8 - Basic Cephalometrics Flashcards
what is the assessment of craniofacial dimensions utilizing standardized landmarks
cepahlometrics
what is drawn using cephalometric landmarks
landmark lines, angles, and planes
T/F: Profile convexity or concavity results from a disproportion in the size of the jaws
TRUE
can you determine which jaw is causing facial disharmony just by determining facial profile?
NO!
Convex profile indicates Class ___ jaw relationship which can result from a maxilla that projects to far or a mandible too far back
Class II
Concave profile indicates Class ___ jaw relationship which can result from a maxilla that is too far back or a mandible that protrudes too far forward
Class III
purpose of cephalometrics
- Study craniofacial growth
- Diagnosis
- Planning orthodontic treatment
- Evaluation of orthodontic treatment during or after case completion
X-ray tube should be __ inches from mid-sagittal plane of patient
60 inches
Film/sensor should be ___ inches from mid-sagittal plane of patient
7.5 inches
how to do traditional lateral ceph tracing
radiographic film, light box, and acetate paper
how to do contemporary lateral ceph tracing
Digital radiographic image captured, and software systems used to plot points, planes, measure angles etc.
what is the midpoint of the hypophyseal fossa (ovoid area of the spheroid bone that contains the pituitary gland)
Sella turcica
what is the external junction of the nasofrontal suture in the median plane
nasion
what is the most inferior point on the external border of the orbit
orbitale
what is the most superior point on the articular head of the condyle
condylion
what is the most anterior projection of the anterior nasal spine of the maxilla in the median plane
anterior nasal spine
what is the deepest point of the curvature of the anterior maxilla between the anterior nasal spine and the alveolar crest
subspinale
what is the deepest point of the curvature of the anterior maxilla between the anterior nasal spine and the alveolar crest
supramentale
what is the most anterior point on the midsagittal mandibular symphysis
pagonion
what is the most inferior point of the mandibular symphysis
menton
what is constructed point that is formed by the intersection of the facial and mandibular planes
gnathion
what is the constructed point that is formed by the intersection of the lines of tangent to the posterior margin of the ascending ramus and the mandibular plane
gonion
what is the most superior point of the external auditory meatus (top of metal ring of left ear cephalostat rod)
porion
what is the most inferior posterior point on the occipital bone that corresponds to the anterior margin of foramen magnum
basion
what is the tip of the posterior spine of the palatine bone
posterior nasal spine
A
sella turcica
B
Porion
C
condylion
F
orbitale
G
basion
J
posterior nasal spine
K
anterior nasal spine
L
A point: subspinale
M
gonion
N
B point: supramentale
O
pagnion
P
gnathion
Q
menton
what is plane constructed by line from porion (Po) to orbitale (O) (basic horizontal plane of the head)
frankfort horizontal
what is plane constructed by line from nasion (N) to pagonion (Pg)
facial plane
what represents the anterior-posterior extent of the anterior cranial base
sella-nasion plane
what is line extending through the anterior and posterior nasal spine (ANS-PNS)
palatal plane
what is line separating the maxillary and mandibular molars and extending through the contact of the most anterior maxillary and mandibular incisors
occlusal plane
what is line of tangent along the inferior border of the mandible
mandibular plane
A
SN
B
FH
C
PP
D
OP
E
MP
what is angle between sella-nasion line and nasion–A point line
SNA
what is angle between sella-nasion line and nasion-B point line
SNB
what is the difference between SNA and SNB angles
ANB
what is angle formed between the nasion–pagonion line and the Frankfort horizontal plane
facial plane angle
what is angle formed between the mandibular plane – and the Frankfort horizontal plane
mandibular plane angle (FMA)
what is angle between sella-nasion line and incisor long axis
maxillary incisor angulation
what is horizontal distance from facial surface of maxillary central incisor to the nasion-A point line
maxillary incisor AP position
what is angle between mandibular plane and long axis of inciso
mandibular incisor angulation
horizontal distance from tip of mandibular incisor to the A point- Pagonion line
mandibular incisor AP position
what is angle between sella-nasion line and nasion–A point line
SNA
clinical norm and clinical deviation of SNA
Clinical norm: approximately 82˚
Clinical deviation 2˚
what does SNA interpret
Establishes horizontal location of the maxilla relative to the cranial base. High numbers may indicate maxillary prognathism. Lower numbers may indicate maxillary retrognathism
