lateral cephalometrics Flashcards
Why is cephalometrics used in diagnosis and treatment planning?
- Allows assessment of AP and vertical skeletal patterns.
- Shows the incisor positions and angular ion.
- Monitors the progress of treatment.
What are the 10 cephalometric points?
(SNABO and Po ANS PNS Go Me)
S - sella
N - naison
A - A point
B - B point
O - orbitale
Po - porion
ANS - anterior nasal spine
PNS - posterior nasal spine
Go - gonion
Me - menton
Where is the sella cephalometric point?
The midpoint of sella turcica (depression in the sphenoid bone containing the pituitary gland).
Where is the Naison cephalometric point located?
In the most anterior point on the frontonasal suture.
What is the A point in cephalometrics?
The point of deepest concavity anteriorly on the maxillary alveolus.
Where is B point in cephalometrics?
The point of deepest concavity anteriorly on the mandibular symphysis.
Where is Orbitale located?
The most inferior, anterior point located on the infraorbital rim.
Where is the porion located?
The uppermost outermost point on the bony external auditory meatus.
Where is the ANS?
The tip of the posterior nasal spine.
Where is the PNS?
The tip of the posterior nasal spine.
Where is Gonion?
The most posterior inferior point on the angle of the symphysis.
Where is menton?
The most inferior point on the mandibular symphysis.
Which 2 points are connected by the SN line?
Midpoint of sella turcica and naison.
Is taken to resemble the cranial base.
Where is the Frankfort Plane?
The line joining porion and orbitale.
(runs from the tragus to the bottom of the orbit)
Which 2 points are joined by the mandibular plane?
Gonion and Menton
Which 2 points are joined by the Maxillary Plane?
The ANS and PNS
What is the Functional Occlusal Plane?
The line drawn between cusp tips of permanent molars and premolars.
What does the SNA represent?
The relative A-P position of the maxilla to the cranial base.
What does the SNB angle represent?
The relative A-P position of the mandible to the cranial base.
What does the ANB angle represent?
The relative A-P position of the maxilla to the mandible.
What can the ANB angle be used to determine?
Skeletal Class
If the ANB angle is 2-4º, which skeletal class would this correspond to?
Class I
If the ANB angle is greater than 4º, which skeletal class would this correspond to?
Class II
If the ANB angle is less than 2º, which skeletal class would this correspond to?
Class III
Which 2 angles can a variation in position N affect?
SNA and SNB
What assumption does the Eastman Analysis make?
That the cranial base (SN) is a reliable basis for comparison.
Describe the Upper Incisors to Maxillary Plane Angle
The angle between the maxillary plane and axis of maxillary incisors.
Describe the Lower Incisor to Mandibular Plane Angle.
The angle between the mandibular plane and mandibular incisors.
What are both the UI/Max and LI/Mand angles used to determine?
Incisal position and if they are average inclination, proclined or retroclined.
What is Wits Analysis?
Compares the maxilla and mandible with the functional occlusal plane.
What is the functional occlusal plane?
The line drawn between the cusp tips of molars and premolars.
