Radiography Flashcards
Types of intraoral radiographic examinations
Periapical
Interproximal
Occlusal
Purpose, receptor and technique used for PA
Purpose: to examine the entire tooth (crown and root) and supporting bone
Receptor: pa receptor
Technique: 2 methods.. paralleling and bisecting
Purpose, receptor and technique of interproximal examination
(BW) purpose: to examine crowns of maxillary and mandibular teeth and crestal bone on one image.
Receptor: bitewing
Technique: bitewing
Purpose, receptor and technique of occlusal examination
Purpose: used to examine large areas of the maxilla and mandible on one image
Receptor: occlusal. Or bites on while receptor
Technique: occlusal
What is complete series/full mouth series?
Series of intraoral X-rays taken that show all tooth bearing areas of the jaws. Combines PA’s and BW’s. 14-20 images
Extra oral radiographic examinations include…
Panoramic, lateral jaw, cephalometric, posteroanterior, waters, submentovertex, reverse towne, transcranial, tomographic
Principles of paralleling technique
Receptor is placed in the mouth parallel to the log axis of the tooth
Central X-ray beam is directed at a right angle to the receptor
Beam alignment device (holder) must be used to keep the receptor parallel with the tooth
Patient prep before X-rays
Brief the pt on the procedure
Adjust the chair so pt is upright
Adjust headrest-maxilla must be parallel to the floor
Place and secure lead apron on pt
remove all objects from pt mouth (piercings, dentures, retainers etc)
Advantages and disadvantages of paralleling technique
Ad: accurate, simple, easily duplicated and compared to previous
Dis: receptor placement, child or adult with small mouth needs practice, discomfort
Bisecting technique- what’s it for?
PA’s
Based on the concept of bisecting the angle formed by the receptor and long axis of the tooth
Bisecting technique
Receptor is placed along lingual/palatal surface of tooth
Where receptor contacts the tooth the plane of the receptor and long axis form an angle
An imaginary bisector divides the angle in half
Central X-ray beam is directed at right angle to the imaginary bisector
Advantages and disadvantages of bisecting technique
Ad: can be used without beam alignment devices
Dis: image distortion, angulation problems
What can occlusal X-rays be used for
Locate retained roots Locate supernumerary, unerupted or inpacted teeth Locate salivary stones, foreign bodies Locate lesions, cysts, tumours etc Evaluate maxillary sinus Evaluate fractures of the jaws
What does panoramic imaging show?
Overall view of maxilla and mandible
All dentition and supporting structures
Supplements bws and pas
Evaluate impacted teeth
Eruption patterns, lesions and conditions of the jaw
Should not be used to diagnose caries, perio disease
What is the rotation centre?
The pivotal point or axis around which the receptor and X-ray tube rotate
What is focal trough?
A theoretical concept used to determine where the dental arches must be positioned to obtain the sharpest image. Defined as a 3D curved zone. Structures outside the focal trough appear blurry. The closer the rotation centre is to the teeth the narrower the focal trough.
Types of image resulting from panoramic X-rays
Real image
Double image- occurs when structure receives X-rays twice. Eg midline, hyloid, spine, tongue
Ghost image - when structure is outside of the focal trough but close to X-ray source eg earrings
Advantages and disadvantages of panoramic images
Ad: field size, simple to use, patient co-operation, minimal exposure
Dis: image quality - limitations due to focal trough, distortion, high cost of equipment
Advantages and disadvantages of digital X-rays
Ad: superior gray scale resolution (256 compared to 16-25), reduced exposure, increased speed, lower costs, time efficient, easier pt education and record keeping, allows to view and compare many images on the same screen, can be magnified, includes a measurement tool.
Dis: initial set up cost, image quality, size of sensor, wear and tear of sensors, legal issues, can’t heat sterilise sensor
Classification of caries
C0- no radiolucency
C1- RL confined to outer half of enamel (won’t see on X-ray)
C2- RL in inner half of enamal (won’t see on xray)
C3- RL extends beyond DEJ by 0.5mm
C4- RL has obvious spread in outer 1/3of dentine
C5- RL extends 2/3 into the dentine
