The vertical dimension of occlusion (VDO), is the measurement of the relationship between the upper and lower jaw when the teeth are fully occluded in max intercuspation. VDO is sometimes referred to as vertical dimension or occlusal vertical dimension (OVD). Both patients with and without teeth possess a VDO, however, the latter is more subjective in measurement and is generally based on esthetics and phonetics, or the sound of words being pronounced as the jaw is held in the desired position. The vertical dimension of occlusion can roughly be measured by asking the patient to say “Emma.” The position of the lower jaw on the “a” sound is called the vertical dimension at rest (VDR), which is roughly 3mm greater than a patient’s VDO. Reduction of the vertical dimension of occlusion can occur after tooth loss, tooth decay, gum disease, and loss of bone in the alveolar ridge.