W13 - Cepholometrics - Abdalla

Question 1

Features of the cephalostat (3)

Answer 1

• Xray machine at a fixed distance from pt
• Taken in a standardised orientation - natural head position
• Variations in distance from tube to patient allows different magnification (include scale in the view)

Question 2

What is the aluminium wedge used for in a cephalostat

Answer 2

Absorbs excess radiation and allows for visualisation of soft tissues

Question 3

Tip to achieve neutral head position

Answer 3

Ask patient to look into their own eyes in the mirror

Question 4

How is magnification calculated

Answer 4

Question 5

What is the goal of cephalometric analysis

Answer 5

Objectively measure the relationship between the 5 major funcitonal parts of the face

1. Cranium and cranial base
2. Maxilla
3. Mandible
4. Maxillary dentition
5. Mandibular dentition

Allows you to see the actual parts responsible for malocclusion and by what margin

Question 6

What 2 points make up the cranial base

Answer 6

Nasion (Na) and Sella (S)

Question 7

What are these two points

Answer 7

Na: anterior point of the intersection btw nasal and frontal bones

S: mid point of the sella turcica cavity

Question 8

What are the 3 important maxillary landmarks on ceph

Answer 8

Anterior Nasal Spine (ANS)

Posterior Nasal Spine (PNS)

Point A: innermost point on contour of premaxilla, btw ANS and incisor

Question 9

What are the 4 mandiblar landmarks

Answer 9

Point B: innermost point of contour between chin and incisor

Pogonion: most anterior point of chin

Menton: most inferior / bottom of chin

Gonion: corner of ramus / mandible

Question 10

What two teeth are important for landmarks

Answer 10

Upper/lower incisors

Upper/lower first molars

Question 11

What angle is used to describe the sagittal relationship

Answer 11

ANB angle

• normal range 3 +- 2
• (1-5)

Question 12

What ANB angles indicate malocclusion

Answer 12

ANB = 3 degrees → class 1

>3 degrees → class 2

<3 degrees → class 3

Question 13

What angle is used to assess maxilla in relation to cranial base? Normal range?

Answer 13

SNA

Normal is 81 degrees +- 3

Question 14

What SNA angles mean mx malocclusion

Answer 14

Question 15

What angle is used to assess the mandible in relation to cranial base? normal range?

Answer 15

SNB angle

78 degrees +- 3

Question 16

What SNB angles indicate md malocclusion

Answer 16

Question 17

What are the SNA and SNB angles used for? What is the average angle bewteen the two?

Answer 17

used to establish the relationship between maxilla and mandible to the cranial base

• SNA average = 81 degrees
• SNB average = 78 degrees
• Mx - md = 3 degrees

Question 18

Skeletal class? Due to?

Answer 18

Class 2 due to retrognathic mandible

Question 19

Skeletal class? Due to?

Answer 19

Class 3 due to prognathic mandible

Question 20

Skeletal class? Due to?

Answer 20

Class 3 due to retrognathic maxilla

Question 21

What is MMPA? Normal angle?

Answer 21

Maxilla/Mandible plane angle

normal is 27 degrees

+- 4 degrees

Question 22

What MMPA angles are brachyfacial and dolichofacial?

Answer 22

Brachy = <23 degrees

Normal = 27 degrees

Dolicho = >31 degrees

Question 23

What are the angles for maxillary retroclined, normal and proclined incisors

Answer 23

Retroclined <103 degrees

Normal 109 degrees

Proclined >115 degrres

Question 24

What are the angles for mandibular retroclined, normal and proclined incisors

Answer 24

Question 25

Question 26

When is the ideal time to do treatment in regards to vertebral development / puberty

Answer 26

CS3 - pubertal growth spurt soon to come

Question 27

What is the issue with using CBCT for ortho?

Answer 27

Due to 3d ability, there are no stable landmarks

• cannot superimpose images

Question 28

Answer 28

CS3 best time

Question 29

Ask laura about this slide