vital polyfluorochrome staining that there was no mesial tooth movement; rather distal drifting was delayed.