Panoramic Dental Radiography Flashcards
Possible indications
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'
New pxs
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’
Ortho
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
Perio assessment
Good px education
Oral surgery
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
Facial trauma
Excellent for assessing mandibular fractures
If clinical exam and history suggest presence of only dento-alveolar damage then intra-oral views more useful
Post-op healing
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
TMJ disorders
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
Radiation dose and risk
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
Prep of px
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
Px positioning
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
Common positioning errors
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
Px too far in
Anterior teeth will be blurred and narrow in appearance
Premolars will be overlapped
Cervical spine may be superimposed on rami
Px too far out
Anterior teeth will be blurred and wide in appearance
Condyles may fall outside sides of film
Px in ‘chin-up’ position
Roots of upper incisors will be blurred
Condyles may be lost at sides of film
Hard palate may be projected over upper root apices
Px in ‘chin-down’ position
Lower incisor roots will be blurred
Hyoid bone may be projected over mandible
Occlusal plane will form characteristic ‘smile sign’
Px’s head rotated
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
Px slumped, not upright
Results in opaque ghost image of cervical spine to be projected over midline of film
Exposure factors
Px with large bone structure.. use slightly higher kV
Edentulous px.. next lower kVp/mA
Px with small bone structure - see above
The four white lines
Hard palate
Floor of maxillary sinus
Posterior wall of maxillary sinus
Zygomatic buttress
Air spaces
Between tongue and palate
In nasopharynx
In oropharynx
Outlining epiglottis
Ghost images
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
Film viewing
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
