Cephalometrics / Computer Techniques 34% 18Q Flashcards
what is the Holdaway ratio?
1:1 ratio for distance btwn L1 to NB and PG to NB
what is the reference plane for the Rickett’s analysis?
frankfort horizontal
In the Rickett’s analysis, what is the facial axis?
angle formed btwn basion-nasion plane and the plane from foramen rotundum to gnathion (PTM to Gn)
In the Rickett’s analysis, the facial axis norm is ___ degrees. Greater numbers means the chin is _____________, and lesser means the chin is _____________.
90 deg
retrognathic
prognathic
In the Rickett’s analysis, describe the change in facial axis from ages 8-18
no change
In the Rickett’s analysis, what two lines form the facial angle?
FH & N-Pg
In the Rickett’s analysis, the facial angle is used to:
measure the degree of retrusion or protrusion of the lower jaw
In Rickett’s analysis, the average facial angle is ___ deg.
88
In the Rickett’s analysis, describe the change in facial angle from ages 8-18
increases with age
The mandibular plane angle ( increases / decreases ) with age
decreases
E-Line extends from soft tissue tip of nose to soft tissue _________
popgonion
The lower lip should be -___mm being E-plane for a 9 y/o
-1mm
Which plane does Frankfort horizontal most closely parallel?
palatal plane
What is the reference plane for the Downs analysis?
Frankfort horizontal
what is Broadbent registration (or point R) used for?
superimpositions
A line between which two points makes the facial plane?
NPg
AB to NPg relates denture bases to each other and the skeletal profile. If the number is negative, this reflects a Class ____ relationship, if the number is positive, this reflects a Class ___ relationship.
II
III
The Y axis is an angle created by __________________- to ___ - ___
Frankfort Horizontal to SGn
The average value of Y axis is ___ degrees. Numbers larger than this value indicate a class ___ relationship and numbers smaller than this value indicate a class ___ relationship.
59
class II
class III
When treating a class II, we want the Y axis to ( increase / decrease )?
decrease
How does the Y axis change as we age?
It remains constant
Which cephalometric value is thought to define mandibular growth direction?
Y axis
Which two lines form the angle of convexity?
NA - APg
What does the angle of convexity measure? Positive number reflect a class ___ relationship while negative number reflects a class ___ relationship.
Maxillary prognathism
Class II
Class III
describe Broadbent Registration and name which analysis it is used in
Intersection of Bolton- Nasion line and a perpendicular from Sella
Downs
what is the reference plane for the Steiner analysis?
SN
SNA, SNB, ANB are used in which analysis?
Steiner’s
In Steiner’s analysis, the growth pattern is evaluated with:
MPA: Go-Gn to SN
The norms for U1-NA and L1-NB are both ___mm. For Holdaway’s ratio, the ___ - NB should have the same value.
4
Pg
According to the S line, the lips should touch a line from ___ to middle of ______. The S line is part of the ________ analysis.
Pg
nose lower border
Steiner
The ___________ analysis was the first to offer specific guidelines for Tx planning
Steiner
The ___________ analysis was the first to emphasize interrelationship between individual measurements into a pattern
Steiner
The McNamara used a (well / ill) defined sample
well
The Tweed triangle is comprised of which 3 angles?
IMPA
FMIA
FMA
Ideal IMPA angle
90
Ideal FMA angle
25
High FMA angle is >___ and low FMA angle is
>30
<20
Ideal FMIA angle
65
In the Wits analysis a higher ANB correlation is noted due to the use of the ____________ occlusal plane is used as apposed to the ___________ occlusal plane
functional
bisected
The functional occlusal plane uses molars and __________ while the Down’s occlusal plane uses the molars and bisects __________
premolars
incisor OB
A negative Wits value indicates a lass ___ relationship while a positive Wits value indicates a class ___ relationship
III
II
What is the major limitation of the Wits analysis?
it does not distinguishing between dental and skeletal problems
Name the reliable landmarks for mandibular superimposition (4)
Third molar crypt
Inner cortical plate of symphysis
Mandibular canal
Inferior border
Name the reliable landmark for maxillary superimposition
Hard palate
Name the reliable landmarks for cranial base superimposition (3)
- Anterior clinoid **
- Cribriform plate
- Greater wing of sphenoid
What is a common stable reference for superimpositions?
Frankfort horizontal
Short Articulare to Pterygomaxillary fissure (Ar-PTM) demonstrates ____________ reflected in other analyses
retrognathia
anterior facial height is measured between which two points?
