Centric relation

Centric Relation

Centric relation (CR) is a fundamental concept in dentistry, particularly in the fields of prosthodontics and occlusion. It refers to the maxillomandibular 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 shapes of the articular eminences. This position is independent of tooth contact and is clinically discernible when the mandible is directed superiorly and anteriorly. It is restricted to a purely rotary movement about the transverse horizontal axis.

Definition and Importance

Centric relation is a bone-to-bone relationship, not influenced by the teeth. It is considered a repeatable and reproducible position, which makes it a critical reference point in dentistry for:

• Diagnosing occlusal conditions
• Planning and executing restorative and prosthetic treatments
• Fabricating dental prostheses such as dentures and dental crowns

CR is used as a starting point for developing an optimal occlusion, as it provides a stable and reproducible position for the mandible.

Clinical Application

In clinical practice, centric relation is used to:

• Establish a reference position for mounting dental casts on an articulator
• Diagnose occlusal disharmonies
• Plan comprehensive dental treatments

The determination of centric relation is crucial for the success of full mouth rehabilitation and the construction of complete dentures. It ensures that the occlusal forces are distributed evenly, minimizing the risk of TMJ disorders and other complications.

Methods of Recording Centric Relation

Several techniques are used to record centric relation, including:

• Bimanual manipulation: The dentist uses both hands to guide the mandible into the centric relation position.
• Leaf gauge: A series of thin plastic strips are used to deprogram the muscles and guide the mandible into CR.
• Lucia jig: A device placed on the anterior teeth to separate the posterior teeth and allow the mandible to move freely into CR.

Each method aims to achieve a consistent and repeatable position for accurate diagnosis and treatment planning.

Controversies and Challenges

Despite its importance, centric relation can be challenging to determine accurately. Some controversies include:

• Variability in techniques and practitioner skill
• Differences in patient anatomy and muscle tone
• Debate over the exact definition and clinical relevance of CR

These challenges necessitate a thorough understanding of the concept and careful clinical practice to ensure accurate results.

Also see

• Occlusion (dentistry)
• Prosthodontics
• Temporomandibular joint disorder
• Dental articulator
• Dental prosthesis