Panoramic Dental Radiography

Question 1

Possible indications

Answer 1

Examination of new dentate pxs
As aid for otho treatment
Prior to oral surgery
After facial trauma
Check for post-op healing
Investigation of TMJ 'dysfunction'

Question 2

New pxs

Answer 2

May be appropriate with heavily restored or neglected dentition where DPT can be used as means of identifying teeth requiring more detailed i.e. intra-oral, exam
Never ‘routine’

Question 3

Ortho

Answer 3

Routine screening is of limited benefit
Radiography indicated if clinical exam leabes reasonable suspicion as to presence of abnormality that may affect dento-facial development

Question 4

Perio assessment

Answer 4

Good px education

Question 5

Oral surgery

Answer 5

Useful for assessing 3rd molars prior to removal but sectional films should be considered for unilateral cases
May be useful where multiple extractions are planned
Useful for demonstrating full extent of large areas of bony pathology
Prior to apicectomy, root removal or enucleation of small cysts then intra-oral views are more appropriate

Question 6

Facial trauma

Answer 6

Excellent for assessing mandibular fractures

If clinical exam and history suggest presence of only dento-alveolar damage then intra-oral views more useful

Question 7

Post-op healing

Answer 7

May be indicated in some situations e.g. where there is possibility of further cyst formation elsewhere in jaws as in Gorlin’s syndrome
Sectional DPT may be more appropriate following local excision of lesion
Intra-orals clearly more appropriate following apicectomy

Question 8

TMJ disorders

Answer 8

Vast majority of pxs with TMJ ‘dysfunction’ do not have bony changes which will influence management, most have disc or muscular problems
Radiography not recommended for pxs with joint sounds in absence of other signs or symptoms
However, open-mouth DPT will give good overview of condyles if required

Question 9

Radiation dose and risk

Answer 9

Dose varies according to equipment used but is similar to that received during chest radiography
Approx equivalent to 1-5days additional background radiation
Risk of cancer per million exposures is approx 0.2-1.9

Question 10

Prep of px

Answer 10

Explain about machine movement to px, especially children
Ask px to remove glasses, neck-chains, earrings and dentures
Ensure that px places tongue against palate during exposure
Position px upright - not slumped

Question 11

Px positioning

Answer 11

Teeth/ jaws must be positioned so that they lie within image layer will be distorted
Structures positioned outside this layer will be distorted
Gross distortion may result in non-diagnostic film

Question 12

Common positioning errors

Answer 12

Px too far IN
Px too far OUT
Px 'CHIN UP' position
Px in 'chin down' position
Px's head ROTATED
Px SLUMPED not upright

Question 13

Px too far in

Answer 13

Anterior teeth will be blurred and narrow in appearance
Premolars will be overlapped
Cervical spine may be superimposed on rami

Question 14

Px too far out

Answer 14

Anterior teeth will be blurred and wide in appearance

Condyles may fall outside sides of film

Question 15

Px in ‘chin-up’ position

Answer 15

Roots of upper incisors will be blurred
Condyles may be lost at sides of film
Hard palate may be projected over upper root apices

Question 16

Px in ‘chin-down’ position

Answer 16

Lower incisor roots will be blurred
Hyoid bone may be projected over mandible
Occlusal plane will form characteristic ‘smile sign’

Question 17

Px’s head rotated

Answer 17

Teeth on one side of midline will have overla[[ing contacts and will be magnified relative to those on other side
Width of rami will also be different

Question 18

Px slumped, not upright

Answer 18

Results in opaque ghost image of cervical spine to be projected over midline of film

Question 19

Exposure factors

Answer 19

Px with large bone structure.. use slightly higher kV
Edentulous px.. next lower kVp/mA
Px with small bone structure - see above

Question 20

The four white lines

Answer 20

Hard palate
Floor of maxillary sinus
Posterior wall of maxillary sinus
Zygomatic buttress

Question 21

Air spaces

Answer 21

Between tongue and palate
In nasopharynx
In oropharynx
Outlining epiglottis

Question 22

Ghost images

Answer 22

Formed when object is located between x-ray source and centre of rotation
Appear on opposite side from real image
Always higher up and blurred

Question 23

Film viewing

Answer 23

Always use an appropriate viewing box
Make sure you know which side is which
Adopt systematic viewing technique
Look at whole film not just your area of interest - avoid 'tunnel vision'
Write report of your findings