occlusion

Question 1

3 parts that make up the articulatory/masticatory system

Answer 1

temporomandibular joints, occlusion, muscles of mastication

Question 2

What are the 3 parts of a cusp?

Answer 2

ridge, cusp tip, slope

Question 3

Where does the word ‘occlusion’ come from?

Answer 3

occludere is Latin for ‘to close up’

Question 4

What is the static occlusion?

Answer 4

The occlusion the patient makes when they fit teeth together

Question 5

How would you ask the patient to show their static occlusion?

Answer 5

swallow and keep teeth together

Question 6

Other terms for static occlusion

Answer 6

centric occlusion (CO), habitual bite, maximum intercuspation (MIP), intercuspal position (ICP)

Question 7

What is dynamic occlusion?

Answer 7

the sideways movement of the mandible from a centric position

Question 8

Other terms for dynamic occlusion

Answer 8

mandibular eccentric movements, lateral excursion

Question 9

How can occlusal contacts be marked?

Answer 9

articulating paper

Question 10

How is articulating paper held in the patient’s mouth?

Answer 10

Miller forceps (securely and smoothly grip entire length of paper)

Question 11

Why are 2 colours of articulating paper used?

Answer 11

To identify occlusal contacts in static and dynamic occlusion

Question 12

Alternative methods of holding articulating paper that Miller forceps?

Answer 12

Y-type articulating paper holder, fix-clip bite frame (autoclavable)

Question 13

Disposable equipment that can be used to mark occlusal contacts without needing forceps

Answer 13

bite-check articulating film from microscopy

Question 14

How can contact artefacts be created?

Answer 14

when thick articulating paper is used (200u) or when teeth are wet

Question 15

Why should thin articulating paper be used?

Answer 15

minimise contact artefacts and clearly indicate only the small points of true contact

Question 16

How thin should articulating paper be?

Answer 16

40u

Question 17

When is it acceptable to use thick articulating paper (200u)?

Answer 17

for dentures

Question 18

How can teeth be dried before using articulating paper?

Answer 18

using 3-in-1, cotton rolls (must be removed to avoid risk of inhalation)

Question 19

What can broad and rubbing ICP contacts be associated with?

Answer 19

Occlusal problems such as tooth wear, attrition. (first must exclude it is an artefact)

Question 20

Appearance of heavy/high contacts with articulating paper

Answer 20

more colour is squeezed out (greatest masticatory pressure)

Question 21

Term used to describe non-carious lesions that result from attrition

Answer 21

wear facets

Question 22

Why do heavy contacts (premature contacts) need to be resolved?

Answer 22

Could lead to a fracture, or sensitivity

Question 23

Which are the supporting cusps to occlusal stability?

Answer 23

Mandibular buccal cusps and maxillary palatal cusps

Question 24

Which are the non-supporting cusps?

Answer 24

Mandibular lingual cusps and maxillary buccal cusps

Question 25

What is stable occlusion?

Answer 25

Cusp tips lie in opposing fossa / marginal ridge or tripodization around the fossa

Question 26

What is tripodization?

Answer 26

3 reciprocal incline contacts (3 points around fossa) which is even better for stabilisation

Question 27

Which areas of the tooth should occlusal contacts be avoided?

Answer 27

On restored surface and on the border between enamel and restoration

Question 28

Name of a digital tool used to analyse occlusal forces in place of articulating paper

Answer 28

T scan

Question 29

Advantage of T scan

Answer 29

shows how much pressure is exerted in each point of contact (red=heavier contact)

Question 30

Disadvantage of T scan

Answer 30

expensive and 60u thick (not as thin as 40u articulating paper)

Question 31

What is an infra-occluded restoration?

Answer 31

When the tooth has been grinded down to avoid occluding with opposing tooth

Question 32

What is the harm with infra-occluded restorations?

Answer 32

the tooth will over erupt to create an unstable occlusion

Question 33

Function of Shimstock foil

Answer 33

a metal foil used to check firmness of occlusal contacts in comparison to how it was before the restoration (e.g. on index teeth - moulds)

Question 34

Thickness of Shimstock foil

Answer 34

8 microns (u)

Question 35

How can shimstock foil be used to check a restoration?

Answer 35

Shimstock should be firmly held in place in ICP by both the restoration and adjacent teeth. Shimstock should hold the same with and without the restoration.

Question 36

What are the shimstock contacts like for anterior teeth?

Answer 36

light contacts - should be kept after restoration

Question 37

What would you ask the patient to do to check their dynamic occlusion?

Answer 37

Slide their jaw from side to side

Question 38

Which teeth guide the mandible during lateral excursions of the jaw?

Answer 38

lower canines

Question 39

What happens in terms of occlusion during dynamic occlusion?

Answer 39

upper and lower canines are in contact which results in posterior teeth disocclusion.

Question 40

Term used to describe multiple contact relations between maxillary and mandibular teeth (inc canines) in lateral movements

Answer 40

group function

Question 41

Down to how thin can materials be for the periodontal ligament to detect?

Answer 41

half the thickness of human hair

Question 42

What is the conformative approach?

Answer 42

restoring the occlusion in harmony with the existing ICP (mark occlusal contacts before and after)

Question 43

During lateral mandibular movement, which condyle is the working side?

Answer 43

The side the mandible moves towards is the working side.

Question 44

Name of the angle formed between the sagittal plane and the path of the mandibular condyle during lateral movement

Answer 44

Bennett angle

Question 45

In which condyle is the Bennett angle formed?

Answer 45

non-working side

Question 46

How is Shimstock used by the dentist and technician to check the articulator has the same bite as the patient?

Answer 46

To ensure each pairs of teeth (e.g. 17 and 47) have the correct occlusion. Shimstock will hold/pull through for the same pairs of teeth.