Lab 3

Question 1

• a line connecting S to Na

Answer 1

Sella-Nasion (S-N)

Question 2

• a line connecting Po to Or

Answer 2

Frankfort Horizontal (FH)

Question 3

• a line connecting Go to Me

Answer 3

Mandibular Plane (MP)

Question 4

• a line connecting Se to Pg

Answer 4

Y-axis (Y)

Question 5

• a line connecting Na to ANS

Answer 5

Upper Anterior Facial Height (UAFH)

Question 6

• a line connecting ANS to Me

Answer 6

Lower Anterior Facial Height (LAFH)

Question 7

• a line connecting Na to A

Answer 7

• Nasion-A point (Na-A)

Question 8

• a line connecting Na to B

Answer 8

• Nasion-B point (Na-B)

Question 9

•These 2 angle indicates the A-P
position of the maxilla relative to
the cranial base.

Answer 9

Sella- Nasion-A point

NA-FH

Question 10

SNA angles:
•>\_\_\_ - protrusive or prognathic 
maxilla
•< \_\_\_\_ - deficient or retrognathic
maxilla

Answer 10

85°

79°

Question 11

NA-FH angles
•>___ - protrusive or prognathic maxilla
•

Answer 11

94

86

Question 12

•A true vertical line dropped from N and
horizontal distance parallel to this true
vertical line is measured from A- Point.
•This measurement describes the position
of apical base of Maxilla in relation to
Nasion.

Answer 12

N Perpendicular to A-Point

Question 13

is the most anterior measure point of the mandibular apical base.
•This angle expresses the A-P position of the mandible relative to the cranial base using B-point as a cephalometric landmark.

Answer 13

•Sella - Nasion - B point

Question 14

SNB measurements:
•>___° - prognathic mandible
•

Answer 14

82

76°

Question 15

, measures the degree of protrusion and retrusion of the chin but uses Frankfort Horizontal as a reference plane.
• It also indicates the horizontal position of the mandible relative to the cranial base.

• Note: Using all three angles and both reference planes, the clinician can make a good evaluation of the position of the mandible and determine whether the mandible is normal, protrusive or retrognathic.
• In addition, the prominence of the chin may also be determined.
• It is possible to have a retrognathic mandible but prominent chin.

Answer 15

• SN-Pg

Question 16

• SN-Pg measurements
• >__ - prognathic mandible
•

Answer 16

91°

83°

Question 17

• This angle represents the extent of chin prominence relative to the reference plane SN.
• It also indicates the A-P position of the mandible relative to the cranial base using pogonion as landmark.

Answer 17

SN- Pog

Question 18

SN-Pog measurements
•>__ - prognathic mandible
•

Answer 18

83°

77°

Question 19

•It is obtained by measuring the 
horizontal distance between Pog and 
Nasion perpendicular.
•This measurement describes the 
position of the Mandibular Chin in 
relation to Nasion.

Answer 19

N Perpendicular to Pog

Question 20

The ___ angle measures the relative
position of the maxilla to mandible.
= SNA - SNB

Answer 20

ANB

Question 21

A _____ (+ or -) ANB angle indicates that the
maxilla is positioned anteriorly relatively to
the mandible. • Skeletal Class I or Class II.

Answer 21

positive

Question 22

A _____ (+ or -) ANB angle indicates that the
maxilla is positioned posteriorly relative to
the mandible.• Skeletal Class III.

Answer 22

negative

Question 23

•Drawing occlusal plane (OP), which is a line
through maximum cuspal Interdigitation of the
molars and premolars.
•Drawing a perpendicular line from Point A on
maxilla and Point B on mandible.
•The point of contact on the occlusal plane from
A and B are labelled AO and BO respectively.

Answer 23

Wits Appraisal

Question 24

•In normal occlusion BO is 1 mm ____ to point AO.

Answer 24

anterior

Question 25

•In skeletal _____ point BO is located posterior to point AO.

Answer 25

class II

Question 26

•In skeletal _____ point BO is anterior of point AO.

Answer 26

class III

Question 27

The ______ is represented by a line which bisects the distance between the left and right mandibular lower borders and connects anteriorly with Menton. -can also be used as a measure of mandibular growth and lower facial growth direction.

Answer 27

mandibular plane

Question 28

* Angle between Sella –Nasion and the line connecting Sella to Gnathion. * is an estimate of mandibular growth direction. • A larger angle indicates a more downward and vertical growth direction of the mandible. * A smaller angle indicates a more horizontal and anterior growth direction of the mandible. * It also indicates the degree of downward and forward position of the chin in relation to the upper face.

Answer 28

Y-Axis

Question 29

Nasion to ANS

Answer 29

UAFH

Question 30

ANS to menton

Answer 30

LAFH

Question 31

UAFH/LAFH ratio <0.8 indicates a greater LAFH, or ____ lower anterior face height.

Answer 31

longer

Question 32

UAFH/LAFH ratio >0.8 indicates a smaller LAFH, or ______ lower anterior face height.

Answer 32

shorter

Question 33

•This angular measurement determines the inclination of the central incisor relative to the anterior cranial base. •A greater than average angle indicates proclination (labioversion) of incisors as often seen in Class II/D1. •A smaller than average angle indicates upright or retroclined (lingually inclined) incisors as often seen in Class II/D2.

Answer 33

U1 to SN

Question 34

•The relationship of the maxilary central incisor to the N-A reference line is used to establish the position of the maxillary incisors relative to the maxillary apical base. •Both the inclination of the long axis of the incisor to the line and the distance of the labial surface of the incisor in front of the line are measured. •The inclination indicates whether the tooth has been tipped to its position or moved bodily.

Answer 34

U1 to NA

Question 35

* The millimeter distance establishes the prominence of the incisors relative to the supporting bone. * Labially inclined (proclined) incisors will have a greater than average angular and linear measurement (Class II / D1). * Upright (retroclined) incisors will have a smaller than average angular and linear measurement (Class II /D2). * Positive values are recorded if the labial surface of the incisor is anterior to the NA line, negative values if posterior.

Answer 35

Nasion- A point

Question 36

•The relationship of the mandibular central incisor to the N-B reference line is used to establish the position of the mandibular incisors relative to the mandibular apical base. •Both the inclination of the long axis of the incisor to the line and the distance of the labial surface of the incisor in front of the line are measured. •The inclination indicates whether the tooth has been tipped to its position or moved bodily.

Answer 36

L1 to NB

Question 37

• The millimeter distance establishes the prominence of the incisors relative to the supporting bone. • Labially inclined (proclined) incisors will have a greater than average angular and linear measurement (Class II / D1). • Upright (retroclined) incisors will have a smaller than average angular and linear measurement (Class II /D2). • Positive values are recorded if the labial surface of the incisor is anterior to the NB line, negative values if posterior.

Answer 37

Nasion - B point

Question 38

``` •It defines the axial inclination between the mandibular incisor and the inferior border of the mandible. •The more the incisor is labially inclined, the greater the angle. ```

Answer 38

L1- MP | •IMPA (Incisor Mandibular Plane Angle).

Question 39

``` •Measures the relative position along the long axis of the most anteriorly positioned maxillary and mandibular central incisors. •It determines the degree of labial inclination of the incisors. •The more proclined the incisors are, the less the angle. •The more retroclined the incisors are, the more the angle. ```

Answer 39

Inter-incisal Angle

Question 40

runs from the tip of the nose to the soft tissue Pogonion. •Lips are analyzed depending on the distance of them from it. •Both lips should be behind this line. • Upper: 2 -3 mm • Lower: 1 –2 mm

Answer 40

E- line