Mechanics of mastication/ N22-mastication

Question 1

what is the reason for the breakdown of foodstuffs?

Answer 1

• preparation for swallowing
• increase surface area for chemical digestion
• release of chemicals for sense of taste

Question 2

what is the role of mastication?

Answer 2

• breakdown of foodstuffs
• stimulation of salivary flow
• growth and maintenance of pro-facial tissues

Question 3

what number of teeth is in a functional occlusion?

Answer 3

5-5

Question 4

what is the mechanics of ingestion?

Answer 4

• Stage I transport - food from lips to cheek teeth
• Mastication (chewing)
• Stage II transport - food from cheek teeth to the back of tongue
• swallowing

Question 5

what are the functions of tongue movements?

Answer 5

• directing food
• crushing food
• mixing food and salvia

Question 6

what are the functions of cheek movements?

Answer 6

directing food

Question 7

what are the functions of lip movements?

Answer 7

• accepting food
• retaining food : Anterior oral seal
• directing food

Question 8

Describe the chewing cycle.

Answer 8

a semi automatic process that lasts between 0.5 and 1.2 seconds

Question 9

what are the movements of the condylar head during opening?

Answer 9

Working side head:
-rotates around vertical axis
-moves slightly laterally (Bennett movement)
-very slight posterior movement
Non- working side head:
-moves downwards ,forwards and medially (Bennett angle)

Question 10

what are the movements of the condylar head during closing?

Answer 10

Working side head:
-moves medially to normal position in glenoid fossa (early closing phase)
-rotates back to normal orientation
Non- working side head:
-moves upwards, backwards and laterally
-returns to normal position in glenoid fossa (late in closing phase)

Question 11

what is the sequence of muscle activation

Answer 11

• mylohyoid (Opening)
• digastric (O)
• lateral pterygoid (O)
• temporalis (closing)
• masseter (C)
• medial ptereygoid (C)

Question 12

what muscle is active in both jaw opening and closing?

Answer 12

lateral pterygoid

Question 13

what are the physiological chewing forces?

Answer 13

• 70 to 150N dentate

- Edentulous 4-55N

Question 14

what is the maximum clenching forces?

Answer 14

-500-700N between molars

Question 15

what factors lead towards a preferred side for chewing?

Answer 15

• determined early in life and persists in spite of tooth loss
• whether side is dentate ,partially dentate or edentulous
• restored with a fixed or moveable prothesis
• avoidance of pain/pathology
• occlusal interference

Question 16

what is the masticatory efficiency?

Answer 16

the capacity to reduce the size of food particles by chewing

Question 17

what experimental tests are used to define masticatory efficiency?

Answer 17

• test food and serial sieve
• subjective measures
• measuring maximal biting force
• swallowing threshold test index

Question 18

what factors affect masticatory performance?

Answer 18

• number of teeth in functioning occlusion

- replacement of teeth (fixed or removable prostheses

Question 19

what masticatory performances are less efficient?

Answer 19

F/F due to avoidance and increased number of chewing strokes