N-Me
posterior facial height is measured between which two points?
S - Go
ratio of AFH : PHF should be
60 : 40
upper facial height is measured between which two points? what is the average measurement?
N - ANS
60mm
lower facial height is measured between which two points? what is the average measurement?
ANS - Me
80mm
ratio of UFH : LFH should be
45 : 55
In a PA ceps, petrous portion of temporal bone lies in inferior__/__ of the orbit
⅓
In a PA ceps, the _______________ line is a radiopaque oblique line that passes through the orbits
temporal
In a PA ceps, the temporal line is formed by temporal surface of the:
greater wing of the sphenoid
Basion represents the most inferior-posterior point on the anterior margin of the __________ _________ on the ___________ bone
foramen magnum
occipital
According to ABO standards, the MP is formed from which two points?
constructed Go
Menton
According to the ABO discrepancy index, which cephalometric measurements are considered? (3)
IMPA
ANB
SN-MP
According to the ABO discrepancy index, which dental measurements are considered? (6)
- OB
- OJ
- Crowding
- Ant or Post crossbites
- Ant or Post open bites
- Alignment/occlusion
According to the ABO discrepancy index, what is the normal range of:
SN-MP?
27° - 37°
According to the ABO discrepancy index, what is the normal range of:
ANB
-2° - 6°
According to the ABO discrepancy index, what is the normal range of:
IMPA
< 99°
The ABO discrepancy index uses which measurement:
FMA or SN-MP?
SN-MP
According to the ABO discrepancy index, what is the normal value of:
SNA
82 deg
According to the ABO discrepancy index, what is the normal value of:
SNB
80 deg
According to the ABO discrepancy index, what is the normal value of:
SN-MP
33 deg
According to the ABO discrepancy index, what is the normal value of:
FMA
24 deg
According to the ABO discrepancy index, what is the normal value of:
U1-SN
103 deg
According to the ABO discrepancy index, what is the normal value of:
L1-MP (IMPA)
95 deg
According to the ABO discrepancy index, what is the normal value of:
UL - EP
-6mm
According to the ABO discrepancy index, what is the normal value of:
LL-EP
-2mm
According to the ABO superimposition standard, reliable sagittal cranial base landmarks include: (2)
anterior sella wall
greater wings of sphenoid
According to the ABO superimposition standard, reliable vertical cranial base landmarks include: (3)
ethmoidal crest
cribriform plate of ethmoid
walker point
According to the ABO superimposition standard, secondary cranial base landmarks include: (2)
planum sphenoidale
cerebral surface of orbital part of frontal bone
According to the ABO superimposition standard, primary maxillary landmarks include: (1)
anterior surface of zygoma btwn orbital rim and key ridge
According to the ABO superimposition standard, secondary maxillary landmarks include: (1)
maxillo-zygomatico-temporal sulci
According to the ABO superimposition standard, primary mandibular landmarks include: (3)
anterior contour of chin below Pg
inner contour of cortical plate at lower border
IAN
According to the ABO superimposition standard, primary mandibular landmarks include: (1)
Mineralized tooth germ
According to ABO discrepancy index, a loss of ___+ points is a fail. It is desirable to have
30
20
What parameter is not used to evaluate Tx according to the ABO DI?
OB
According to the ABO discrepancy index, what is the normal angular difference between: FH and SN
7 deg
Name the components of the ABO CR index for evaluating treatment outcomes (8)
- JAMIROCC: Overjet
- root angulation
- marginal ridge
- inclination
- rotations
- occlusion
- contact incisor position
- contact occlusion
If you use Machine Porion instead of anatomic porion, you can expect FMA and Y-axis to ( increase / decrease )
increase
Cephalometric analysis was first done by:
Tweed
With age, we can expect the facial angle to ( increase / decrease ) and the MP to ( increase / decrease )
increase
decrease
When considering esthetic lines, the E line is measured from _________ to ___________ and was used in the _________ analysis .
Tip of nose → soft tissue Pg
Ricketts
When considering esthetic lines, the H line is measured as a tangent from _________ to ___________ and was used in the _________ analysis .
ST Pog → upper lip
Holdaway
When considering esthetic lines, the B line is measured as a tangent from _________ to ___________ and was used in the _________ analysis .
St subnasale → ST Pog
Burstone
When considering esthetic lines, the S1 line is measured as a tangent from _________ to ___________ and was used in the _________ analysis .
Center of S shaped nares curvature → ST Pg
Steiner
