Y2 L2 Introduction to articulators and occlusion Flashcards
What is occlusion?
- The relationship of the teeth to each other
- Movement of the mandible relative to the skull
- Movement of teeth against each other
- Relationship and movement of teeth (natural or prosthetic) to each other
Name the 4 mandibular movements.
- Retraction
- Protraction
- Elevation
- Depression
What muscles are involved in retraction of the mandbile?
- Horizontal fibres of temporalis
- Deep layers of masseter
What muscle is involved in protraction of the mandbile?
Lateral pterygoid
What muscles are involved in elevation of the mandbile?
- Superficial and medical layers of masseter
- Medial pterygoid
- Vertical fibres of temporalis
What muscles are involved in depression of the mandbile?
- Digastric
- Geniohyoid
- Mylohyoid
- Platysma
What are the muscles of mastication?
- Temporalis
- Masseter
- Lateral pterygoid
- Medial pterygoid
What is Posslet’s envelope of movement?
Refers to the range of movement of the mandible in 3 dimensional space.
Define centric occlusion.
The occlusion of the opposing teeth when the mandible is in centric relation.
Define centric relation.
Where the condyles are in the most anterior superior position in the glenoid fossae.
Jaw to jaw relation, not tooth related.
With complete dentures and partial dentures with no tooth-tooth contacts, we aim for CR=CO.
Define retruded contact position.
When the condyles are in the most posterior position in the glenoid fossae.
Define maximum intercuspal position.
Complete intercuspation of opposing teeth.
ICP coincides with CR in about 10% of the population.
Why are articulators used?
- Stimulate jaw movement
- Diagnose dental occlusal conditions
- To plan dental procedures e.g. crowns, bridges, dentures and aid in their fabrication
Name 3 articulator types.
- Simple hinge
- Free plane/average value
- Semi-adjustable (arcon/non-arcon)
Describe the simple hinge articulator.
- Most simple type
- Casts attached to prongs
- Produces simple opening and closing movements, no lateral, forward, backward etc.
Describe the free plane/average value articulator.
- Simulates the TMJ
- Set at an average value
- Vertical movements (open and close) and lateral movements
Describe the semi-adjustable (arcon/non arcon) articulator.
- More freedom of movement
- Requires a facebow to have the casts mounted
- Arcon and non arcon types are dependent on whether or not the articulator reproduces natural anatomy in a correct or incorrect way (arcon = correct)
- Ultimately, both produce the correct occlusion just in different ways
Describe how semi-adjustable articulator casts are mounted.
