Cephalometry Flashcards

0
Q

What is sella (S)?

A
  • Craniofacial reference point

* The mid-point of the cavity of sella turcica

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1
Q

Craniofacial reference points for cephalometric analysis include…

A
  • Sella (S)
  • Nasion (N)
  • Porion (Po)
  • Orbitale (Or)
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2
Q

What is nasion (N)?

A
  • Craniofacial reference point

* Anterior point of the intersection between the nasal and frontal bones

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3
Q

What is porion (Po)?

A
  • Craniofacial reference point
  • Midpoint of the upper contour of the external auditory canal (anatomic porion)
  • Or, midpoint of the upper contour of the metal ear rod of the cephalometer (machine portion)
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4
Q

What is orbitale (Or)?

A
  • Craniofacial reference point

* Lowest point on the inferior margin of the orbit

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5
Q

Maxillary reference points for cephalometric analysis includes…

A
  • Anterior nasal spine (ANS)
  • Posterior nasal spine (PNS)
  • Point (A)
  • Incision superius (Is)
  • Apex superius (As)
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6
Q

What is anterior nasal spine (ANS)?

A
  • Maxillary reference point

* The tip of the anterior nasal spine

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7
Q

What is the posterior nasal spine (PNS)?

A
  • Maxillary reference point

* Tip of the posterior spine of the palatine bone, at the junction of the hard and soft palates

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8
Q

What is point A?

A
  • Maxillary reference point

* Innermost point on the contour of the premaxilla between anterior nasal spine and the incisor tooth

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9
Q

What is the incision superius (Is)?

A
  • Maxillary reference point

* Incisal edge of the maxillary incisor

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10
Q

What is the apex superius (As)?

A
  • Maxillary reference point

* Root tip of maxillary central incisor

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11
Q

Mandibular reference points for cephalometric analysis includes…

A
  • Gonion (Go)
  • Pogonion (Pog)
  • Gnathion (Gn)
  • Menton (Me)
  • B (point)
  • Incision inferius (Ii)
  • Apex inferius (Ai)
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12
Q

What is gonion (Go)?

A
  • Mandibular reference point

* Midpoint of the contour connecting the ramus and body of the mandible

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13
Q

What is pogonion (Pog)?

A
  • Mandibular reference point

* Most anterior point on the contour of the chin

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14
Q

What is gnathion (Gn)?

A
  • Mandibular reference point

* Center of the inferior point on the mandibular symphysis (i.e. the bottom of the chin)

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15
Q

What is menton (Me)?

A
  • Mandibular reference point

* The most inferior point on the mandibular symphysis (i.e. the bottom of the chin)

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16
Q

What is point B?

A
  • Mandibular reference point

* Innermost point on the contour of the mandible between the incisor tooth and the bony chin

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17
Q

What is the incision inferius (Ii)?

A
  • Mandibular reference point

* Incisal edge of the mandibular incisor

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18
Q

What is the apex inferius (Ai)?

A
  • Mandibular reference point

* Root tip of mandibular central incisor

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19
Q

Soft tissue reference points for cephalometric analysis includes…

A
  • Pronasale (Pn)
  • Labrale inferior (Li)
  • Labrale superior (Ls)
  • Sabnasale (Sn)
  • Chin (soft)
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20
Q

What is the pronasale (Pn)?

A
  • Soft tissue reference point

* Most forward point of the tip of the nose

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21
Q

What is the labrale inferior (Li)?

A
  • Soft tissue reference point

* Most forward point of the lower lip

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22
Q

What is the labrale superior (Ls)?

A
  • Soft tissue reference point

* Most forward point of the upper lip

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23
Q

What is the sabnasale (Sn)?

A
  • Soft tissue reference point

* Bottom point of nose (on the curve from upper lip to nose)

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24
Q

What is the chin (soft)?

A
  • Soft tissue reference point

* Most forward point of the soft tissue chin

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25
Q

Define: a standardized technique of studying the skull by means of laterally oriented head radiographs. It uses living individuals.

A

Cephalometry

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26
Q

Goals for cephalometric analysis include…

A
  • Orthodontic and orthognathic diagnosis and treatment planning
  • Orthodontic treatment outcomes evaluation
  • Study and monitor the growth of dentofacial structures
  • Functional study of jaw movement
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27
Q

Cephalometric analysis steps…

A
  1. Take cephalometric x-ray film + tracing paper
  2. Cephalometric film tracing (hard vs. soft tissues)
  3. Determine reference points and planes
  4. Measure various variables (angular vs. linear)
  5. Compare the measures with norms –> diagnosis
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28
Q

The cephalometric equipment consists of…

A
  • Cephalostat (head holder)

* X-ray source

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29
Q

When positioning the patient on the cephalostat, the position of the Frankfort Horizontal Plane should be…

A

The Frankfort Horizontal Plane should be parallel to the floor.

