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Chapter 42 - Extraoral Imaging DA
Terms in this set (37)
Outside of the mouth
• Useful for evaluating large areas but have never been recommended for detection of subtle changes such as dental caries or early periodontal change.
Images allows dentist to detect carries, view entire dentition, and related structures in one film
Types of panoramic imaging:
Film based imaging and direct digital imaging
What is the main difference between film based and direct digital imaging?
Known as the image layer
What shape is the focal trough?
Jaw has to be positioned in this area, if not distortion will be the result:
The patients lips must be ___________ on the bite-block during exposure of a panoramic film If not, a _____________ shadow will appear on the anterior teeth.
Tongue should be in contact with the __________ during exposure. If not, a dark ___________ shadow will appear on the apices of the maxillary teeth.
Detail in the __________ __________ region will be lost.
A ___________ smile line will be apparent on the radiograph.
Maxillary incisor, reverse
Position the patient so that the _____________ ____________ is parallel to the floor.
Panoramic Patient Positioning Error
Condyle will not appear
Mandibular incisors will appear blurred
Exaggerated smile line
Frankfort plane should be parallel to the floor
Chin too Low
If anterior teeth are not positioned in the groove of the bite-block and they are too far forward, how do the teeth appear?
Skinny and out of focus
How should the patient be sitting for a panoramic image?
If the patient is not sitting up straight what will appear on the film as a radiopacity in the center of the film, obscuring the diagnostic information?
Where should the grid be placed?
Between the patients head and the film
Device used to reduce the amount of scattered radiation that reaches a patient during exposure.
Decreases film fog and increases contrast of the radiographic image.
Scattered radiation is absorbed by _____________________________ and does not reach the surface of the film (reducing film fog)
The lead strips
Cone Beam Computed Tomography
Images can be sent over the internet and allows for collaboration and consultation
Used primarily for diagnosis of lesions and planning implant cases.
Helpful with extractions of impacted teeth and location of mandibular nerve before surgery.
What is Cone Beam Computed Tomography?
Digital images that can be manipulated, adjusted, and colorized on the computer.
Used in oral surgery and orthodontics
Common x-ray of the bone of the face, skull, and soft tissue profile.
Main components of a panoramic unit:
Tubehead, head positioner, exposure controls
Has a filament that produces electrons and a target that produces radiographs.
Where does the tubehead and film sensor rotate?
Behind the patients head at the same time
Used to alight the patients teeth as accurately as possible
Consists of chin rest, notched bite block, forehead rest, and lateral head supports
Allows the mA and kV settings to be adjusted to accommodate patients of different sizes.
Entire maxilla and mandible can be viewed on one image
Exposing is quick and easy
Most patients prefer because it is more comfortable
Patient receives less radiation as compared to FMX
Advantages of Panoramic Imaging
Panoramic Quality Depends on:
Size of jaws, How closely jaw conforms to focal trough, Patieint jaw positioned within focal trough
Ghost Images as a result of metallic or radio dense objects
Glasses, earrings, necklaces, piercings, jewelry, RPD, hearing aids, etc.
Image left on x-ray film will look similar to object but blurry, larger, and on the opposite side of the film
Common errors in panoramic images
If incorrectly placed, __________________________ with a thyroid collar will result in a radiopaque cone shaped artifact on film.
The lead apron
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