Occlusion Flashcards
Intro to occlusion: Why study occlusion?
Failure of routine restorations
Fractured teeth and restorations
Intro to occlusion: What is ICP?
The position of the mandible when there is maximum intercuspation of the teeth.
Intro to occlusion: What is RCP?
The first tooth contact when the condyles are fully seated in the glenoid fossa
close to RCP then slide into ICP
Intro to occlusion: What is centric relation?
Relation of the mandible to the maxilla when the condyles are seated in the midmost uppermost position in the glenoid fossa - jaw position nothing to do with the teeth
Intro to occlusion: What is the range of movement within centric relation?
25mm - this is hinge movement
Intro to occlusion: What is protrusive excursion?
Starting from ICP the teeth are kept touching each other and the mandible is moved forward slowly
The teeth which are in contact during this movement are said to be in protrusive guidance
Intro to occlusion: What is one of the main factors that determine which teeth are in protrusive guidance?
Incisor classification
Intro to occlusion: Where does protrusive excursion fall in class I incisors?
On the incisors
Intro to occlusion: Where does protrusive excursion fall in class II Div I incisors?
Shallow anterior guidance on the incisors
Initial guidance may be on posteriors
Intro to occlusion: Where does protrusive excursion fall in class II Div II iincisors?
Very steep overbite results in steep guidance on anterior teeth
Intro to occlusion: Where does protrusive excursion fall in class III incisors?
Very little/no/negative overbite results in minimal/no guidance on anterior teeth in protrusion
Posterior teeth will guide in protrusive movements
Intro to occlusion: Where does protrusive guidance fall in an anterior open bite?
No contact between anterior teeth
Posterior teeth will guide in protrusive movements
Intro to occlusion: how do lateral excursions work?
Working side – the side the jaw is moving to
On the working side guidance can be:
Canine guidance
Group Function
Non-working side - the side opposite to which the jaw is moving
Intro to occlusion: Which teeth are in lateral guidance in lateral excursions?
the ones which remain in contact during the jaw moving to either left or right
Intro to occlusion:What is group function?
More than one guiding tooth
Intro to occlusion: What happens to posterior teeth on the non working side during lateral excursions and what can happen if these contact?
Posterior teeth on the non-working side should ideally separate in order to avoid destructive forces on the inclines of the teeth.
Non-working side contacts (also known as interferences) can lead to failed restorations and occlusal disharmony.
Intro to occlusion: What are the steps in undertaking a detailed occlusal analysis?
ICP contacts - Check contacts using Shimstock +/- GHM paper
RCP contacts - manipulate to centric relation, then note first contact with GHM paper
Slide from RCP to ICP - large or small?
Anterior guidance - which teeth guide?
Use Shimstock +/- GHM paper - VERY SLOW MOVEMENT
Posterior disclusion - are there any posterior contacts during protrusive excursion?
Crossover interferences – some people can overlap the upper teeth with the lower incisors
Lateral excursions - which teeth guide? (canine/group)
Use Shimstock +/- GHM to indicate contacts
Ask patient to move jaw very slowly
Any non working side contacts?
Intro to occlusion: When are horse shoe articulating papers used?
Only dentures
Intro to occlusion: When is regular articulating paper used?
OK for most restorations but not for a detailed occlusal analysis
Intro to occlusion: When is GHM paper used?
19 microns thick
Excellent for detailed occlusal analysis
Intro to occlusion: When is Shimstock foil used?
8 microns thick
Excellent for checking contact points
Intro to occlusion: How would you manipulate a patient into centric relation?
Firmly stabilise the head.
Position fingers on lower border of mandible
Thumbs on symphysis. NO pressure yet.
Next WITH A VERY GENTLE TOUCH, manipulate so that jaw hinges slowly open and closed FREELY.
GENTLE but firm guiding of condyles upward with little fingers.
Intro to occlusion: What is the significance of the slide from RCP to ICP?
The slide will show the teeth and cusps which are likely to be under the most load, take care when restoring these teeth
