Cephalometric

Question 1

Describe the reasons why a lat ceph is used in orthodontics?

Answer 1

A lateral cephalometric is used to measure & assess the dental, skeletal relationships in vertical and anterior-posterior dimensions.

The cranial base is considered a stable landmark from age 7 and this plane is known as SN (sella & nasion)

Lateral cephalograms are standardised to compare one patient at different time points

Question 2

Describe how a lat ceph is taken.

Answer 2

The patients head should be in a natural head posture with the Frankfort plane horizontal. A head positioner is used, ear rods fit into the patients external auditory meatus. The xray source is 5 feet from the patient with the film 1 foot behind the midsagittal plane.

Question 3

What is the purpose of the scale on the radiograph?

Answer 3

A scale must be on the radiograph as there is a magnification of 7-10%, This allows accurate measurements calculated.

Question 4

Add the appropriate cephalometric measurement/ plane that describes the following relationships:
e.g. inclination of upper incisors = UI/MxP

Position of the maxilla in relation to the cranial base

Answer 4

SNA

Question 5

Add the appropriate cephalometric measurement/ plane that describes the following relationships:
e.g. inclination of upper incisors = UI/MxP

Position of the mandible to the cranial base

Answer 5

SNB

Question 6

Add the appropriate cephalometric measurement/ plane that describes the following relationships:
e.g. inclination of upper incisors = UI/MxP

Relation of the maxilla to the mandible in a AP dimension

Answer 6

SNA-SNB=ANB

Question 7

Add the appropriate cephalometric measurement/ plane that describes the following relationships:
e.g. inclination of upper incisors = UI/MxP

Measurement of the vertical dimension

Answer 7

MMPA

Question 8

Add the appropriate cephalometric measurement/ plane that describes the following
relationships:
e.g. inclination of upper incisors = UI/MxP

Inclination of lower incisors

Answer 8

Li/MnP

Question 9

explain the Wits Analysis

Answer 9

Whit analysis assess the relative AP position of the mandible to the maxilla. This does not involve the crainial base. It compares the distance between perpendicular lines. A point to the occlusal plane (AO) and B point to the occlusal plane (BO).

Normal distance between AO and BO should be
+1mm ±1.9mm) in males
0mm (± 1.77mm) in females

Limitation of this analysis is that the occlusal plane can change with treatment