Measurement and Definition of VDO
- VDO can be measured subjectively based on esthetics and phonetics for completely edentulous patients.
- Maxillary and mandibular record bases with notched wax rims are used to record a measured VDO.
- Wax rims are built up or removed until the appropriate VDO is established.
- The notched wax rims allow an index of the relationship between the maxillary and mandibular rims.
- Alluwax or Regisal can be used as a medium for the index.
- VDO, or vertical dimension of occlusion, indicates the superior-inferior relationship of the maxilla and mandible in maximum intercuspation.
- VDO can be measured subjectively for completely edentulous individuals.
- It is not only possessed by people with teeth.
- VDO is important for proper dental occlusion and function.
- Loss of vertical dimension can occur due to tooth decay and loss.
Esthetics of VDO
- An appropriately measured VDO will appear ordinary in terms of the configuration of the nose, lips, and chin.
- Excessive VDO can make it difficult for the patient to close their lips and may give the appearance of something stuffed in their mouth.
- Straining to close lips around wax rims during VDO determination can indicate excessive VDO.
- Deficient VDO can cause the mouth to appear collapsed and the chin too close to the nose.
- Insufficient wax on the rims can lead to over-closing of the mouth.
Phonetics and VDO
- Sibilant and fricative sounds are commonly used to establish a patient's VDO.
- Sibilant sounds involve nearly touching the maxillary and mandibular incisors.
- Fricative sounds involve the maxillary incisors touching the slightly inverted lower lip at the wet-dry line.
- Counting upwards from fifty and then sixty can help determine the appropriate VDO based on the patient's attempts to make fricative and sibilant sounds.
- Saying the name 'Emma' can provide a rough estimate of the patient's VDO, known as the vertical dimension at rest (VDR).
Practical methods for finding VDO
- The distance between the inner corner of the eye and the corner of the lips can be used to find a suitable VDO.
- This measurement is applied between the center bottom of the nose and the lower tip of the mandible center.
- In completely edentulous individuals, adjustments should be made accordingly.
- Maintaining a centric position is important when determining VDO.
- Practical methods can be used to estimate VDO in the absence of specific measurements.
Additional Information
- Alluwax or Regisal can be used as a medium for the index in measuring VDO.
- Loss of vertical dimension can occur due to tooth decay and loss.
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.
A VDO is not only possessed by people who have teeth, however; for completely edentulous individuals who do not have any teeth with which to position themselves in maximum intercuspation, VDO can be measured based on subjective signs related to esthetics and phonetics.
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. An excessive VDO will appear as though the patient has something stuffed into their mouth, and the patient may not even be able to close their lips. A telltale indication of an excessive VDO is a patient straining to close their lips around the wax rims during VDO determination. 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. The two sounds most commonly used to establish a patient's VDO are sibilant and fricative sounds. Sibiliant sounds are made by allowing the maxillary incisors to nearly touch the mandibular incisors, while fricative sounds are made by allowing the maxillary incisors to touch the slightly inverted lower lip at the wet-dry line. By having the patient count upwards from fifty and then upwards from sixty, the dentist can watch and listen to the patient attempting to make first fricative and then sibilant sounds and adjust the wax rims accordingly.
A common trick is to ask the patient to say the name "Emma," as the position of the mandible immediately after completing the word is a rough estimate of the patient's proper VDO. The position after saying "Emma" is referred to as the vertical dimension at rest, or VDR. Historically, the VDO has been estimated at 3 mm less than VDR because a person will generally maintain their mandible at an opening of 3 mm when at rest.
There is another rule that applies to many mammals which give us a very practical way to find a suitable VDO. Take the distance between the inner corner of the eye and the same corner of the lips (in older people the measurement should be done a little more medially (closer to the nose) to avoid a down-pointing lip corner). Using a ruler, apply this measurement between the center bottom of the nose (that rises from the upper lip) and lower tip of the mandible center. (In the completely edentulous (those with no teeth), do as referred.) Maintain a centric position.
