Cephalometrics Flashcards
Define the Jugal Process
intersection between the maxillary tuberosity outline and the zygomatic buttress
A Large anterior cranial base (S-N) indicates what?
Class II skeletal
A large posterior cranial base (S-Ba) indicates what?
Class II skeletal
A large cranial base angle (N-S-Ba) indicates what?
Class II skeletal
A small or short posterior cranial base (S-Ba) indicates what?
Class III skeletal
By what growth process does the cranial base grow?
Endochondral growth
What are the radiopaque lines that pass through the orbits in a PA ceph
Greater and lesser wings of Sphenoid
What is the oblique line on the orbit (though appears nearly horizontal in lower 1/3 of orbit) in a PA ceph
the Temporal line (petrous part of temporal bone)
What is the most common and stable reference line
Frankfort Horizontal
What is the Holdaway Ratio
1:1 ratio for distance between L1 to N-B and Pg to N-B
What is the Holdaway Ratio used for?
A measurement to evaluate the relative prominence of the mandibular incisors, as compared to the size of the bony chin
What is indicated by a short Articulare - Pterygomaxillary Fisure (Ar-PTM) ?
Maxillary retrognathia
Basion is found on what bone of the skull
Occipital bone
What landmarks define the Anterior Facial Height (AFH): Posterior Facial Height (PFH) ratio?
AFH –> N-Me
PFH –> S-Go
Ratio: AFH/PFH
What is the ideal anterior facial height : posterior facial height ratio?
60:40 (AFH/PFH)
What landmarks define the Upper Facial height (UFH) : Lower Facial height (LFH) ratio?
UFH –> N-ANS
LFH –> ANS-Me
What is the ideal upper facial height : lower facial height ratio?
45:55 (UFH/LFH)
Define the Zygomatic Arch (ZA) on a PA ceph
The center point of the zygomatic arch
“Not the Lateral point) = Zygion
Define the Bolton Point
the highest point in the concavity posterior of occipital condyle
(The occipital condyle articulates with the superior facets of the atlas (C1) vertebra)
Define Basion
The median point of the anterior margin of the foramen magnum
Define Opisthion
most posterior point on foramen magnum (opisthios = posterior)
Define the Facial Plane
N - Pg
What is the Bolton (Broadbent) triangle
Bolton - S - N
Describes growth change between the cranial base and the face
Define the Facial Axis
PTM - Gnathion
Define the Facial Axis angle
Angle formed between a line from N-Ba and PTM-Gn (Facial axis)
Should be 90 degrees
Define the Facial Angle
Angle between FH & N-Pg (88 degrees)
**increases from 8-18 yo
What anatomical landmark is noted by PT point
lower lip of Foramen rotundum
Describe the best use of Cephalometrics
to determine dental pattern related to skeletal pattern
What is the most difficult cephalometric point to identify
A point
Define Prosthion
most inferior anterior point of maxillary alveolus between the maxillary incisors
