occlusion

Question 1

which teeth experience the most force during chewing?

Answer 1

the first molars (first molar region) experience the most occlusal forces during chewing

Question 2

how is the biting force of an individual with complete dentures differ from an individual w natural teeth

Answer 2

chewing and the chewing stroke depend on occlusion. further, an individual eith complete dentures will exert about 1/4 of the chewing forces that an indiv with natural teeth can.will

Question 3

what are the three major functions of the masticatory system?

Answer 3

the three major functions of the masticatory system are 1)mastication, 2) swallowing, and 3) speech

Question 4

T/F tooth contact ocurs during speech

Answer 4

False. Tooth contact does not occur during speech

Question 5

T/F tooth contact occurs during swallowing and is longer than tooth contact of mastication

Answer 5

True. Tooth contact occurs during swallowing (for the purpose of stabilixing the mandbile for somatic swallowing). Cntact of the teeth during swallowing is maintained longer than the tooth cntacts felt in the chewing stroke

Question 6

what portion of the brain controls the chewing stroke?

Answer 6

the central pattern generator of the brainstem controls the chewing stroke.

Question 7

T/F the chewing stroke is cicular

Answer 7

False. the chewing stroke (usually) has a tear-shaped trajectory

Question 8

what are the 2 phases of the chewing stroke

Answer 8

the 2 phases of hte chewing stroke are hte opening and closing meovements of the mandible.

Question 9

what are the 2 phases (list first and second) of the closing pahse

Answer 9

the closing phase is subdivided into the 1) crushing phase and 2) grinding phase

Question 10

what happens if during speech there is tooth contact?

Answer 10

tooth contact does not occur during speech. however, if occlusion is such that tooth contact does occur during speech, the signals are sent to the brain, and the brain forms a new pattern of speech that adjusts and avoids tooth contact.

Question 11

Are the following characterisitics of carnivores, herbivores, or mixed:: (and explain ow the characteristic contributes to the eating mode:

• teeth with high custs
• TMJ restricited mobility
• TMJ at level of tooth row
• emphasis on temporalis muscle
• zygotmatic arch narrow

Answer 11

the listed items are characterisitics of CARNIVORES

• teeth with high custs
• TMJ restricited mobility= high force generation
• TMJ at level of tooth row=promotes force generation, ripping, and grapping
• emphasis on temporalis muscle =temporalis has a bigger role than the other masticatory mm
• zygotmatic arch narrow= due to deemphasis on the masseter muscle

Question 12

the following are characteristics of: carnivors, herbiviores, or mixed?

• flat teeth, low cusps
• TMJ is highly mobile
• TMJ is above the tooth row
• emphasis on the masseter/medial pterygoid
• zygomatic arch is wide

Answer 12

the listed characteristics = flat teeth/low cusps, mobile TMJ, TMJ above hte tooth row, empahsis on the masseter and medial pterygoid mm, andd wide aygomatic arch are all characteristics of an HERBIVORE

Question 13

based on the shape of the jaw, the resultant force vector may or may not indicate force on the TMJ,. when the bite force is vector through the bite point (occlusion) then the TMJ receives less load

Answer 13

True. if the jaw is shaped such that the bite force (as displayed by a vector) goes through the bite point (occlusion) then the TMJ receives less load than if the bite force did not travel through the bite plane.

Question 14

Does the human TMJ receive load during mastication?

Answer 14

Whether or not hte human TMJ is under load during mastication is still a topic of controversy,. some studies demonstrate yes it is, and other studies demostrate that it is not under load..

Question 15

How is the cross-sectional area of a muscle related to force generated?

