Vertical dimension of occlusion

Vertical dimension of occlusion, or VDO, also known as occlusal vertical dimension (OVD), is a term used in dentistry to indicate the superior-inferior relationship of the maxilla and the mandible when the teeth are occluded in maximum intercuspation.

In terms of esthetics, an appropriately measured VDO will appear to a layman's eye as an ordinary configuration of the patient's nose, lips and chin.

Conversely, a deficient VDO will appear as though the patient's mouth has collapsed, and the chin appears too close to the nose; in essence, the patient would be over-closing their mouth because there would not be enough wax on the wax rims to maintain the proper vertical dimension of occlusion.

In terms of phonetics, certain sounds are made by configuring the mouth in specific ways.

[2] There is another rule that applies to many mammals which give us a very practical way to find a suitable VDO.

A patient prepared for measurement of VDO. Two stickers have been affixed to her face in order to establish the distance between the dots drawn on the stickers when her mandible is in a position that matches her VDO. Because this patient is completely edentulous (has no teeth), her VDO measurement will be subjectively based on esthetics and phonetics.
Maxillary and mandibular record bases with notched wax rims . When placed in the mouth, these two preliminary appliances will be able to record a measured VDO because the patient will be unable to close further than the wax will allow. The wax is built up or removed until the appropriate VDO has been established. The two wax rims are then notched in order to allow an index of the relationship of the maxillary rim to the mandibular rim with a medium, such as Alluwax or Regisal.
Loss of vertical dimension due to tooth decay and loss.