Microvascular pressure in the dental pulp and gingiva in cats

Pressure in selected microvessels was measured directly on the exposed coronal or apical pulp in one of the upper canine teeth or on the gingiva in a total of 36 cats. The vessels were punctured with glass micropipettes, diameter 1-4 micrometer, and the pressure measured with a modified Wiederhielm servocontrolled counter-pressure technique. Pressures in corresponding vessels in coronal and apical pulp were similar. The pressure in pulpal arterioles, diameter 10-70 micrometer averaged 43 mm Hg, or 36% of mean systemic arterial pressure (PA), while pressure in the pulpal venules, diameter 10-80 micrometer, was on an average 19 mm Hg or 16% of PA. Capillary pressure measured in the coronal pulp averaged 35 mm Hg. Mean arterial systemic pressure was 124 mm Hg. The total vascular pressure drop within the pulp was only 20% of the total systemic arteriovenous pressure difference. Accordingly, only one fifth of the vascular resistance governing pulpal blood flow is situated within the pulp itself. This means that blood flow in the dental pulp in cats may be influenced by mechanisms located extrapulpally. In gingiva only venular pressure was measured, which averaged 19 mm Hg.