5 - Occlusion 1

Question 1

What are the different movements of the mandible?

Answer 1

• rotation
• translation
• lateral translation

Question 2

Describe rotation of the mandible.

Answer 2

• small opening of mouth up to 2cm
• condyle and disc remain in articular fossa
• no downwards or forwards movement
• hinge action

Question 3

What is a face bow?

Answer 3

Used to record the terminal hinge axis and the distance between the condyles

Question 4

Describe translation of the mandible.

Answer 4

• wider opening of the mouth
• lateral pterygoids contract
• articular disc and condyle move forwards and downwards towards the articular eminence

Question 5

What is Posselts envelope?

Answer 5

• extremes of mandibular movement
• border movements of the mandible in the sagittal plane

Question 6

What are the points of Posselts envelope?

Answer 6

• ICP
• edge to edge (E)
• protrusion (Pr)
• Maximum opening (T)
• retruded axis position (R)
• RCP

Question 7

What is ICP?

Answer 7

• tooth position regardless of condylar position
• comfortable bite and best fit of teeth
• maximum interdigitation
• aka centric occlusion

Question 8

What is E?

Answer 8

• edge to edge
• tooth position
• teeth slide forward from ICP on the palatal surfaces of the anterior teeth
• upper and lower incisal edges contacting

Question 9

What is Pr?

Answer 9

• protrusion
• jaw position
• condyle moves forwards and downwards on articular eminence
• no posterior tooth contacts, eventually no anterior either

Question 10

What is T?

Answer 10

• maximum opening
• jaw position
• mouth wide open, no tooth contacts
• full translation of condyle over articular eminence

Question 11

What is R?

Answer 11

• retruded axis position
• jaw position
• no tooth contacts
• most superior anterior position of the condylar head in fossa
• terminal hinge axis

Question 12

What is RCP?

Answer 12

• retruded contact position
• first tooth contacts when mandible is in retruded axis position
• RCP is approx 1mm posterior to ICP

Question 13

What is lateral translation?

Answer 13

• known as Bennet movement
• contraction of one lateral ptyegoid (working side) causes bodily shift of mandible to that side

Question 14

What is the Bennet angle?

Answer 14

Angle created by the path of the nonworking condyle in the horizontal plane during lateral excursion

Question 15

What is a mutually protected occlusion?

Answer 15

Canine guidance with molar disclusion