Short-term extrusion of isolated teeth of adult monkey (Macaca fascicularis).

By means of a variable capacitance device, the occlusal movements of 12 fully-developed teeth were recorded in 6 adult monkeys. Sustained extrusion was seen, with rhythmic pulsations due to the heart beat and to breathing. Extrusion varied from 10 to 138 micrometers over periods of 40-360 min, and became progressively slower with time. Because of the protracted nature of the extrusion, it is probable that these tooth movements were caused by forces generated in the periodontal ligament resulting from biochemical changes in the periodontium rather than by vascular alterations, and occurred as a result of the removal of intrusive loads from the opposing teeth.