Occlusion

Question 1

Intro to occlusion: Why study occlusion?

Answer 1

Failure of routine restorations

Fractured teeth and restorations

Question 2

Intro to occlusion: What is ICP?

Answer 2

The position of the mandible when there is maximum intercuspation of the teeth.

Question 3

Intro to occlusion: What is RCP?

Answer 3

The first tooth contact when the condyles are fully seated in the glenoid fossa

close to RCP then slide into ICP

Question 4

Intro to occlusion: What is centric relation?

Answer 4

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

Question 5

Intro to occlusion: What is the range of movement within centric relation?

Answer 5

25mm - this is hinge movement

Question 6

Intro to occlusion: What is protrusive excursion?

Answer 6

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

Question 7

Intro to occlusion: What is one of the main factors that determine which teeth are in protrusive guidance?

Answer 7

Incisor classification

Question 8

Intro to occlusion: Where does protrusive excursion fall in class I incisors?

Answer 8

On the incisors

Question 9

Intro to occlusion: Where does protrusive excursion fall in class II Div I incisors?

Answer 9

Shallow anterior guidance on the incisors

Initial guidance may be on posteriors

Question 10

Intro to occlusion: Where does protrusive excursion fall in class II Div II iincisors?

Answer 10

Very steep overbite results in steep guidance on anterior teeth

Question 11

Intro to occlusion: Where does protrusive excursion fall in class III incisors?

Answer 11

Very little/no/negative overbite results in minimal/no guidance on anterior teeth in protrusion
Posterior teeth will guide in protrusive movements

Question 12

Intro to occlusion: Where does protrusive guidance fall in an anterior open bite?

Answer 12

No contact between anterior teeth

Posterior teeth will guide in protrusive movements

Question 13

Intro to occlusion: how do lateral excursions work?

Answer 13

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

Question 14

Intro to occlusion: Which teeth are in lateral guidance in lateral excursions?

Answer 14

the ones which remain in contact during the jaw moving to either left or right

Question 15

Intro to occlusion:What is group function?

Answer 15

More than one guiding tooth

Question 16

Intro to occlusion: What happens to posterior teeth on the non working side during lateral excursions and what can happen if these contact?

Answer 16

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.

Question 17

Intro to occlusion: What are the steps in undertaking a detailed occlusal analysis?

Answer 17

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?

Question 18

Intro to occlusion: When are horse shoe articulating papers used?

Answer 18

Only dentures

Question 19

Intro to occlusion: When is regular articulating paper used?

Answer 19

OK for most restorations but not for a detailed occlusal analysis

Question 20

Intro to occlusion: When is GHM paper used?

Answer 20

19 microns thick

Excellent for detailed occlusal analysis

Question 21

Intro to occlusion: When is Shimstock foil used?

Answer 21

8 microns thick

Excellent for checking contact points

Question 22

Intro to occlusion: How would you manipulate a patient into centric relation?

Answer 22

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.

Question 23

Intro to occlusion: What is the significance of the slide from RCP to ICP?

Answer 23

The slide will show the teeth and cusps which are likely to be under the most load, take care when restoring these teeth