Manuals_files/CD Manual 12.pdf - Removable Prosthodontics

Maxillo-mandibular Relationships - 32
11. Adjust a cast support under the bite fork
12. Mix fast set or mounting plaster to a creamy consistency - apply to ring and wet cast
surface
13. Close the articulator. Once set, remove the ring and cast and add mounting stone to make
the mounting smooth and neat.
Centric Position
A centric position is an acceptable reference position for complete denture treatment that is:
1. Conducive to health - not pathogenic
2. Relatively repeatable - so the patient can find stable occlusal contacts easily
3. A hinge position - allows change in the vertical dimension easily and so the patient
can find stable occlusal contacts easily
4. A relatively symmetrical position - avoids muscle strain which might occur in
excursive positions
Many prosthodontic and occlusion textbooks use the term “Centric Relation” (CR) to
define the position that the mandible should take in relation to the maxilla for the purpose
of arranging the occlusal contacts on a denture (or extensive crown and bridge case). It is
usually defined by the position of the condyles, rather than the teeth. Centric relation can
be thought of as a treatment position, which is not necessarily ideal or normal in the
natural dentition.
“Centric Occlusion” (CO) is usually defined as the maxillomandibular position
determined by the position of the teeth (when present), and is sometimes considered
coincident with maximum intercuspation, habitual closure or other tooth-related position.
The problem with both of these terms (CR and CO) is that they have been defined
differently by various investigators, and differently over different time periods.
Where is CR?
The most recent definition of centric relation in the Glossary of Prosthodontic Terms is:
“The maxillomandibular relationship in which the condyles articulate with the
thinnest avascular portion of their respective disks with the complex in the anteriorsuperior
position against the slopes of the articular eminences. The 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.”