In dentistry, centric relation is the
mandibular
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
jaw position in which the
head of the condyle is situated as far anterior and superior as it possibly can within the
mandibular fossa/glenoid fossa.
It is defined as, ''"The maxillo-mandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective discs with the complex in the anterior-superior position against the slopes of the articular eminences. This position is independent of tooth contact. This position is clinically discernible when the mandible is directed superiorly and anteriorly. It is restricted to a purely rotary movement about the transverse horizontal axis". — GPT.''
This position is used when restoring edentulous patients with
removable or either
implant-supported hybrid or
fixed prostheses. Because the dentist wants to be able to reproducibly relate the patient's
maxilla
The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. T ...
and mandible, but the patient does not have teeth with which to establish his or her own
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 intercusp ...
, another method has been devised to achieve this goal. The condyle can only be in the same place as it was the last time it was positioned by the dentist if it is consistently moved to the most superior and anterior position within the fossa.
It is a physiologic position that is used for reproducibility. 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. It also allows for the most repeatable and recordable position and therefore should be used when designing an appropriate occlusion.
Methods of Recording Centric Relation:
* Physiological Methods
# Tactile or inter-occlusal check record method
# Pressureless method
# Pressure method
* Functional Methods
# Needlehouse method
# Patterson method
* Graphic Methods
# Intraoral method
# Extraoral method
* Radiographic method
References
* Davis Henderson, Victor L. Steffel. McCracken's Removable partial prosthodontics, 4th Edition, 1973.
Dental anatomy
Restorative dentistry
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