Incisor growth acceleration after lesions in the lateral pontine reticular formation of rats.

The length of upper and lower incisors of Long-Evans hooded rats between gingiva and top were measured before and after small bilateral symmetric electrolytic lesions of the pontine reticular formation between the ventromedial parabrachial nucleus and the motor trigeminal nucleus. Ten days after lesions of this region 8.5 mm posterior to bregma the length of upper incisors was 13.4 +/- 0.7 mm compared with 6.1 +/- 0.2 mm before lesion (p less than 0.01) and the length of the lower incisors 17.1 +/- 0.4 mm compared with 10.2 +/- 0.2 mm before lesion (p less than 0.01). A second group with a smaller lesion of this region 9.0 mm posterior to bregma reached upper incisor length of 13.2 +/- 0.4 mm (p less than 0.05) and lower incisor length of 14.7 +/- 0.5 mm (p less than 0.05) at the 20th postoperative day. Sham-operated controls had no tooth growth acceleration.