Radiography

Question 1

Types of intraoral radiographic examinations

Answer 1

Periapical
Interproximal
Occlusal

Question 2

Purpose, receptor and technique used for PA

Answer 2

Purpose: to examine the entire tooth (crown and root) and supporting bone
Receptor: pa receptor
Technique: 2 methods.. paralleling and bisecting

Question 3

Purpose, receptor and technique of interproximal examination

Answer 3

(BW) purpose: to examine crowns of maxillary and mandibular teeth and crestal bone on one image.
Receptor: bitewing
Technique: bitewing

Question 4

Purpose, receptor and technique of occlusal examination

Answer 4

Purpose: used to examine large areas of the maxilla and mandible on one image
Receptor: occlusal. Or bites on while receptor
Technique: occlusal

Question 5

What is complete series/full mouth series?

Answer 5

Series of intraoral X-rays taken that show all tooth bearing areas of the jaws. Combines PA’s and BW’s. 14-20 images

Question 6

Extra oral radiographic examinations include…

Answer 6

Panoramic, lateral jaw, cephalometric, posteroanterior, waters, submentovertex, reverse towne, transcranial, tomographic

Question 7

Principles of paralleling technique

Answer 7

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

Question 8

Patient prep before X-rays

Answer 8

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)

Question 9

Advantages and disadvantages of paralleling technique

Answer 9

Ad: accurate, simple, easily duplicated and compared to previous

Dis: receptor placement, child or adult with small mouth needs practice, discomfort

Question 10

Bisecting technique- what’s it for?

Answer 10

PA’s

Based on the concept of bisecting the angle formed by the receptor and long axis of the tooth

Question 11

Bisecting technique

Answer 11

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

Question 12

Advantages and disadvantages of bisecting technique

Answer 12

Ad: can be used without beam alignment devices

Dis: image distortion, angulation problems

Question 13

What can occlusal X-rays be used for

Answer 13

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

Question 14

What does panoramic imaging show?

Answer 14

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

Question 15

What is the rotation centre?

Answer 15

The pivotal point or axis around which the receptor and X-ray tube rotate

Question 16

What is focal trough?

Answer 16

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.

Question 17

Types of image resulting from panoramic X-rays

Answer 17

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

Question 18

Advantages and disadvantages of panoramic images

Answer 18

Ad: field size, simple to use, patient co-operation, minimal exposure
Dis: image quality - limitations due to focal trough, distortion, high cost of equipment

Question 19

Advantages and disadvantages of digital X-rays

Answer 19

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

Question 20

Classification of caries

Answer 20

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