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 want to be able to reproducibly relate the patient's maxilla and mandible, but the patient does not have teeth with which to establish his or her own vertical dimension of occlusion, 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.
Centric relation is an old concept in dentistry based on an old mechanical viewpoint of dentistry. There are over 26 different definitions of Centric Relation since the term was first developed as a starting point for making dentures. It is a physiologic position that is used for reproducibility. The Temporomandibular Joint, is not restricted to Centric Relation in function. Long centric is a term that describes a functional position that patients restored in Centric Relation frequently migrate to.
Centric Relation believers state that the relationship of the mandible to the maxilla when the properly aligned condyle-disc assemblies are in the most superior position against the eminentiae irrespective of Occlusal Vertical Dimension (OVD) or tooth position.
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 methd.
- Extraoral method.
- Radiographic Method.
- Davis Henderson, Victor L. Steffel. McCRACKEN's Removable partial prosthodontics, 4th Edition, 1973.
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