Chapter 3/practice 6: Steiner’s Cephalometry Flashcards
What type of analysis is Steiner’s?
Linear and angular
Steiner’s analysis consists of?
Skeletal, dental, and soft tissue components
The skeletal component relates?
The maxilla and the mandible with each other and to the skull
The dental component relates?
The upper and lower incisor to each other and to the maxilla and mandible respectively
The soft tissue component understands?
The lower facial profile
Advantages of Steiner’s analysis?
- SN line: reference line
- easy to locate
- takes only 2 landmarks
- located in the mid sagital plane and moves minimally with head movement
- no bilateral points—> decreased risk of double images
- better than the Frankfurt plane at locating the porion and orbitale
Disadvantages of Steiner’s analysis?
- the values selected as “normal’ are a personal judgment (based on Hollywood actresses)
- no biological corrections of age, sex, and race such as in Rickett’s
- leaves areas with no analysis
- holdaway’s relationship is based on an uncertain phenomena of pogonion growth
What are the 10 cephalometric points in Steiner’s analysis?
- S point
- N point
- A point
- B point
- Pogonion
- Gonion
- Gnathion
- L point
- E point
- D point
S point:
The midpoint of the sella turcica
N point:
The most anterior point of the fronto-nasal suture
A point:
The deepest point of the concavity of the maxillary alveolar ridge
B point:
The deepest point of the concavity of the mandibular alveolar ridge
Pogonion point:
- definition
- abbreviation
- the most prominent point of the chin
- (Pg)
Gonion point:
- definition
- abbreviation
- the most inferior and posterior point of the mandibular angle
- (Go)
Gnathion point:
- definition
- abbreviation
- the most anterior and inferior point of the chin
- (Gn)
L point:
The point where the line perpendicular to Pg joins with SN line
E point:
The point where the line drawn from the most distal point of the mandibular condyle joins the SN line
D point:
The center of the mandibular symphysis
Which point is a more reliable reference of the position of the mandible (B or D)?
D
In what position does the skeletal analysis relate the maxilla and mandible to the skull and to each other?
Antero-posterior
SNA angle measures?
The anteroposterior postiton of the maxilla with regards to the cranial base
Mean value of SNA angle?
Higher=?
Lower=?
82° +/- 2°
- higher: maxillary protrusion
- lower: maxillary retrusion
A SNA value of 62° indicates?
Maxillary retrusion
A SNA value of 90° indicates?
Maxillary protrusion
SNB/SND angle measures?
The anteroposterior position of the mandible with regards to the cranial base
Mean value of SNB angle?
80° +/- 2°
Mean value of SND angle?
76° +/- 2°
A higher SNB/SND value indicates?
A lower SNB/SND value indicates?
Higher: mandibular prognathism
Lower: mandibular retrognathism
A SNB value of 70° indicates?
Mandibular retrognathism
A SNB value of 92° indicates?
Mandibular prognathism
A SND value of 80° indicates?
Mandibular prognathism
A SND value of 62° indicates?
Mandibular retrognathism
If SNA is 83° and SNB is 70° that indicates?
Mandibular retrognathism , class III mandibular etiology
If SNA is 70° and SNB is 70° that indicates?
A bimaxillary biretrognathism
If SNA is 62° and SND is 77° that indicates?
Maxillary retrusion, class III maxillary etiology
ANB angle measures?
The maxillo-mandibular relationship in the sagittal plane, gives a general idea of the sagittal or anteroposterior discrepancy of the maxilla to mandible apical bases
Mean value of ANB angle?
Higher=?
Lower=?
2° +/- 1°
Higher: class II
Lower: class III
Class II indicates that point A is forward to point B
SE distance represents?
The position of the posterior part of the mandible
Mean value of SE distance?
Higher=?
Lower=?
22mm +/- 2mm
Higher: condyle in backward position
Lower: condyle in advanced position
SL distance represents?
The effective size of the mandibular body
Mean value of SL distance?
Higher=?
Lower=?
51mm +/- 2mm
Higher: mandibular prognathism or counterclockwise rotation (brachy)
Lower: mandibular retrognathism or clockwise rotation (dolico)
Gonial angle measures?
The angle formed by the tangents to the lower edge of the mandible (Go-Gn) and the ascending ramus
Angle formed between the line (Go-Gn) and the ramus
Mean value of the Gonial angle?
Higher=?
Lower=?
125° +/- 5°
Higher: vertical pattern (dolico)
Lower: horizontal pattern (brachy)
Mandibular plane expresses?
The tendency of mandibular growth
Mean value of the mandibular plane?
Higher=?
Lower=?
32° +/- 2°
Higher: dolicofacial
Lower: brachyfacial
Occlusal plane represents?
A line connecting the vertical midpoint (between LS and LI of the incisors) and the mesial contact point between the first molars
Mean value of the occlusal plane?
Higher=?
Lower=?
14° +/- 2°
Higher: long face or vertically growing patients, skeletal open bite
Lower: horizontally growing patients, skeletal deep bite
XY axis measures?
The angle formed between SN and S-GN lines
Mean value of XY axis?
Higher=?
Lower=?
66° +/- 2°
Higher: vertical growth (dolico)
Lower: horizontal growth (brachy)
Dental analysis includes?
Linear measurements
Angular measurements
Ratio
NA distance measures?
Position of the incisor with respect to it’s apical base
The labial surface of the maxillary central incisors to NA line
Mean value of the NA distance?
Higher=?
Lower=?
4mm +/- 1mm
Higher: protruded
Lower: retruded
NA angle measures?
Incisors angulation with respect to their apical base
Long axis of the central incisor with NA line
Mean value of NA angle?
Higher=?
Lower=?
22° +/- 1°
Higher: proinclination
Lower: retroinclination
NB distance represents?
Position of the mandibular central incisor with respect to its apical base
Labial surface of the central incisor with NB line
Mean value of NB distance?
Higher=?
Lower=?
4mm +/- 1mm
Higher: protruded
Lower: retruded
NB angle measures?
Angulation of lower incisors with respect to its apical base
Long axis of central incisor with NB line
Mean value of NB?
Higher=?
Lower=?
25° +/- 2°
Higher: proinclination
Lower: retroinclination
Inter-incisive angle measures?
Angulation of the incisors with regards to each other
Intersection of the axial axis of both incisors
Mean value of inter-incisive angle?
Higher=?
Lower=?
131° +/- 4°
Higher: dental retroinclination
Lower: dental proinclination
Holdaway ratio measures?
The relative prominence of the mandibular incisors as compared to the size of the bony chin
Calculated as the ratio of the linear distance from the labial surface of the mandibular central incisors to the NB line over the distance of the chin to Pg-NB
Li-NB/Pg-NB
Holdaway ratio normal value?
2mm discrepancy is:
3mm discrepancy is:
4mm discrepancy is:
1:1 ratio
2mm: acceptable
3mm: less desirable
4mm: correction indicated
Soft tissue analysis: aesthetic analysis
S line (a line connecting the columella to soft tissue contour of the chin)
Normally, the lips should fall on this line, if they fall in front of the line? Behind the line?
In front of: proquelia
Behind: retroquelia