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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 ...
The vertical jaw abnormalities relating to the mandible are in relation to excessive vertical growth and excessive horizontal growth, measured by the maxillary-mandibular plane angle (MMPA). The vertical jaw abnormalities relating to the maxilla are in relation to excessive downward displacement (EDD) and insufficient downward displacement (IDD).
This is an important jaw position, as it defines both the anterior-posterior and lateral relationships of the mandible and the maxilla, as well as the superior-inferior relationship known as the vertical dimension of occlusion. These are important considerations in orthodontic treatment as well as for dental prostheses and their design and use.
Centric relation describes a reproducible jaw relationship (between the mandible and maxilla) and is independent of tooth contact. This is the position in which the mandibular condyles are located in the fossae in an antero-superior position against the posterior slope of the articular eminence . [ 12 ]
During translation, the condylar heads slide anterior and inferiorly down the articular eminence, [14] allowing the jaw to open wider. This path of movement is the line produced between 'R' and 'T', where 'T' indicate the maximal jaw opening with full translational movement.
The Temporomandibular Joint is not restricted to Centric Relation in function. At the most superior position, the condyle-disc assemblies are braced medially, thus centric relation is also the midmost position. A properly aligned condyle-disc assembly in centric relation can resist maximum loading by the elevator muscles with no sign of discomfort.
When measuring the vertical range of motion, the measurement must be adjusted for the overbite. For example, if the measurement from the edge of the lower front teeth to the edge of the upper front teeth is 40 millimeters and the overbite is 3 millimeters, then the jaw opening is 43 millimeters. During jaw movements, only the mandible moves.
Increased vertical growth causes a long facial profile and commonly leads to an open bite malocclusion, while decreased vertical facial growth causes a short facial profile and is commonly associated with a deep bite malocclusion. However, there are many other more common causes for open bites (such as tongue thrusting and thumb sucking) and ...