Dentinal hypersensitivity is discomfort (sharp, shooting, or stabbing pain) caused by exposed dentin and open dentinal tubules (often due to gingival recession). The open dentinal tubules permit rapid fluid movement inside the tubules that subsequently stimulate pulpal mechanoreceptors. Dentinal hypersensitivity most commonly affects the buccal surfaces of premolars (but can occur on any tooth). Causes include overzealous toothbrushing, periodontal disease, acidic diet, GERD, and xerostomia. Treatment involves occluding (blocking) the open dentinal tubules orifices with glass ionomer or CPP-ACP varnish to physically prevent pulpal hyper-stimulation.