M+O 6 - dynamic occlusion

Question 1

What is occlusion?

Answer 1

the contact relationship of teeth or equivalent

Question 2

What is articulation?

Answer 2

the dynamic relationships of the teeth when in sliding contact

Question 3

What is jaw relationship?

Answer 3

positional relationship which the mandible bears to the maxilla

Question 4

What are the 3 vertical jaw relationships?

Answer 4

• rest/postural position
• intercuspal positon (ICP)
• retruded contact position (RCP)

Question 5

What are the 3 vertical jaw dimensions?

Answer 5

• occlusal vertical dimension (OVD)
• rest vertical dimension (RVD)
• freeway space (FWS)

Question 6

If you have done a filling on a patient, what should you check?

Answer 6

check bite to check the ICP

Question 7

What is the rest/postural position?

Answer 7

at rest - teeth apart

Question 8

How is the rest/postural position maintained?

Answer 8

• minimal muscle activity or…
• is it governed by muscle elasticity

Question 9

Is rest/postural position reproducible?

Answer 9

remains reproducible throughout life in both dentate and edentulous subjects

Question 10

When in rest/postural position of particular clinical importance?

Answer 10

when making full dentures

Question 11

What is ICP?

Answer 11

• maximal intercuspation/interdigitation
• depends on dentition
• ICP changes, rest position doesn’t

Question 12

What is the jaw in RCP (or ligamentous position)?

Answer 12

• condyles retruded in the glenoid fossa
• teeth in contact
  
  • ~1-2mm posterior to ICP
  • same as ICP in 10-20% of patients

Question 13

What is the clinical significance of RCP?

Answer 13

• symmetrical retrusion
• gives a reproducible relationship between the maxilla and mandible

Question 14

What is the OVD?

Answer 14

• the face height with the teeth in ICP
• measured between 2 arbitrary points
• governed by the height of the teeth

Question 15

What can be used to measure OVD?

Answer 15

Willis gauge
- measures from under nose to under chin

Question 16

What is RVD?

Answer 16

• face height with mandible in rest/postural position
• measured between 2 arbitrary point
• this should not alter significantly throughout life

Question 17

What is FWS?

Answer 17

• the space between teeth in rest position
• difference between RVD and OVD
• 2-5mm

Question 18

How do you calculate FWS?

Answer 18

RVD-OVD=FWS

Question 19

What is it called with the FWS is too big and the OVD is too small?

Answer 19

overclosure

Question 20

What are the 5 border movements of the mandible?

Answer 20

• ICP
• RCP
• lower extent of retruded hinge arc
• maximum opening
• maximum protrusion

Question 21

What are the 3 anatomical guide planes?

Answer 21

• incisal guidance
• cuspal inclines
• TMJ

Question 22

What is the ‘working side’?

Answer 22

• the side to which the teeth move
• teeth contact by guidance:
  
  • canine guidance
  • group function

Question 23

What is the ‘non-working side’?

Answer 23

• the side away from which the teeth move
• teeth do not contact - disclude
  -occasional contact can occur e.g. X-bite, after extractions, URAs

Question 24

Why do the teeth on the non-working side not contact?

Answer 24

because the condyle drops down

Question 25

What is canine guidance, and what is group function?

Answer 25

• canine guidance - canines in contact
• group function - multiple teeth in contact

Question 26

What happens to the condyle on the working side?

Answer 26

• rotates around vertical axis
• lateral bodily movement - Bennet movement

Question 27

What happens to the condyle on the non-working side?

Answer 27

• moves downwards
• forwards over eminence
• moves medially

Question 28

What muscle pulls the condyle on the non-working side forward?

Answer 28

lateral pterygoid

Question 29

What is the balanced occlusion concept?

Answer 29

• tooth contact during excursion at both working and non-working sides
• difficult to achieve because teeth rarely in contact
• cannot exist in a normal dentate occlusion

Question 30

Why is the balanced occlusion concept ideal for F/F dentures?

Answer 30

• maintains stability
• control cusp shape/tooth position and orientation