Aetiology of Malocclusion Flashcards

1
Q

what are the 3 broad aetiologies of malocclusions

A

Skeletal - size, shape and relative position of upper and lower jaws
Muscular - form and function of the muscles that surround the teeth e.g lips, tongue and cheeks
Dento-alveolar - size of teeth in relation to size of jaws

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Cranial base angle

A

angle formed where the anterior cranial base and the posterior cranial base meet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Class I occlusion

A

‘normal occlusion’
maxilla slightly in front of mandible
lower incisors occlude or lie directly below the upper central cingulum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Class II occlusion

A

‘overjet’
mandible is posterior to maxilla
lower incisor edges lie posterior to the upper central cingulums
division 1 = upper incisors are proclined or normal
division 2 = upper incisors retroclined

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Class III occlusion

A

‘reversed overjet’
mandible is anterior to the maxilla
lower incisor edges lie anterior to the upper central cingulums

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

dento alveolar compensation

A

refers to movement of dento alveolar structures to disguise skeletal discrepancies
e.g upper incisors procline and lower incisors retrocline in class IIIs making reverse overjet appear reduced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Frankfort plane

A

lower orbital rim to the superior border of the external acoustic meatus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

mandibular plane

A

lower border of mandible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

where do the mandibular plane and the frankfort plane usually meet (in patients with normal skeletal relationship)

A

external occipital protuberance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

where is upper anterior face height measured from and to

A

glabella to base of nose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

where is lower anterior face height measured from and to o

A

base of nose to inferior surface of chin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the average ratio of lower anterior face height : total anterior face height

A

TAFH = LAFH + UAFH (glabella to inferior border of chin)
average = 50% of TAFH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the average FMPA angle and what is this

A

frankfort mandibular plane angle
usually 27 degrees +/- 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

describe the skeletal tendencies of a ‘long facial type’

A

steeply inclined mandibular plane
Anterior open bite tendency
backward mandibular growth rotation
FMPA usually increased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

describe the skeletal tendencies of a ‘short facial type’

A

parallelism of jaws
deep overbite tendency
forward mandibular growth rotation
FMPA usually decreased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Name 2 dento-alveolar discrepancies and a potential cause

A

Crowding - small jaws and normal teeth or macrodontia
Spacing - large jaws and normal teeth of microdontia