Aetiology of Malocclusion I

Question 1

General aetiological factors for malocclusion (3)

Answer 1

1. SKELETAL
   - Size
   - Shape
   - Relative positions of upper + lower jaws
2. MUSCULAR
   - Form and function of the muscles that surround the teeth (lips, cheek + tongue)
3. DENTOALVEOLAR
   - Size of the teeth in relation to size of the jaws

Question 2

List the components of the facial skeleton (3)

Answer 2

1. Maxillary base
2. Mandibular base
3. Maxillary + mandibular alveolar processes

Question 3

What is the maxillary complex attached to?

Answer 3

Anterior cranial base

Question 4

What does the mandible articulate with?

Answer 4

Posterior cranial base in the glenoid fossa

Question 5

Possible environmental factors for aetiology of skeletal variation (3)

Answer 5

1. Masticatory muscles
2. Mouth breathing
3. Head posture

Question 6

Test for class I skeletal jaw relationship

Answer 6

Anteroposterior plane

- Scissor fingers

Question 7

Whats a normal cranial base angle?

Answer 7

130-135 degrees

Question 8

What is lateral cephalometry

Answer 8

Standardised lateral radiographs of the face and the base of the skull

Question 9

Whats the SNA value

Answer 9

Maxilla to the SN line (anterior cranial base)

Question 10

Whats the SNB value

Answer 10

Relates to the mandible (B) to the anterior cranial base