Dental Occlusion Concepts

Centric Relation

• Independent of tooth contact.
• Condyles articulate in the anterior-superior position against the posterior slopes of the articular eminences.
• The patient can make vertical, lateral or protrusive movements from this position.
• Clinically useful, repeatable reference position.

Centric Occlusion

• Maximum planned contact or intercuspation of opposing occlusal surfaces.
• It is a term used to denote any contact of the denture teeth other than centric occlusion.

Eccentric Occlusion

• Any contact of the denture teeth other than centric occlusion.

Differences Between Natural and Complete Artificial Occlusion

• Natural Dentition:
  • Teeth are attached to bone by periodontal ligaments.
  • Teeth receive individual pressure of occlusion and can move independently to adjust.
  • Horizontal (lateral) forces exerted on natural teeth during mastication affect only the teeth involved.
  • Occlusion in centric relation can initiate interferences and responses that direct the mandible into centric occlusion.
• Complete Artificial Dentition:
  • Bilateral balance is considered necessary for denture base stability.
  • Incising with artificial teeth affects all the teeth on the base.
  • Proprioceptors impulses created by closure into centric occlusion establish a memory pattern that permits the mandible to return to this centric occlusion position away from centric relation.

Axioms of Artificial Occlusion

• The wider and larger the ridge, the narrower the teeth and closer the teeth are to the ridge, the greater the lever balance.
• The more centered the force of occlusion anterior-posteriorly, the greater the stability of the base construction.

Types of Occlusion

• Bilateral Balanced Occlusion: Maximum contact in working and non-working sides.
• Unilateral Balanced Occlusion (Group Function): Maximum contact in working side and no contact in non-working side.
• Mutually Protected Occlusion:
  • Also known as canine protected occlusion, or organic occlusion.
  • Maximum contact at centric occlusion.
  • No posterior contact during protrusion.
  • The anterior teeth prevent the posterior teeth from contacting on either the working or the non-working sides during mandibular excursions.

Denture Occlusion

• Bilateral Balanced Occlusion in Natural Dentition:
  • Sliding movement of the mandible as it moves from retruded contact position to intercuspal position (a combination of forward and lateral movements, as well as vertical components).
  • Subject natural teeth on the balancing side to destructive obliquely directed forces.
• **Unilateral Balanced Occlusion (Group Function) **
  • Two or more teeth, other than canines, in contact on the working side and no balancing contacts.
• **Mutually Protected Occlusion **
  • Overlap of anterior teeth prevents posterior teeth from making any contact during mandibular excursions.
  • Posterior teeth are separated from contact during mandibular excursions.
  • This separation is termed disclusion.