30
Q

Things to pay attention to for cepholographs…

A
  • Radiographic image is always larger than the object being radiographed.
  • Superimposition of all bilateral structures occurs.
  • For the mandible, in a correctly positioned film, the lower border of the body on the side closer to the film is always superior to the image of the body in a distant from the film.
  • The posterior border of the ascending rams on the side closer to the film is always anterior to the image of the other rams.
31
Q

Roentgen error includes…

A
  • Out of focus
  • Movement
  • Half shadow phenomenon
  • Secondary radiation
  • Distortion
  • Double contours
  • Enlargement
32
Q

Anatomical landmarks on a ceph x-ray can be…

A
  • Skeletal points
  • Dental points
  • Soft tissue points
33
Q

Artificial points on a cep x-ray are those that…

A

We construct by bisecting structures and projecting where it would be.

34
Q

Horizontal planes for a ceph include…

A
  • Anterior cranial base
  • Frankfort horizontal plane
  • Occlusal plane
  • Palatal plane
  • Mandibular plane (3)
35
Q

Anterior cranial base plane…

A
  • Horizontal plane

* Nasion –> Sella

36
Q

Frankfort horizontal plane…

A
  • Horizontal plane
  • Orbitale –> Porion
  • During tracings, make Frankfort Horizontal Plane parallel to the floor
37
Q

Palatal plane…

A
  • Horizontal plane

* Anterior nasal spine –> posterior nasal spine

38
Q

Mandibular plane…

A
• Horizontal plane
• There are three:
     - Gonion --> gnathion
     - Gonion --> menton
     - Lower border of the mandible
39
Q

Occlusal plane…

A
  • Horizontal plane
  • Involves bisecting
  • Bisect tip of upper and lower incisors, and find the highest point of posterior contact.
40
Q

Vertical planes include…

A
  • NA, NB plane
  • Y-axis
  • McNamara line
  • Upper 1 axis
  • Lower 1 axis
41
Q

NA, NB planes…

A
  • Vertical plane
  • Nasion-point A, Nasion-point B
  • Look at the difference between the two
42
Q

Y-axis plane…

A
  • Vertical plane
  • sella –> gnathion.
  • Determines the direction of growth
43
Q

McNamara line…

A
  • Vertical plane
  • Perpendicular to the Frankfort horizontal plane
  • Passes through the nasion
44
Q

Upper 1 axis plane…

A
  • Vertical plane

* Tip to root of maxillary incisor

45
Q

Lower 1 axis plane…

A
  • Vertical plane

* Tip to root of mandibular incisor

46
Q

Commonly used cephalometric measurement systems include…

A
  • Downs analysis
  • Riedel analysis
  • Steiner analysis
  • Ricketts analysis
  • Wits appraisal
  • McNamara analysis
  • Tweed analysis
47
Q

Downs analysis…

A

Most commonly used analysis

48
Q

Riedel analysis…

A

Second most commonly used analysis

49
Q

Steiner analysis…

A
  • Used at RSDM
  • Steiner created a sophisticated analysis based on one patient that he deemed ideal. He based all the information from that one patient.
50
Q

Wits appraisal…

A
  • Specific to the position of maxilla and mandible in regards to bone.
  • This is the only thing it gives, and it’s the best one.
  • Line from A perpendicular to the occlusal plane
  • Line from B perpendicular to the occlusal plane
  • Value of +3 indicates that the maxilla is too far forward, mandible too far back, or both.
51
Q

McNamara analysis…

A
  • Used in Michigan

* Created by an influential and respected orthodontist

52
Q

SNA…

A
  • An angle formed by sella-nasion-point A
  • Orthogonathic maxilla = 82 deg (Normal value)
  • Prognathic maxilla = >86 deg
  • Retrognathic maxilla = <78 deg
53
Q

SNB…

A
  • An angle formed by sella-nasion-point B
  • Orthogonathic mandible = 80 deg (normal value)
  • Prognathic mandible >84 deg
  • Retrognathic mandible <76 deg
54
Q

ANB…

A
  • ANB = SNA-SNB
  • Class I skeletal pattern = +2 deg (normal value)
  • Class II skeletal pattern >6 deg
  • Class III skeletal pattern <-1 deg
55
Q

