Intraoral Radiography 2 Flashcards
What are some important limitations to standard radiographic images?
Anatomical restrictions
Patient cooperation is not optimal
Patient with strong gag reflex
Patient cannot cope with the parallax technique
How is the bisecting angle technique done?
Image receptor is placed in contact with the patient’s tooth and soft tissues. There should be at least 2mm of the PSPP visible beyond the incisal or occlusal edge of the tooth.
The rays are aimed perpendicular to the imaginary bisecting angle between long axis of the tooth and the image receptor.
When is the bisecting angle technique not often used?
It is not the preferred technique due to being more likely to make mistakes which render the image not diagnostic because it is distorted in size and shape.
Interference of the image receptor holding and aiming device the patient cannot cope with the procedure.
It is easy to get wrong
How much demineralisation is neessary for it to be detectable on X-ray?
30 - 40%
How can amalgam affect dentine radioopacity?
Sn and Zn ions may diffuse into dentin and make it more radioopaque.
What PSPP plates are used for occlusal radiographs?
Size 4 PSPP
What information is provided by occlusal radiographs?
These radiographs provide a periapical view of canine to canine, provide information about the circumference of bony structures and eventual presence of supernumerary teeth, odontomas or foreign objects in the jaws.
In the mandible, the floor of the mouth can also be checked for radiopaque inclusions (eg sialolith, foreign object)
How is an upper standard occlusal radiograph taken?
Patient is positioned sitting up straight.
Size 4 PSPP placed on patient’s upper occlusal plane and patient bites down gently.
Position X-ray machine in with spacer cone pointing down at 65 degrees with central X-rays through the bridge of the nose.
verify if the projection of the spacer cone coincides with the circimference of the PSPP size 4
How is a 90 degree occlusal of the mandible taken?
Patient positioned upright with PSPP size 4 on lower occlusal plane.
Patient closes mouth gently and tilts head backwards so that occlusal plane is perpendicular to the floor.
Aim X-ray perpendicular to the occlusal plane onto the PSPP size 4 plate.
*This can also be done with the patient lying down with chair back
How is a 45 degree occlusal of the mandible taken?
Patient is positioned upright in the dental chair and a size 4 PSPP plate is placed on the lower occlusal plane and patient closes mouth with teeth touching the plate gently.
X-ray is pointed upwards at 45 degrees through the tip of the chin.
This can also be done with a size 2 PSPP
What are the indications for using occlusal radiographs?
Assess expansion of the bone in buccal and lingual dimension
Assess the position of impacted teeth of foreign objects
Assess sialoliths in the floor of the mouth
45 degrees lower occlusal and 65 degrees upper occlusal can be a good alternative to periapical radiographs
Mandibular fractures and no 3D available
When is oblique occlusal radiography used?
it is an alternative for when parallel and bisecting angle imaging both don’t work and we are trying to image the posterior teeth.
What are the important limitations to oblique occlusal radiography?
This technique is not easy to perform.
Geometric mistakes are common with this technique.
How are oblique occlusal radiographs taken?
Maxilla:
Patient is positioned upright in dental chair so that occlusal plane is parallel to the floor.
Size 2 or size 4 PSPP on the patient’s occlusal plane, make sure it can be seen buccally from the teeths’ crowns
Ask patient to gently close teeth on the plate
Position X-ray machine downwards at a 65 - 55 degree angle with central X-ray beam aiming through the apex of the tooth.
Mandible:
Head faces sideways, PSPP on occlusal plane and X-rays aimed upwards at 25 - 30 degree angle.
What are the indications for using oblique occlusal radiographs?
Alternative to periapical radiographs
Gagging patients might benefit
Young paediatric patients might benefit
Special needs patients might benefit
