basic cephalometrics
TRANSCRIPT
Cephalometrics is a technique employing oriented radiographs for the purpose of making head measurements.
Purpose of Cephalometrics
• Study craniofacial growth• Diagnosis• Planning orthodontic treatment• Evaluation of treated cases
15"60"
Source Plane
X-ray Source
Patient in Head Positioning Device
Mid-saggital Plane
Film Plane
X-ray Film in Cassette
Cephalostat
White Black Israeli Chinese Japanese
SNA 82 85 82 82 81
SNB 80 81 78 79 77
ANB 2 4 4 3 4
U1-NA 4 mm, 22 7 mm, 23 5 mm, 24 5 mm, 24 6 mm, 24
L1-NB 4 mm, 25 10 mm, 34 6 mm, 29 6 mm, 27 8 mm, 31
U1-L1 131 119 124 126 120
GoGn-SN 32 32 35 32 34
L1-MnPl 93 100 93 93 96
L1-FH 62 51 57 57 57
Y axis 61 63 61 61 62
from Proffit,Contemporary Orthodontics, 1992
Cephalometric Values for Selected Groups
What Are We Trying to Accomplish?
• Find out skeletal classification– anteroposterior– vertical
• Find out angulation of incisors• Consider soft tissue
– facial profile– airway considerations
What Are We Trying to Accomplish? (In other words)
• Is the patient Class I, II, III skeletal?• Does the patient have a skeletal open bite
growth pattern, or a deep bite growth pattern, or a normal growth pattern?
• Are the maxillary/mandibular incisors proclined, retroclined or normal?
• Is the facial profile protrusive, retrusive, or straight; can the patient breathe normally?
Sella
Porion
Gonion PNS
Menton
Gnathion
Pogonion
B PointA PointANS
Orbitale
Nasion
Articulare
Standard Cephalometric Landmarks
Children with airway obstruction, whencompared to normal controls, show:
Nasorespiratory Considerations
• Increased total and lower face heights• More retrognathic mandibles• Steeper (increased) mandibular plane
angles• Spontaneous improvement after
reestablishment of normal respiration