Micropuncture measurements of interstitial fluid pressure in normal and inflamed dental pulp in cats

Interstitial fluid pressure (IFP) in cat dental pulp has been measured by glass capillaries (diameter, 2 to 4 μm) connected to a servocontrolled counterpressure system (Wiederhielm). Measurements were made in control teeth and in teeth 7 days after experimentally induced pulpitis. Control IFP averaged 5.5 (SD, 0.95) and 16.3 mm Hg (SD, 2.8) in the inflamed pulp. Measurements of IFP at a site 1 to 2 mm distant to the induced inflammation averaged 7.0 mm Hg (SD, 1.9). The measurements indicate that increased IFP due to inflammation is a local phenomenon which is not conveyed to the rest of the pulp. Increased venous pressure resulted in an immediate rise in pulp IFP whereas mannitol infusion caused a reduction in pulp IFP. The micropuncture technique for measurement of pulp IFP has the advantage of being practically atraumatic and pressure measurements are obtained rapidly, within seconds. This method allows IFP measurements at different sites in small organs, like the dental pulp.