Cephalometrics

Question 1

What is “G”

Answer 1

Soft Tissue Glabella: The most anterior point of the forehead

Question 2

What is “N”

Answer 2

Soft Tissue Nasion: The deepest point of the concavity in the midline between the forehead and the nose

Question 3

What is “Pn”

Answer 3

Pronasale: The most anterior point of the nose

Question 4

What is “Sn”

Answer 4

Subnasale: The point at which the columella of the nose merges with the upper lip in the midsagittal plane

Question 5

What is “Ls”

Answer 5

Labrale superior: the mucocutaneous border of the upper lip vermilion

Question 6

What is “Sts”

Answer 6

The lowest point of the vermilion of the upper lip

Question 7

What is “Sti”

Answer 7

Stomion inferius: the uppermost point of the lower lip vermilion

Question 8

What is “Li”

Answer 8

Labrale inferior: the mucocutaneous border of the lower lip

Question 9

What is “Pog”

Answer 9

Soft tissue pogonion: the most anterior point of the chin in the midsagittal plane

Question 10

What is “Me”

Answer 10

Soft tissue menton: the lowest point on the contour of the soft tissue chin, found by dropping a perpendicular line from a horizontal line through the skeletal menton

Question 11

What is 1.

Answer 11

Facial Plane: Extends from “N” to “Pog”

Question 12

What is 2.

Answer 12

Upper facial plane: extends from “G” to “Sn”

Question 13

What is 3.

Answer 13

Lower facial plane: extends from “Sn” to “Pog”

Question 14

What is 4.

Answer 14

S-Line: Formed by connecting “Pog” to a point midway between “Pn” and “Sn”

Question 15

What is 5.

Answer 15

E-Line: extends from “Pn” to “Pog”

Question 16

What should the ratio of the middle facial third to the lower facial third be?

Answer 16

1:1

Question 17

When making soft tissue measurements on a lateral ceph, what plane should the measurements be perpendicular to?

Answer 17

Frankfurt Horizontal Plane (Porion to Orbitale)

Question 18

What is the average upper lip length for males and females?

Answer 18

Upper lip length measured from Subnasale to Stomion Superius

20 +/- 2 mm Females
22 +/- 2 mm Males

Question 19

What is the relationship between lip length and maxillary incisor exposure?

Answer 19

Increased upper lip length = decreased maxillary incisor exposure and associated with vertical maxillary deficiency

Decreased upper lip length = increased maxillary incisor exposure and associated with vertical maxillary excess

Question 20

What effect does the lip length have on smile and lip seal?

Answer 20

Increased lip length results in toothless smile and adequate lip seal

Decreased lip length results in gummy smile and increased interlabial gap

Question 21

What is the lower lip/chin length, where is it measured?

Answer 21

The lower lip/chin length is measured from Stomion inferius to menton and it should be 40 +/- 2 mm for females and 44 +/- 2 mm for males

Question 22

What should the ratio of the upper lip length to the lower lip/chin length be?

Answer 22

the upper lip length should be apx half the length of the lower lip and chin

Question 23

What is a normal interlabial gap when lips are relaxed

Answer 23

1 - 3 mm

Question 24

What is a larger interlabial gap (>4 mm) indicative of?

Answer 24

Lip incompetence due to vertical maxillary excess

Question 25

How much of the maxillary incisors should be visible at rest?

Answer 25

When the patient's lips are relaxed, 1 - 4 mm of the maxillary incisors should be visible under the upper lip. Lack of tooth exposure may be an indication of maxillary vertical deficiency, more than 4 mm of tooth exposure may indicate vertical maxillary excess.

Question 26

What should the upper lip vermilion be in relation to the lower lip vemilion?

Answer 26

The upper lip vemilion height should be 25% less than the lower lip vermilion height. Vermilion heights may vary depending on race

Question 27

What is a possible cause of increased lower lip vermilion exposure?

Answer 27

Lower lip eversion caused by lip incompetence in patients with vertical maxillary excess. The lower lip is also often everted in Class II deep bite cases, or Class II, division 1 cases where the lower lip is rolled outward by the maxillary incisors