Radiology 7 Flashcards
Why would you request a bitewing radiograph?
- To help detect caries or monitor caries progression.
- To assess periodontal status and also assess existing restorations.
What would you refer to for information on how you should assess whether or not a radiograph is necessary?
The chart in the Selection Criteria for Dental Radiography handbook available from the Faculty of General Dental Practice UK.
Horizontal bitewing
- The distal edge of the 4 to the mesial edge of the 8, unless the request states otherwise.
- Occasionally only one side may be requested. To cover the whole region of interest you should place the centre of the bite block on the centre of the 6. You are required to demonstrate the crowns of the teeth and one third of the roots.
Vertical bitewings
- As the long axis of the receptor is in the vertical plane, 2 radiographs are required to cover the desired teeth.
- Again you want to see from the 4 to the 8. You will demonstrate more of the root but you will still not see the apices.
When would you request vertical bitewing over horizontal?
If you are wishing to see more of the root and supporting bone.
Why could vertical bitewings be considered as disadvantageous to the patient in comparison to that of horizontal bitewings?
It involves irritating your patient 4 times compared to only twice with horizontal bitewings.
Vertical can also be more uncomfortable for the patient to tolerate due to the size of the receptor.
How would you position your bite block for a bitewing radiograph?
Place the block on the centre of the 6th molar.
- Film and object parallel
- Film close to object
- x-ray beam perpendicular to object and film
TIPS: always use a holder.
Two holder types
- Rigid plastic (holds film accurately, assists X-ray tube positioning, uncomfortable)
- Paper tab (comfortable, X-ray tube positioned by eye, inaccurate positioning)
When might horizontal overlap be difficult to avoid?
What would the effect of this clinically be?
Superimposition (horizontal overlap)
When is horizontal overlap unavoidable?
- Crowding or tilting of teeth
- Acceptable if less than half of enamel superimposed (however there is a chance you will miss early carious lesions)
What would the clinical impact of this be?
Vertical angulation
Two main problems with vertical angulation
You have projected the upper bone levels off the receptor and the resultant distortion of the teeth has caused separation of the cusps.
What is a key benefit of using a holder in terms of magnification?
It allows you to keep the source to object distance long, and the image receptor close to the object, thus reducing magnification.
Where does the orientation dot always go?
The orientation dot always goes to the palate on a bitewing not the crown as in peri-apicals.
Comment on this radiograph
Just OK
Comment on this radiograph
Repeat, no upper bone levels visible posterior to the 7.
Comment on this radiograph
Repeat, because 8 collimated off.
Comment on this radiograph
Repeat, receptor size selection incorrect, too small.
Comment on this radiograph
Repeat, vertical angulation causing elongation and lower bone level projected off.
Comment on this radiograph
Perfect
Comment on this radiograph
Repeat, collimation causing loss of lower bone levels
Comment on this radiograph
Good
Comment on this radiograph
Repeat, number 4 and receptor squint.
Comment on this radiograph
Good
Comment on this radiograph
Repeat, corner of film bent over so large area not exposed.
Comment on this radiograph
Repeat, too much overlap
Comment on this radiograph
Repeat, patient not biting on bite block
