Cephalometric analysis practical

Question 1

How do you clically assess skeletal pattern

Answer 1

use all 3 planes

1) anterior posterior
2) vertical
3) transverse

Question 2

ideal relationship of skeletal pattern anterior posterioe (class 1)

Answer 2

mandible set just back from maxilla and forhead

Question 3

classes of anterior posterior skeletal patterns

Answer 3

1 mandible just set back from mx and forehead
2 mandible set back with, maxilla alinged
3 top jaw set forwards from forehead, mandible too far forwards

Question 4

Idel vertical plane

Answer 4

frankfort mandibular planes angl

• lines coverage at back of head
• face is roughly in equal 3rs (see pic )

Question 5

non ideal FMPAs(vertical skeltal patthen)

Answer 5

lines converge further abck from head
- reduced FMPA
- lower anterior face height
- deep overvite
lines converge forwards from the head
- increased FMPA
- lower face height icreased
- generally have anterior open bite

Question 6

uses of cephalomenry

Answer 6

diagnosis
treatment planning
measure growth
assess treatment

Question 7

limits of cepthalmetry

Answer 7

slightly magnified (2d image of 3D object)
not a science
sources of error

Question 8

types of errors that can occur

Answer 8

systematic bias

random

Question 9

errors affecting validiy

Answer 9

1) positioning of head in cephalostat
2) magnification and distortion
3) 3D object projected to 2D image – projection errors
4) landmarks defined for convenience rather than anatomical validity
- eg if you change the teeth position will change anatomical points that you measure against
5) remodelling (upper incisors)

Question 10

errors affecting reproducability

Answer 10

1) blurring of image due to movement during exposure
2) variation in film contrast
3) thickness of pencil
4) perceptive limits of human eye
5) inconsistency of the human eye

Question 11

Growth predication problems

Answer 11

adding of average amounts (averge is very variable)
- not accurate
- skeletal pattern remians the same in 60%
reference point may chanege

Question 12

measurements that are taken in cephalometry

Answer 12

sella
nasion
A point
B point
anteriot nasal spine
posterior nasal spine
menton
gonion

Question 13

sella

Answer 13

midpoint of the pituitary fossa

Question 14

naison

Answer 14

most anterior point on the frontonasal suture

Question 15

what does the line between N and S equal

Answer 15

roughly anterior cranial base

stable landmark

Question 16

A point

Answer 16

deepest point on anterior surface of maxilla

Question 17

B point

Answer 17

deepest concavity on the antierior surface of the mandible

Question 18

line between Aand B points

Answer 18

used to measure the top jaw to the lower jaw

Question 19

anterior nasal spine

Answer 19

tip of bony anterior nasal spine

Question 20

posterior nasal spine

Answer 20

tip of posteiro nasal spine

usually near last molar tooth

Question 21

menton

Answer 21

lower most point on the mandibular symphysis

Question 22

gonion

Answer 22

constructed point

at the intersection of the lines tangent to the postieor margin of the ascending ramus and the md symphysis

Question 23

teeth markings for cephlometrics

Answer 23

upper incisor (apex and tip)
lower incisor (apex and tip_

Question 24

final measurements for cephalometrics

Answer 24

SNA
SNB
AMB
MMPA

Question 25

SNA

Answer 25

averge 81 degrees

indicates position of mx relative to cranial base

Question 26

SNB

Answer 26

indicate position of mandible relative to cranial base

Question 27

AMB

Answer 27

relationship of the 2 jaws to each other
less then 2 indicates class 3

Question 28

upper incisors degree of proclination

Answer 28

ANS to PNS
over 115 incisors are proclined
less than 104 incisors are retro clined

Question 29

lower incisors degree of inclination

Answer 29

M and Go plane, long axis of lower incisors
greater tha 94 proclined
less than 90 retero clined