Intro to masticatory systems

Question 1

Functional disturbances of masticatory system include:

Answer 1

• swallowing habits (ex. tongue thrusting)
• chewing patterns
• Bruxism (clenching and grinding)

Question 2

Causes of open bite

Answer 2

1. faulty postural performance of the associated musculature
2. digit sucking habits
3. tongue thrusting
4. Obstructed Nasorespiratory function
5. unfavorable growth patterns
6. imbalances between occlusal and eruptive forces

Question 3

Condyle inclination throughout the lifetime

Answer 3

As patient ages, the condylar inclanation increases to about 20-30 degrees. As children, it is FLAT and thus easier to move around. At old age, condyle is flat once again

Question 4

____ is static, while ___ is dynamic

Answer 4

OCCLUSION is static, hie articulation is DYNAMIC

Question 5

Define occlusion

Answer 5

static.

relationship between Mx and Md teeth in contact

Question 6

Define articulation

Answer 6

• dynamic

- relationship of teeth to their antagonists during mandibular movements (eg. mastication)

Question 7

Each primary tooth occludes with 2 teeth in the opposite arch, except for:

Answer 7

Primary Mc central incisors

Primary Mx 2nd molars

Question 8

The relationship of the 2nd primary mx molar to 2nd primary md molar indicates what?

Answer 8

future positioning of permanent molars.
Flush - (distal of mx and md 2nd molars line up in a straight line) indicates development of class I molar relationship in permanent dentition
Distal step - (distal border of mx 2nd molar is mesial to the distal border of the md 2nd molar) indicates dev. of class II
Mesial step - (distal border of mx 2nd molar is distal to md 2nd molar) indicates class III

Question 9

Why is spacing in permanent dentition important?

Answer 9

in order to accommodate the permanent dentition

Question 10

Primate space:

Answer 10

-exists in Mx and Md anterior segment
-Md: distal to primary canines
Ms: mesial to primary canines

Question 11

Leeway space:

Answer 11

Space difference between total mesiodistal width of primary molars and total mesiodistal width of permanent premolars
-sum of M-D premolars < sum of M-D primary molars

Question 12

molar class I occlusion

Answer 12

-Describes posterior segment

MB cusp of Mx 1st M interdigitates with B groove of Md 1st M

Question 13

canine class I

Answer 13

• describes anterior segment

- cusp of Mx canine interdigitates between Md canine and Md 1st PM

Question 14

Class II malocclusion

Answer 14

Md arch is DISTAL to idea position of the Mx arch by at least 1/2 cusp
Div 1: proclined Mx laterals
Div 2: retroclined Mx laterals

Question 15

Class III

Answer 15

Md arch is MESIAL to the ideal position of Mx arch by at least 1/2 a cusp
-Associated with anterior and/or posterior crossbite

Question 16

Anterior crossbite

Answer 16

“underbite”

-Mx anteror teeth occlude lingual to mandibular anterior teeth

Question 17

Posterior crossbite

Answer 17

Buccal cusp tips of Mx posterior contact Md posterior teeth

-transverse discrepancy between Mx arch width and Md arch width

Question 18

Goals of good occlusion

Answer 18

• optimal function

- absence of disease

Question 19

Ideal dental arch form

Answer 19

U shaped

Question 20

Ideal incisal relationship

Answer 20

correct overjet: about 2mm

Correct overbite: 20-30% of cervicoincisal length of Md incisor

Question 21

Teeth should follow curve of _____ anterioposteriorly, and curve of ____ mediolaterally

Answer 21

Teeth should follow curve of SPEE anterioposteriorly, and curve of WILSON mediolaterally

Question 22

3 arch form shapes

Answer 22

square, tapered (towards anterior), ovoid

Question 23

Overjet vs overbite

Answer 23

Overjet: horizontal overlap.
Overbite: vertical overlap

Question 24

Negative percentage of overbite indicates

Answer 24

an open bite

Question 25

overbite value of or close to 100% is called

Answer 25

deep (impinging) bite

Question 26

Causes for deep bite maloclussions

Answer 26

1. overeruption of the Mx incisor
2. incisor angulation
3. excessive overjet
4. undereruption of the molars
5. Md ramus height
6. Failure of natural eruption

Question 27

prolonged thumb sucking can lead to

Answer 27

anterior open bite due to negative pressure created within the mouth

Question 28

In an ideal occlusal scheme, occlusal forces would be borne predominantly by ____ teeth

Answer 28

posterior

Question 29

Supporting or centric holding cusps

Answer 29

lingual cusps of Mx posterior teeth
-buccal cusps of Md posterior teeth
(when teeth are in normal alignment)

Question 30

Non-supporting or non-centric holding cusps

Answer 30

Buccal cusps of Mx posterior teeth and lingual cusps of Md posterior teeth