The purpose of this article is to introduce an objective method for quantifying cervical dentin hypersensitivity. Air emissions from a standard air-water syringe or a syringe with a Fluid Control Block are directed toward the cervices of teeth at a 45-degree angle to the long axis of test teeth from a distance of 0.5 cm for 0.5 to 1.0 second. An air indexing method has been developed to quantify threshold patient response values for individual teeth to this defined air stimulus. The air indexing method, using the Fluid Control Block, offers the clinician objective information to compare cervical dentin hypersensitivity before and after treatment for this common, painful condition. Keywords: abfractive lesion (abfraction), air index mapping, air indexing method, cervical dentin hypersensitivity, Fluid Conlrol Block, hydrodynamic theory, threshold patient response