Dental Technique - Cephalometry Flashcards
What is a cephalometry?
It is a standardised and reproducible radiography of the relationship of the soft tissues of the face to the facial bones and teeth
Why do we need cephalometry?
Prior to the maxillofacial surgery and orthodontic treatment assessment is necessary
During and after treatment further assessment/monitoring is necessary
That is why it is essential that all the images in the series are comparable
What are the features of the equipment?
It can be independent or part of unit with your function for orthopantomography
It has a fixed SID – 150 CM minimum to minimise magnification and geometric unsharpness
Movable nation support for in mobilisation of different head sizes – also involved in a filter position
Filter – to compensate for range in densities from facial soft tissues to facial bones
Explain the lateral projection – radiographic technique:
18x24cm Image receptor is placed on the holder of the machine - portrait
Earplugs covered with small disposable plastic bags – infection control
Patient stands erect inside unit – MSP parallel to image Receptor
 Machine height adjusted until earplugs can be inserted into external auditory meatus
Occlusal plane is horizontal
Needing support position against nation
White filter position to correspond with measurements on Asian support
Patient asked close back teeth for exposure
Fixed horizontal been – 90° to image Receptor
Fix centre in point – usually over earplugs
Collimation usually fixed to include soft tissue outline of forehead face/nose and mandible
What are the three radiographic base lines used in cephalometry imaging?
Anthropological baseline – runs from Laura border of orbit to Upper Border of EAM
Alatragal line – Runs from a lot of nose to tragus of ear
Occlusal plane – lies parallel to and about 4 cm distal to the alatragal line
What features of the cephalometry machine is seen on the image?
Head clamp
Centre of earplugs
Nasion support
What is the criteria for assessing the image quality?
Demonstration of soft tissue outline of face – including forehead nose lips chin and teeth/jaw
Whole of mandible and earplugs demonstrated plus measuring bar
Super imposition of earplugs – right/left facial structures indicating true lateral
Anthropological be fine horizontal
Back teeth in occlusion
Sharp image – demonstration of facial bones and soft tissues of face
What are some positioning errors of cephalometry?
Filter not applied - soft tissues of face too dark
Baseline not horizontal (chin too low) - denser soft tissues below chin in comparison with other soft tissues or face

Explain the PA projection:
Not done routinely
Assessment of facial a symmetry
Head support rotated 90°
Patient position as for PA mandible
OM base line parallel to the floor
Head and mobilise by inserting earplugs in the EAMs
Fixed horizontal been
Fix sending that through cervical spine at level of Rami
