Cephlometric Flashcards
What is Cephlometric ?
- It is reproducible radiographs of lateral Skull to assess facial, dental and skeletal relationship in vertical and anterior posterior dimensions.
How much magnification and distance?
10% with 6ft tube- film distance
How can you tell age by ceph?
- Spine 1,2,3 changes shape to more rectangular
What information Ceph give you?
- Dimension and relationship of bones - Skeletal pattern
- Position and angulation of teeth
- Size and shape of soft tissue
Why do we use Ceph for?
- Diagnose
- Treatment planing
- research
- Monitor progress
Problem with accuracy of Cephs?
- Bad technique when taking radiographs
- Lips tensed together or apart
- Heads not straight
- Machine set up wrong
- Patient is not biting together
- Poor identification of points
- Mistakes in measurement
What are the points of Cephmetric points, planes?
- Point A.
- Point B.
- Sella S
- Porion Po
- Nasion N
- Orbital Or
- Gonion Go
- Menton Me
- Pogonion Pog
- Gnathion Gn
- SN lines
- SNA
- SNB
- ANB
Frankfort plane?
Porion to orbital Po - Or
Mandibular Plane
Go Gonion - Me Menton
Maxilllary plane
ANS - PNS
ANB angle for average?
3 degree +/- 2
SNA angle?
- 81 degree +/-3
SNB angle
- 78 degree +/- 3
Maxillary and mandibular plane angle ? MMPA
- 27 degree +/- 5
Upper incisors to Maxillary plane angle? UI MxPn
- 109 +/- 6
Lower Incisor to Mandibular plane? LI MdPn
- 93 degrees +/- 6
Interincisal angle ?
135 degree +/- 10
Lower incisors- mandibular plane angle LI Apo
- 1mm +/-2mm
TFH - Total facial height
-119mm
UAFH - Upper anterior face height
- 54mm
LAFH- Lower anterior face height
- 65mm 55%
Nasiolabial angle NLA
-100 degree
E- line
Upper lip - 4mm
Lower lip - 2mm
ANB - Skeletal class
Class I - 2-4 degree
Class II- more than 4 degrees
Class III- less than 2 degrees
How do you take Cephlometric?
- It is taken from distance of 1.5m with head at the right angle to the xray beam at distance of 30cm.
-Magnification 10% 6 ft distance tube and film - Two ear rods which are placed in external auditory meatus.
- Saggital plane should be parallel to xray film
- Teeth in centre occlusion
- Frankfort plane horizontal.
Define A point?
- the point of deepest concavity anteriorly on maxillary alveolus
Define B point?
- The point of deepest concavity anteriorly on mandibular symphysis
Define S sella?
- The midpoint of Sella Turcica ( pituitary fossa)
Define N Nasion?
- The most anterior point on fronto- nasal suture
SN line define?
- The plane demonstrated by line through the nasion and sella
Which angle represents the relative anterior- posterior position of maxilla to cranial base?
- SNA
The angle represents the relative anterior - posterior position of the mandible to cranial base?
- SNB
Which angle represents the relative anterior posterior position of maxilla to mandible and can used to determine skeletal class?
- ANB
What is Eastman correction?
- it’s correction potential inaccuracy in position of Nasion.
- If SNA is greater than 81 degrees , 0.5 per degree should be subtracted from ANB
- If SNA degree less than 81 degrees, 0.5 per degree should be added to ANB
The correction of for ANB can only be applied if SN- maxillary plane within normal range of 8 +/- 3 degrees
-E.g SNA is 85 degree - average 81= 4
6 - (0.5*4) =
6-2 = 4 degree
Wits Appraisal ?
- To avoid Error associated with discrepancies of position of cranial base within skull
- Useful for assessing mandible and maxillary AP relationship seperate from skeletal basses.
- Draw perpendicular lines from A point or B point the occlusal plane
- BO+1mm ahead of AO (Male)
- BO = AO
