Experiments on the rat incisor into the cellular proliferation and blood-pressure theories of tooth eruption

Abstract

In normotensive rats, guanethidine and hydralazine in single intramuscular doses of 10 mg/kg and 8 mg/kg respectively lowered mean systolic blood pressure approximately 20 per cent. These drugs raised mean capillary pressure by approximately 20 per cent also. The effects of demecolcine, 1 mg/kg and triethylene melamine, (TEM) 0.15-0.6 mg/ kg on the dental tissues of rats with one incisor cut out of occlusion were studied by routine microscopy and by autoradiography using tritiated thymidine. Pulpal cell density was higher in incisors cut out of occlusion and radioactive nuclei were more widely distributed across the base of the pulp. Demecolcine increased the time spent in the metaphase stage of mitosis in pulp and periodontal membrane cells. TEM prevented mitotic division in pulp producing acellular areas basally and cell density of the periodontal membrane was also reduced. The rate of unimpeded eruption, measured radiographically, of the mandibular incisor of rats given guanethidine 10-20 mg/kg, hydralazine 4-15 mg/kg, or demecolcine Img/kg did not differ from control rates. Triethylene melamine in lethal doses of 0.15-0.6 mg/kg, while slowing the rate, did not stop it. It is concluded from the results that neither blood pressure nor cellular proliferation play a direct role in the process of tooth eruption. © 1966.