Answer 15

The force generated by a muscle is directly proportional to the cross-sectional area of all of hte muscle fibers – so large muscles can gernate more force and power than small muscles

Question 16

T/F - a short muscle can shorten about 80% of its length at rest and therefore generate more force than a long muscle

Answer 16

False. All muscles shorten to apprx 50% of their resting length. This has implication on range of memvent (vs force) where a long muscle has a larger range of motion vs a short muscle

Question 17

T/F pinnate muscles are able to generate a lot of force without large muscles that bulge up. The sartoirius is an example

Answer 17

T and F.
pinnate muscles are able to generate a lot of foce without large muscles that bulge up. However, the sartorius is not a pinnate muslce (it is a strap muscle– with long fibers for range of motion). The deltoid muscle is an example of a pinnate arrangement

Question 18

name the five muscles that originate from the calvaria and insert into th mandible

Answer 18

the five muscles that origniate in the calvaria (skull cap) and insert into the mandible are the

• masseter
• temporalis
• medial pterygoid
• lateral pterygoid
• digastric m.

Question 19

which muscles that span the calvaria to the mandible are multipinnate - and why?

Answer 19

the muslces that span from the skull cap to the mandible are the temporalis, the masseter, and the medial pterygoid.
-pinnate muscles are able to generate a lot of force, in the jaw, the range of motion is limited (by occlusion) so the pinnate mm are able to generate high force without a lot of movement

Question 20

T/F the TMJ works as a first, second, and thrid class of lever system (depenidng on the action, etc)

Answer 20

True. The TMJ can act as a first class lever system, second class, or thrid class lever system depednng on its action.

Question 21

which class of lever system is the most efficient? (most amount of work for least amount effort).
when is the TMJ this sort of lever?

Answer 21

The first class lever system is the most efficient sort. The TMJ is a first class lever when at rest (first class:: force located posterior, fulcrum cnetral, and weight anterior)

Question 22

when is the TMJ a second calss lever - and what is a 2nd class lever?

Answer 22

The TMJ is a second class lever system during mastication. The weight of the system is positioned bt the force and the fulcrum 9FORCE APPLIED ON THE CHEWING SIDE, FULCRUM IS the nonworking side, opposite locaiton of hte food, and the weight is inbetween the force and fulcrum)

Question 23

what are the three types of muscle movemvents?

Answer 23

there are three types of muscle movements:

• opening-closing
• protrusion-retrusion
• lateral shifts

Question 24

which muscles are reposnible for the openin of the jaw?

Answer 24

the digastric muscle and the inferior head of hte inferior pterygoid are responsible for the opeing of the jaw ** notice, opening the jaw is a SYMMetrical movement

Question 25

which muslces are responsible for hte closing of hte jaw?

Answer 25

the masseter, medial pterygoid, teporalis, and superior head of the lateral pterygoid are responsible for hte closing of the jaw **notice, the closing of hte jaw is a SYMM movement

Question 26

which muslces are responsbile for the lateral shifting of the jaw/

Answer 26

thelateral pterygoid is on the balancing side (the side the jaw shfits away from), and the temporalis moves the working side *the side to which you shift jaw towards) ** notice, this is an asymmetrical jaw movement

Question 27

which muscles are responsbile for the protrusion/retrusion motions of hte jaw?

Answer 27

the lateral pterygoid and the posterior temporalis are responsible for the protrusion.retrusion actions of the jaw **notivce, the prtrusion;.retursion of the jaw is a SYMMmetrical movement

Question 28

what is the purpose of an incisal guidance table?

Answer 28

the creation of an icisal guidance table has 2 uses: 1) to record tjhe existing guidance (characterisitics of the specific jaws movements acording to canine and incidal parameters - aka guidance)
2) to protect the wax patterns made (that will rebuild the occlusion- the incisal guide makes sure that the articulator does not close in a way that destroys the wax build-up)

Question 29

canine guidance establishes what direction of movement?

Answer 29

canine guidance establishes the parameters of lateral movement

Question 30

what movements are recorded in an incisal guide table memry resin>

Answer 30

the incisal guide table is created by recording hte movements (pathway) made by protrusive, lateral, lateral protrusive intermediate motions (via canine cusp to canine cusp, and guiding the MAX incisors over the MAND incisors in protrusion/retursion)