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.

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.

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.

Importance of Vertical Dimension

Increased Vertical Dimension

• Increased trauma to the denture-bearing area.
• Increased lower-facial height.
• Cheek biting.
• Difficulty in swallowing and speech.
• Pain and clicking in the temporomandibular joint.
• Stretching of facial muscles.

Decreased vertical dimension

• Lesser trauma to the denture bearing area compared to increased vertical dimension.
• Decreased lower-facial height.
• Angular chelitis due to folding of the corner of the mouth.
• Difficulty in swallowing.
• Pain, clicking, discomfort of the temporomandibular joint accompanied with headache and neuralgia.
• Loss of lipfullness.
• Obstruction of the opening of the eustachian tube due to the elevation of the soft palate due to elevation of the tongue/mandible.
• Loss of muscle tone.
• Corners of the mouth are turned down.
• Thinning of the vermilion borders of the lip.
• Decreased volume or cubical space of the oral cavity.

Recording of Vertical Dimension

Vertical Dimension at Rest

It is defined as, "The length of the face when the mandible is in rest position" -GPT.

This is the position of the mandible in relation to the maxilla when the maxillofacial musculature are in a state of tonic equilibrium. This position is influenced by the muscles of mastication, muscles involved in speech, deglutition and breathing.

Vertical Dimension at rest = Vertical Dimension at occlusion + free-way space.

The following methods can be used to measure the vertical dimension at rest:

• Facial measurements after swallowing and relaxing
• Tactile sense
• Measurement of anatomic landmarks
• Speech
• Facial expression

Vertical Dimension at Occlusion

It is defined as, "The length of the face when the teeth(occlusal rims, central-bearing points, or any other stop) are in contact and the mandible is in centric relation or the teeth are in centric relation" – GPT.

The vertical dimension at occlusion is a constant position and can be maintained for indefinite time. Unlike vertical dimension at rest, the mandible need not be in centric relation while recording this relation.

Vertical dimension at occlusion can be recorded using the following methods:

Mechanical methods

• Ridge relation

1. Distance from the incisive papilla to mandibular incisors
2. Parallelism of ridges

• Pre-extraction records

1. Profile photographs
2. Profile silhouettes
3. Radiography
4. Articulated casts
5. Facial measurements

• Measurement from former dentures

Physiological Methods

1. Power point
2. Using wax occlusal rims
3. Physiological rest position
4. Phonetics
5. Aesthetics
6. Swallowing threshold
7. Tactile sense or neuromuscular perception
8. Patient’s perception of comfort