Other variables influence interpretation such as age and ethnicity
angle between sella-nasion line and nasion-B point line
SNB
clinical norm and deviation of SNB
Clinical norm: approximately 80˚
Clinical deviation 2˚
how to interpret SNB
Establishes horizontal location of the mandible relative to the cranial base. High numbers may indicate mandibular prognathism. Lower numbers may indicate mandibular retrognathism
Other variables influence interpretation such as age and ethnicity
what is the difference between SNA and SNB angles
ANB
clinical norm and deviation of ANB
Clinical norm: approximately 2˚
Clinical deviation 2˚
how to interpret ANB
Indicates the horizontal relationship between the maxilla and mandible. Positive values greater than 4˚ is indicative of a skeletal Class II pattern. Values less than 0˚ indicative of a skeletal Class III pattern
Other variables influence interpretation such as age and ethnicity
what is angle formed between the nasion – pagonion line and the Frankfort horizontal plane
facial plane angle
how to interpret facial plane angle
locates the horizontal position of the chin and determines if the skeletal profile is retrognathic or prognathic
Other variables influence interpretation such as age and ethnicity
clinical norm and deviation and type of mandible angles of facial plane angle
Clinical norm: approximately 89˚
Clinical deviation 3˚
Greater than 90˚ indicates prognathic mandible
Less than 90˚ indicates retrognathic mandible
what is angle formed between the mandibular plane – and the Frankfort horizontal plane
mandibular plane angle
clinical norm and deviation and type of groth pattern for mandibular plane angle
Clinical norm: approximately 26’
Clinical deviation 4°
Greater than 31° indicates dolichofacial (long face) growth pattern
Less than 21® indicates brachyfacial (short face) growth pattern
what is angle between sella-nasion line and incisor long
maxillary incisor angulation
clinical norm and deviation of maxillary incisor angulation
Clinical norm: approximately 102
Clinical deviation 3°
how to interpret maxillary incisor angulation
relates the upper incisor angulation to the upper and middle face. Values greater than 105˚ indicate incisor protrusion, values less than 99˚ indicate incisor retrusion
what is horizontal distance from facial surface of maxillary central incisor to the nasion-A point line
maxillary incisor AP position
clinical norm and deviation of max incisor AP position
Clinical norm: approximately 4 mm
Clinical deviation 2mm
how to interpret maxillary insicor AP position
Interpretation: Indicates horizontal position of the maxillary
incisors. Values greater than 6 mm indicate anterior dental
protrusion, values less than 1mm indicate dental retrusion
Other variables influence interpretation such as age
and
ethnicity
what is angle between mandibular plane and long axis of incisor
mandibular incisor angulation
clinical norm and deviation of mandibular incisor angulation
Clinical norm: approximately 90˚ Clinical deviation 4˚
how to interpret mandibular incisor angulation
Gives an evaluation of the angular position of the incisor to the mandibular basal bone. Values greater than 94˚ indicate incisor protrusion, values less than 86˚ indicate incisor retrusion
what is the horizontal distance from tip of mandibular incisor to the A point-Pagonion line
mandibular incisor AP position
clinical norm and deviation of mandibular incisor AP position
Clinical norm: approximately 2 mm
Clinical deviation 2.3mm
interpretation of mandibular incisor AP position
Defines the anterior-posterior position of the mandibular dental unit. Values greater than 4.5 mm indicate mandibular dental protrusion, values less than 0mm indicate mandibular dental retrusion
Other variables influence interpretation such as age and ethnicity
what is The angle formed by the intersection of the lines of tangent to the columella of the nose and the upper lip
nasolabial angle
what does the nasolabial angle interpret
Provides an assessment of the nose to upper lip relationship
clinical norm and deviations of nasolabial angle
Clinical norm: approximately 90-110˚ Greater than 114˚ may indicate upper lip retrusion Less than 96˚ may be associated with dental protrusion
what is line connecting the tip of the nose and the most anterior point on the soft-tissue chin
aesthetic (E-plane)
what is the horizontal distance between the lower lip and the aesthetic plane
lip protrusion
interpretation of aesthetic plane and lip protrusion
Indicates soft-tissue balance between the lips and profile
clinical norm and deviation of aethetic plane and lip protrusion
Clinical norm: approximately -2mm @ 8.5 years old, -5 mm @ adulthood
Clinical deviation 2 mm