Vertical Dimension of Occlusion (VDO) is defined as which distance?

• A. The distance between two selected points measured when the mandible is in the physiologic rest position
• B. The distance between two selected points when the mandible is in maximum intercuspation
• C. The distance between the lips when resting
• D. The distance between anterior teeth during occlusion

Answer: (A)

Vertical Dimension of Occlusion is the distance between two chosen reference points when the mandible is in occlusion, meaning the teeth are in contact and the bite is closed in centric occlusion or maximum intercuspation. This position represents the functional height of the jaw when biting and chewing, where the jaw muscles are actively supporting the occlusion.

It's important to contrast this with the rest position. In physiologic rest position, the mandible sits with minimal muscle activity and the teeth do not contact; there is a measurable freeway space, typically a few millimeters, between the teeth. That rest-position distance is called the Vertical Dimension of Rest, not the occluding dimension. The other options describe measurements that aren’t used to define VDO: the distance between lips at rest doesn’t establish occlusal height, and the spacing of anterior teeth during occlusion is not the standard reference for VDO.

So, the defining concept is that VDO is the occluding height—the distance between two reference points when the teeth are in contact in the closed bite.