Cephalometrics Flashcards
What is “G”
Soft Tissue Glabella: The most anterior point of the forehead
What is “N”
Soft Tissue Nasion: The deepest point of the concavity in the midline between the forehead and the nose
What is “Pn”
Pronasale: The most anterior point of the nose
What is “Sn”
Subnasale: The point at which the columella of the nose merges with the upper lip in the midsagittal plane
What is “Ls”
Labrale superior: the mucocutaneous border of the upper lip vermilion
What is “Sts”
The lowest point of the vermilion of the upper lip
What is “Sti”
Stomion inferius: the uppermost point of the lower lip vermilion
What is “Li”
Labrale inferior: the mucocutaneous border of the lower lip
What is “Pog”
Soft tissue pogonion: the most anterior point of the chin in the midsagittal plane
What is “Me”
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
What is 1.
Facial Plane: Extends from “N” to “Pog”
What is 2.
Upper facial plane: extends from “G” to “Sn”
What is 3.
Lower facial plane: extends from “Sn” to “Pog”
What is 4.
S-Line: Formed by connecting “Pog” to a point midway between “Pn” and “Sn”
What is 5.
E-Line: extends from “Pn” to “Pog”
What should the ratio of the middle facial third to the lower facial third be?
1:1
When making soft tissue measurements on a lateral ceph, what plane should the measurements be perpendicular to?
Frankfurt Horizontal Plane (Porion to Orbitale)
What is the average upper lip length for males and females?
Upper lip length measured from Subnasale to Stomion Superius
20 +/- 2 mm Females
22 +/- 2 mm Males
What is the relationship between lip length and maxillary incisor exposure?
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
What effect does the lip length have on smile and lip seal?
Increased lip length results in toothless smile and adequate lip seal
Decreased lip length results in gummy smile and increased interlabial gap
What is the lower lip/chin length, where is it measured?
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
What should the ratio of the upper lip length to the lower lip/chin length be?
the upper lip length should be apx half the length of the lower lip and chin
What is a normal interlabial gap when lips are relaxed
1 - 3 mm
What is a larger interlabial gap (>4 mm) indicative of?
Lip incompetence due to vertical maxillary excess
How much of the maxillary incisors should be visible at rest?
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.
What should the upper lip vermilion be in relation to the lower lip vemilion?
The upper lip vemilion height should be 25% less than the lower lip vermilion height.
Vermilion heights may vary depending on race
What is a possible cause of increased lower lip vermilion exposure?
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
