Ideal occlusion Flashcards
Gnathological occlusion
Highly engineered
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What is the definition of ideal occlusion (2)
Distribution of load in most favourable way
Workable occlusal scheme
Simple to apply these principles in practice
Principles of ideal occlusion (4)
RCP = ICP
Forces directed through the long axis of the teeth
Posterior disclusion in eccentric positions
Mutual protection
What does RCP = ICP mean for anterior and posterior teeth and why? (4)
Posterior teeth contact
Anterior teeth have light contact only
Occlusal load directed through long axis of teeth
Condyles also ‘positioned’ to distribute load into bone with minimal muscular involvement
People who’s RCP ≠ ICP (3)
Functioning in ICP requires muscular activity to position the condyle and intra articular disc.
80-90% of population have RCP ≠ ICP.
Most people function perfectly well
Why should forces be through long axis of teeth (4)
Distributes occlusal loads favourably Contacts on inclines results in horizontal forces -wear -tooth movement -bone loss -fracture of restorations
What is posterior disclusion and why is it important? (3)
The anterior teeth disclude the posterior teeth
Avoids lateral forces on posterior teeth
Simple to engineer
-often only one tooth contact in eccentric positions
-three contacts between mandible and skull
If posterior contacts do occur
- on working side
- on non-working side
- in protrusion
WS: group function
NWS: interference (undesirable)
Protrusion: interference (undesirable)
What dictates movement in anterior guidance? Where would an interference occur?
Palatal surfaces of upper anterior teeth
An interference would occur on mesial of lower and distal of upper teeth
Mutual protection in ICP and excursions (2)
ICP: posterior protect anterior teeth
Excursions: anterior protect posterior teeth
Why is canine guidance good? (4)
Because of the morphology of the canine
- crown:root
- distant from hinge
- distant from muscle
- highly innervated
Class I definition
Lower incisor occludes at or below the upper incisor cingulum plateau
Class II div I definition
Lower incisor occludes behind the upper incisor cingulum plateau
Class II div 2 definition
Lower incisor occludes behind the upper incisor cingulum plateau
Upper central incisors are retroclined
Class III definition
Lower incisors occludes in front of the upper incisor cingulum plaeau
AOB definition
No contact on anterior teeth
What does the ideal occlusion mean in practice? (5)
Look at existing occlusion: know the tooth contacts
Conforming: Don’t introduce unfavourable contacts
Reorganising: Work to the ideal Occlusion
Know RCP and ICP contacts preoperatively
Know RCP and ICP contacts postoperatively
Movement of the mandible is dictated by
The position of the condyle in the fossae
Condylar pathway along the articular eminence
Teeth ‘interfere’ with this border movement
What is the only position where the mandible can rotate about a hinge without using the lateral pterygoid muscles to brace the closing muscles
Centric relation
Positive aspects of centric relation
The neuromuscular system can function optimally
It is repeatable
When would you use centric relation? (5)
Complete dentures Routine restorations to check RCP Re-organising occlusion to create new ICP coincident with RCP For mounting models for analysis in CR Making hard splints
Deprogramming neuromuscular system into CR depends on (4)
Operator ability
Tooth mobility
Edentulous areas
Difficulty of patient
Methods for deprogramming neuromuscular system into CR (5)
Bilateral manual manipulation (Dawson technique) Cotton wool rools Anterior jigs (Lucia) Gothic Arch Tracing Flat plane splint
Methods for recording centric relation (3)
Manual manipulation into wax or silicone
Anterior jug with silicone
GAT with silicone
Verifying centric relation records (3)
Compare 2 or more records.
Difficult because they may be recorded at different OVD anywhere within CR
Vericheck/Centricheck
