Cephalometric Analysis Flashcards

1
Q

Basics of Cephalometry

A

Invented simultaneously in 1931 US and Germany
Taken using standard method
Results in constant magnification

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2
Q

Skeletal pattern

A

Clinically assess in all 3 planes

Cephs used to assess AP and vertical

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3
Q

Class I

A

Nasium just behind upper lip, mandible behind

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4
Q

Class II

A

Nasium in line with upper lip, mandible far behind

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5
Q

Class III

A

Nasium between upper lip and mandible

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6
Q

Vertical (Frankfort Mandibular Planes Angle)

A

Average FMPA: lines converge at back of head
If way out back: reduced lower anterior face height (deep overbite)
If in front: increased lower face height (anterior open bite)

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7
Q

Uses

A

Diagnosis
Treatment planning
Measure (predict?) growth
Assess treatment

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8
Q

Limits of cephalometry

A

Slightly magnified, 2D representation of 3D object
Not a science
Use as guide not prescription
Many sources of error

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9
Q

Errors affecting validity

A

Positioning o head in cephalostat (random)
Magnification and distortion
3D object projected to 2D image (projection errors)
Landmarks defined for convenience rather than anatomical validity
Remodelling (upper incisors)

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10
Q

Errors affecting reproducibility

A

Blurring of image due to movement during exposure
Variation in film contrast
Thickness of pencil
Perceptive limits of human eye
Inconsistency in identification of landmarks

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11
Q

Growth prediction

A
Add average amounts
Not accurate
Skeletal pattern remains same in 60% of individuals, improves in 30% and gets worse in 10%
Stable reference point?
Serial radiographs show past growth
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12
Q

Sella (S)

A

Midpoint of pituitary fossa

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13
Q

Nasion (N)

A

Most anterior point on frontnasal suture

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14
Q

A point (A)

A

Deepest point on anterior surface of maxilla

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15
Q

B point (B)

A

Deepest concavity on anterior surface of mandible

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16
Q

SNA

A

81 +/- 2

Indicates position of maxilla relative to cranial base

17
Q

SNB

A

78 -/+ 2

Indicates position of mandible relative to cranial base

18
Q

ANB

A

2-4 degrees

Indicates relationship of maxilla and mandible to each other (skeletal relationship)

19
Q

ANS (anterior nasal spine)

A

Tip of bony anterior nasal spine

20
Q

PNS

A

Tip of the posterior nasal spine

21
Q

Menton (Me)

A

Lowermost point on mandibular symphysis

22
Q

Gonion (Go)

A

Constructed point, intersection of lines tangent to posterior margin of ascending ramus and mandibular symphysis

23
Q

MMPA

A

27 +/- 3

>30 more difficult to treat

24
Q

U1

A

Upper incisor

Apex and tip

25
Q

U1/ MaxP

A

109 +/-2

Indicates degree of proclination/ retroclination

26
Q

L1

A

Apex and tip of lower incisor

27
Q

L1/ MandPlane

A

92 +/-2
L1/ MandP + MMPA should = 120
Indicates degree of proclination/ retroclination