Occlusion

Question 1

define occlusion

Answer 1

the static relationship between the incising or masticating surfaces of the maxillary or mandibular teeth or tooth analogues

Question 2

what is the intercuspal position?

Answer 2

the complete intercuspation of the opposing teeth independent of the condylar position
sometimes referred to as the best fit of the teeth regardless of the condylar position

Question 3

name two factors which can change the ICP

Answer 3

• extraction of teeth
  -restorations

Question 4

what is the retruded contact position?

Answer 4

guided occlusal relationship occurring at the most retruded position of the condyles in the joint cavities

Question 5

define index teeth

Answer 5

contacting facets of teeth in the intercuspal position

Question 6

what is the most reproducible position?

Answer 6

the RCP

Question 7

when is the RCP used instead of the ICP?

Answer 7

when there is not enough index teeth and there is an unstable occlusion

Question 8

is it easier to change or conform to the existing occlusion?

Answer 8

conform to

Question 9

when would you conform to the existing occlusion?

Answer 9

• works best in stable occlusion with sufficient index teeth
• usually use ICP
• ensure the prosthesis doesn’t alter the occlusion

Question 10

when would you change the existing occlusion?

Answer 10

• often when the occlusion is unstable and there is a lack of sufficient index teeth
  -usually more challenging to record occlusion
  -often use RCP

Question 11

how do we record occlusion?

Answer 11

using articulated study casts and an interocclusal record

Question 12

give 3 examples of interocclusal records

Answer 12

-bite registration paste
- a wax wafer using modelling wax
- a modified wax wafer e.g. alminax

Question 13

how do we record occlusion when there is a lack of index teeth?

Answer 13

record blocks

Question 14

would the RCP always be used for edentulous patients?

Answer 14

• exam answer yes
• clinic answer no

Question 15

how would you know that the OVD is not being changed at the jaw registration stage for partials?

Answer 15

the index teeth still bite together

Question 16

why is it a good thing if you can see through the wax wafer after recording the occlusion?

Answer 16

thick wax would adjust the OVD

Question 17

name 4 factors influencing the positions and movements of the mandible

Answer 17

-the muscles of mastication
-the neural feedback pathways
-the temporomandibular joints
- the shape of the occluding surfaces of the teeth

Question 18

what is the envelope of motion?

Answer 18

a relatively small space in which the occlusion is achieved during normal functional mandibular movements such as swallowing and chewing

Question 19

what are abnormal movements in the envelope of motion caused by?

Answer 19

derangement of the articular disc and muscle hypertrophy

Question 20

give 4 examples of parafunctional activity

Answer 20

-bruxism
-clenching
-jaw posturing
- lip/pencil biting

Question 21

give 4 consequences of parafunctional activity

Answer 21

-fractured cusps or restorations
-Increased tooth mobility
- muscle fatigue
-tooth wear

Question 22

what is Posselt’s envelope?

Answer 22

represents the movement of the tip of the lower incisor when viewed in sagittal or frontal plane

Question 23

what is the name given to the mandible intitally opening with a hinge movement about a horizontal axis

Answer 23

the retruded Aix/terminal hinge axis

Question 24

what is the most superior position of the condyles in their fossae?

Answer 24

the retruded position

Question 25

is the retruded position clinically reproducible in dentate or edentulous patients?

Answer 25

both

Question 26

how big is the discrepancy between the RCP and ICP?

Answer 26

up to 1mm

Question 27

how big should the freeway space be?

Answer 27

2-4mm

Question 28

what is the occlusal vertical dimension?

Answer 28

measurement of face height when the teeth are in the intercuspal position

Question 29

what determines the path of mandibular teeth moving from ICP to maximum protrusion?

Answer 29

the articulating surfaces of anterior teeth (anterior guidance)

Question 30

what determines the path of mandibular teeth moving from ICP to maximum protrusion in patients with anterior open bites or edge-to-edge incisor relationships?

Answer 30

the occlusal surfaces of posterior teeth

Question 31

what determines the angle and length and movement of teeth from ICP to maximum protrusion

Answer 31

the incisor relationship

Question 32

describe the movement from ICP to maximum protrusion in patients who are class II division 2

Answer 32

the movement is almost vertical as the lower incisors are locked palatal to the upper incisors and cannot slide forward

Question 33

what maintains ICP and directs occlusal forces axially?

Answer 33

- palatal cusps of maxillary teeth - buccal cusps of mandibular teeth (supporting cusps)

Question 34

what do supporting cusps contact?

Answer 34

inclined planes of opposing dentition or cusp tips contact the opposing fossae

Question 35

during lateral excursions, what is the working side and what is the non-working side?

Answer 35

WS- the side to which the mandible moves NWS- the opposite side

Question 36

what is the difference between canine guidance and group function?

Answer 36

CG- during lateral excursion, only the canines on the working side contact GF- during lateral excursion, two or more pairs of teeth contact on the working side

Question 37

describe how the mandible moves from RCP to maximum opening

Answer 37

-rotates around the THA in an arc of a circle to the point Y - the condyles translate/slide downwards and forwards along the articulator eminencies of the glenoid fosse to the point of maximum opening

Question 38

what is the Bennett movement?

Answer 38

condylar movements on the working side in the horizontal plane

Question 39

what is the Bennett angle?

Answer 39

the angle between the non-working side and the sagittal plane during lateral excursion of the mandible

Question 40

how big is the Bennett angle on average?

Answer 40

16o ranges from 2-44

Question 41

how do you locate the RCP?

Answer 41

- pt in supine position with chin pointed upwards - stand behind pt and place thumbs on chin and fingers on lower border of mandible -use gentle manipulation to move the pt into RCP

Question 42

name 4 types of articulator

Answer 42

-simple hinge - average value - semi-adjustable - fully adjustable

Question 43

what movements does a simple hinge articulator allow?

Answer 43

rotational movements only around horizontal axis

Question 44

what movements does an average value articulator allow?

Answer 44

a limited range of protrusive and lateral movements based through a fixed condylar guidance mechanism

Question 45

what are the two types of semi-adjustable articulator?

Answer 45

-arcon -non-arcon