Intro Flashcards
Why study occlusion?
Failure of routine restorations
-e.g. fractures
-fractured teeth and restorations could be due to bruxism
Over eruptions and tilting (of UR6 and UR7)
Large under contoured amalgam (on LR6)
ICP
The position of the mandible when there is maximum intercuspation of the teeth
RCP
First point of contact in the centric relation arch
First tooth that meets when condyles are fully seated in glenoid fossa
Centric relations
Relation of the mandible to the maxilla when the condyles are seated in midmost uppermost position in the glenoid fossa
Jaw position, nothing to do with teeth
20-25mm of pure rotation when the condyles are fully seated in the glenoid fossa
A hinge movement
Lateral excursions
Side to side
Working side (side the jaw is moving to)
-guidance can be canine guidance or group function
Non-working side (the side opposite to which jaw is moving)
Protrusive excursions
Starting from ICP teeth are kept touching each other and mandible moved forward slowly
Teeth in contact during this movement said to be in protrusive guidance
One of main factors which determines which teeth are in protrusive guidance is the incisor classification
Working and non-working side
Working side: the side the jaw is moving to
-guidance can be canine guidance/ group function
Non-working side - the side opposite **
RCP vs ICP
Usually do not coincide
We can close to RCP then SLIDE to ICP
RCP vs ICP
Usually do not coincide
We can close to RCP then SLIDE to ICP
Protusive guidance - class II division 1
Shallow anterior guidance
Initial guidance may be on posteriors
Protusive guidance - class II division 2
Very steep overbite results in steep guidance on anterior teeth
Protrusive guidance - class III
Very little/ no/ negative overbite results in minimal/ no guidance on anterior teeth in protrusion
Posterior teeth will guide in protrusive movements
Protrusive guidance - class I
Protrusive excursion usually on the incisors
Protrusive guidance - anterior open bite
No contact between anterior teeth
Posterior teeth will guide in protrusive movements
Non working side
Posterior teeth on non-working side should ideally separate in order to avoid destructive forces on inclines of teeth
Non-working side contacts (also known as interferences) can lead to failed restorations and occlusal disharmony
Centric relation manipulation
Dorsum hold? **
- ICP contacts
Check contacts using shimstock +/- GHM paper (finer paper with finer ink)
Dry tooth
Tap tap tap
AND/ OR shimstock paper, try to pull it out and if it doesn’t it’s in ICP
GHM paper
19 microns thick
Excellent for detailed occlusal analysis
Shimstock foil
8 microns thick
Excellent for checking contact points
- Anterior guidance
Which teeth guide?
Use Shimstock +/- GHM paper - very slow movement
Posterior disclusion - are there any posterior contacts during protusive excursion?
Crossover interferences - some people can overlap the upper teeth with lower incisors
- Lateral excursions
Visually +/- GHM (Shimstock not as good)
Which teeth guide the excursion? (canine guidance or group function)
Ask px to move jaw very slowly
Any non-working side contacts?
Routine restorations
Look at starting point
- Which teeth contact in ICP, RCP and is tooth involved in guidance?
- Complete restoration
- Now check ICP and RCP contacts again, and protrusive / lateral excursions
Horseshoe articulating paper
Too thick
Only to be used for dentures
Regular articulating paper
OK for most restorations but not for detailed occlusal analysis