Intro to Clinical Occlusion

Question 1

Why must occlusion be considered in dentistry?

Answer 1

Failure routine restorations
Fractured teeth and restorations
Overeruption and tipping of teeth

Question 2

What are the 3 mandibular positions?

Answer 2

ICP = intercuspal position
RCP = retruded contact position
CR = centric relation

Question 3

What are the mandibular movements?

Answer 3

Lateral excursion
Protrusive excursion

Working and non-working side

Question 4

What is ICP?

Answer 4

Position of mandible when there is maximum intercuspation of the teeth
Stable ICP = locks into position

Question 5

Cause of unstable ICP?

Answer 5

Caused shallow or flat cusps - allow movement and sliding during ICP

Question 6

What is centric relation?

Answer 6

Relation of mandible to maxilla when the condyles are seated in the midmost uppermost position in the glenoid fossa
Allows range of movement (25mm) when condyles are fully seated in glenoid fossa (hinge)

Question 7

What is RCP?

Answer 7

The first tooth contact when the condyles are fully seated in the glenoid fossa (usually molars)

Question 8

Does RCP coincide ICP?

Answer 8

Usually don’t

Close into RCP then slide ICP

Question 9

What is the main factor that determines protrusive guidance?

Answer 9

Incisor classification

Question 10

What is protrusive guidance?

Answer 10

The teeth which are in contact

Question 11

What protrusive guidance would you see with class I incisors?

Answer 11

Usually on incisors - tip lower incisors move on palatal surface
Posterior teeth disocclude and anterior teeth take guidance
Careful bulky restorations palatal surface incisors

Question 12

What protrusive guidance would you see with class II div I incisors?

Answer 12

Shallow anterior guidance - longer path
Deep cusps - posterior teeth may pick up
Initial guidance may be on posterior teeth

Question 13

What protrusive guidance would you see with class II div II incisors?

Answer 13

Steep overbite - steep guidance on anterior teeth

Question 14

What protrusive guidance see with class III incisors?

Answer 14

Very little - no anterior guidance

Posterior teeth will guide in protrusive movement

Question 15

What protrusive guidance will see with AOB?

Answer 15

No contact between anterior teeth

Posterior teeth will guide movement

Question 16

What is lateral excursion?

Answer 16

Starting from ICP jaw moved with teeth kept in contact

The teeth which are in contact during this movement said to be in lateral excursion

Question 17

Difference between working side and non-working side during lateral excursion?

Answer 17

Working side - side jaw moving to

1. Canine guidance
2. Group function

Non-working side - side opposite jaw moving to

1. Posterior teeth should separate to avoid destructive forces
2. Non-working side contacts (inferences) can lead to failed restorations

Question 18

What should be included in occlusal analysis?

Answer 18

1. ICP contacts
2. RCP contacts
3. Slide RCP to ICP
4. Anterior guidance
5. Lateral excursion

Question 19

What equipment should be used for occlusal analysis?

Answer 19

Horeshore articulating paper - thick - used for dentures
Articulating paper - ok for most restarting
GHM paper - good occlusal analysis - dry teeth**
Shimstock foil - good check contact points **

Question 20

How thick is GHM paper?

Answer 20

19 microns

Question 21

How thick is Shimstock foil?

Answer 21

8 microns thick

Question 22

How to find RCP contacts clinically?

Answer 22

Manipulate into CR
Position fingers lower border of mandible and thumbs on symphysis
Manipulate so jaw hinges slowly open and closed
Firm guiding of condyles

Question 23

How to find anterior guidance clinically?

Answer 23

Shimstock/ GHM paper - slow movements

Check posterior disocclusion

Question 24

How to check lateral excursion clinically?

Answer 24

Shimstock/GHM
Which teeth guiding - canines or group function
Check non-working side contacts