Occlusal Radiology Flashcards
What are the diff types of occlusal radiographs you get?
- Oblique
- true (cross sectional)
- lower only
What types of sensors are used in GDH
phosphor plates
What are the indications for an oblique occlusal? (4)
- for a periapical type assessment where periapicals aren’t possible (e.g. trismus)
- Pathology too large to be seen on a single periapical (maybe CBCT now)
- Trauma (fractures to teeth and alveolus)
- Localisation using parallac (+ panoramic, other occlusal or periapical)
Describe what the head position is when taking an oblique occlusal and what lines you check for this?
Tilt the head slightly forward (supported by head rest) Want the ala-tragus line and the occlusal plane to be parallel to the floor ( NOTE: patient is seated
Where is the occlusal plane for the mandible?
From corner of the mouth the the tragus
What is the head position for mandibular oblique occlusals?
Occlusal plane (corner of mouth to tragus) is parallel with the floor head will be tilted back
What side of the phosphor plate is the active side?
The blue side/side without writing
How is the phosphor plate placed into the plastic cover?
So the side with writing can be seen (clear side) and dot in the corner is inserted first (so will be at bottom)
What is used to protect the x-ray packet/phosphor plates from damage?
Hinged carboard or plastic
How is the x-ray packet placed into the patients mouth?
With the black side facing the x-ray source The dot is outside the patients mouth
What will the patient be asked to do in order to keep the x-ray packet in place?
Bite gently (watch to ensure no chewing action)
What should the horizontal angle to the teeth being examined be?
90 degrees
What is a centring point?
Point where imaginary central ray is going to go in
Where should the centring point for an oblique occlusal (maxilla) be?
1cm above the ala-tragus line
How should the collimator of the x-ray machine be positioned to ensure the centring point is 1cm above the ala-tragus line?
Just above the bride of the nose
Centring point for mandibular oblique occlusal?
Through the lower border of the mandible
Centring point for a maxillary periapical?
On ala-tragus line
Centring point for a mandibular periapical?
1cm above lower border of mandible
What should the mid-sagittal line and the inter-papillary line be like when the patient is positioned correctly for maxillary oblique occlusals?
mid-sagittal = perpendicular to the floor inter-papillary = parallel to the floor
The x-ray tube should have an approx vertical angulation of what?
60 degrees
How should the vertical angulation change for proclined vs retroclined teeth?
Proclined = increase Retroclined = decrease
Describe a true/cross-sectional occlusal radiograph?
-an occlusal size image receptor or periapical size -plan view when beam is through long-axis of a tooth
What are the indications for a mandibular true occlusal?
• Detection of submandibular duct calculi • For assessment of bucco-lingual position of unerupted teeth ** • Evaluation of pathological bucco lingual expansion ** • Horizontal displacement of fractures ** ** = cone beam CT may be used nowadays if available
How is the image receptor placed? (true occlusal)
-Transverse in occlusal plane or lengthwise over region of interest
How is head placed and how is x-ray beam directed? (true occlusal)
-head tipped back as far as comfortable -x-ray beam directed at 90 degrees to image receptor in midline OR through region of interest
