Techniques m3 Flashcards
What are the Intra-oral x-rays?
- peri-apical
- bitewing - horizontal and vertical
- occlusal - maxilla and mandible
What are Extra-oral x-rays?
- dental panoramic tomogram -DPT
- lateral cephalogram
- postero-anterior mandible
- lateral oblique mandible
- occipito-mental views of facial bones
Why would you use a Peri-apical?
- detect apical inflammation/infection to include cystic changes
- assess periodontal problems
- trauma-fractures to tooth and/or surrounding bone
- tooth morphology pre extraction
- presence/position of unerupted teeth
- endodontics
- pre/post apical surgery
- evaluation of implants
what are the 2 tachniques to 2 teachiques used to take a radiograph?
- Paralleling technique
- Bisected angle technique
What is the difference between Paralleling technique and Bisected angle technique?
Paralleling
- Uses holders to facilitate positioning
- Receptor parallel to tooth
- Accurate/ reproducible image
Bisected angle
- Can be done without a holder
- Operator dependent
- Not reproducible
Why is Paralleling the technique of choice?
- Uses holders to facilitate positioning
- Allows accurate geometry of image
- Receptor parallel to tooth
- X-ray beam perpendicular to tooth/receptor
- Minimises magnification
- Accurate/reproducible image
- Holders are bulky and may not be tolerated by patient. Can reduce dose to patient by reducing repeats and does not expose patients fingers (see bisected angle)
what are holders made up of?
- A bite-block - retains the receptor
- an indicator arm/rod - fits into the bite-block
- an aiming ring-slides onto the arm to establish alignment of collimator with receptor
What are the 2 types of receptors?
Film and Digital
What is the receptor-tooth relationship?
- The vertical plane of the film should be positioned so that it is parallel to the long axis of the tooth/teeth.
- The horizontal plane of the film must be parallel to the dental arch under examination
How should X-ray tube position for vertical angulation be set up and what can happen if it is not set up right?
xray beam should be at right angles to the tooth/receptor
How should X-ray tube position for horizontal angulation be set up and what can happen if it is not set up right?
Xray beam 90o to Receptor
What are thinga that affect image size?
- X-ray source (focal spot) to receptor distance
- Object (tooth) to receptor distance
What are some barriers to good positioning?
- Mouth size
- Gag reflex
- Film size
- Digital sensor size and shape
What are the 4 most common film/PSP receptor sizes?
1,2,3,4
What are the problems in each of these xrays?
What Film size would you use for Periapicals?
Adult
Anterior – “0”, “1” “2” – bisecting angle
Posterior – “2” only
Child
Anterior – “0”
Posterior:
- Deciduous – “0”
- Permanent – “2”
What Film size would you use for Bitewing - vertical or horizontal?
Adult – “2” only
Child – over 10 – “2”
Child – under 10 – “0” or “1”
For clinical knowledge where is the “controlled area”?
