Relationship between the tooth eruption and regional blood flow in angiotensin II-induced hypertensive rats

Objective: The mechanism of action of vasoactive drugs on tooth movement is unknown. The purpose of the present study was to measure simultaneously the axial movement of the mandibular incisor, regional blood flow at the base of the incisor, and systemic arterial blood pressure in angiotensin II-induced hypertensive rats to determine the possible cause of tooth displacement. Design: The measurements were made under artificial respiration with halothane anaesthesia. In the experimental animals, 2.5 μg of angiotensin II in 1 ml of Ringer’s solution was infused at 0.83 ml/h for 12 h from the femoral vein. In the control animals, only Ringer’s solution was infused. Results: Angiotensin II caused an increase of the mean arterial blood pressure from 86 to 119 mmHg, and decreases of the eruption rate from 667 to 494 μm/24 h and the regional blood flow from 262 to 214 mV. There was a positive correlation between the eruption rate and regional blood flow, and a negative correlation between the blood pressure and regional blood flow. Conclusion: These results suggest that angiotensin II caused constriction of the peripheral vascular smooth muscle resulting in an increase of arterial blood pressure and a decrease of regional blood flow, followed by a decrease of fluid volume and then a reduction of either the pressure within the socket or of the eruptive force. We assume that the regional vascular pressure within the socket plays an important role in determining the position of the rat incisor.