A technique for measuring eruption rates in rats of maxillary incisors under intrusive forces.

The heads of six rats were immobilised and the position of a maxillary incisor was monitored by a displacement transducer. The weight of the central spindle of the transducer was balanced by weights applied to the far end of a pivoted bar. Intrusive forces were applied by placing weights on the near end of this bar. With opposing forces of less than 0.3 mN, the eruption rates for the six rats were between 10 and 64 μm/h, with a mean value of 34 (SD ± 16) μm/h, little more than the unimpeded eruption rate of the rat maxillary incisor.The incisor tooth pulsated in its socket.