SN-GoGn…

A
  • Vertical relationship
  • Angle between Go-Gn (mandibular plane) and SN plane
  • Determines if patient is a vertical or horizontal grower
  • Standard is 33 deg
56
Q

FMA angle…

A
  • Vertical relationship
  • Angle between Frankfort plane and Go-Gn (mandibular plane)
  • Brachyfacial patient will have small or parallel angle of mandible to Frankfort horizontal plane.
  • Average is 23 deg
57
Q

Y-axis angle…

A
  • Vertical relationship
  • Angle between Y-axis (Sella –> Gnathion) and Frankfort horizontal plane
  • A small angle indicates a brachyfacial, horizontal grower, or class III.
  • Average is 59 deg
58
Q

U1-SN…

A
  • Maxillary dentition
  • An angle between “upper central incisor” and SN plane
  • Increased by tongue thrusting, thumb sucking
  • Average is 102 deg
59
Q

U1-NA…

A
  • Maxillary dentition
  • Angle between upper central incisor and “NA plane”
  • Average = 24 deg
60
Q

U1-NA(mm)…

A
  • Distance between U1 and NA, measured in mm.
  • 0 = incisor tip on line
  • negative = behind
  • Positive = in front
  • Average = 4mm
61
Q

IMPA…

A
  • Mandibular dentition
  • Angle between “lower central incisor” (L1) and mandibular plane
  • If too large, angle with the Frankfort horizontal plane would be smaller
  • Used by Tweed to aim for a balanced face
  • Average = 90 deg
62
Q

L1-NB…

A
  • Average = 25 deg
  • Mandibular dentition
  • Angle between “lower central incisor” (L1) and “NB plane”
63
Q

L1-NB(mm)…

A
  • Average = 4 mm
  • Mandibular dentition
  • Distance between “lower central incisor” and “NB plane” in mm
64
Q

Nasiolabial angle…

A

• Soft tissue measurement
• Between “base of nose” and “upper lip”

65
Q

Esthetic line…

A
  • Soft tissue measurement
  • a line formed by tips of nose and tip of chin
  • Upper lip should be 1 mm behind this line
  • Lower lip touches line
66
Q

UFH (mm)…

A

• Soft tissue measurement
• upper facial height = from “N” to “ANS”
• LFH should be slightly greater than UFH.
- 55% and 45% respectively

67
Q

LFH (mm)…

A

• Soft tissue measurement
• lower facial height = from “ANS to “Me”
• LFH should be slightly greater than UFH.
- 55% and 45% respectively

68
Q

Mid-sagittal landmarks include..

A
  • Sella turcica: center of hypophyseal fossa
  • Nasion: junction of frontal and nasal bones
  • A-point: innermost curve from the maxillary anterior nasal spine to the crest of the maxillary alveolar process (usually opposite root tip of maxillary central incisor)
  • B-point: innermost curvature from chin to alveolar junction (usually opposite root tip of lower central incisor)
  • Pogonion: most anterior point on the contour of the chin
  • Menton: lowest point on the symphysis; determined by using a line tangential to the lower border of the mandible
  • Gnathion: most outward and everted point on the profile curvature of the symphysis of the mandible (located midway between pogonion and mention)
  • Basion: anterior margin of the foramen magnum
69
Q

Bilateral landmarks include…

A
  • Orbitale: lowest point on the inferior border of the left and right orbital rims
  • Gonion: middle of the curvature of the left and right angles of the mandible
  • Articulare: posterior borders of mandibular rami, intersecting with basilar portion of the occipital bone
  • Porion: point midway between the top of the image of the left and right ear-rods of the cephalometer
  • Pterygomaxillary fissure: projected onto palatal plane; anterior wall represents max tuberosity outline, posterior wall the anterior curve of the pterygoid process
  • Key ridge
70
Q

Superimposition is best done on this plane…

A
  • Sella-nasion plane
  • Relatively stable anatomic structure
  • Completed early in the developmental process
71
Q

Points and angles used in Steiner analysis…

A
  • SNA
  • SNB
  • ANB
  • Maxillary incisor to NB
  • Maxillary Incisor to NA
  • Mandibular incisor to NB
  • Mandibular incisor to Go-Gn
  • Maxillary incisor to palatal plane
  • Mandibular plane to SN
72
Q

Mandibular plane to SN…

A
  • > 38 deg –> open bite skeletal pattern
  • 32 deg –> normal vertical development
  • deep bite skeletal pattern