Small animal dental radiology and radiography

Question 1

Describe the two types of dental x-ray machienes

Answer 1

Multidirectional generator head:
- Mobile head attached to stand/wall mounted
- Limitless positions – can set to angle needed
- Reduce movement during procedure
Hand-held generator:
- Easier to store/set up in practice
- May see some movement during exposures
- Can be harder to set angles
- Care with setting up control zones and operator safety

Question 2

What is direct dental radiography?

Answer 2

Image sent straight to computer; no processing needed

Question 3

Describe the advantages and disadvantages of direct dental radiography

Answer 3

Advantages:
• No need to move sensor between exposures – easier to correct positioning faults
• Faster = less GA time
• Sensor has long lifespan of use
• Sensor small, easy to move and store. 
Disadvantages: 
• One size – doesn’t fit all well

Question 4

What is indirect dental radiography?

Answer 4

Digital film that needs to be processed after exposure

Question 5

Describe the advantages and disadvantages of indirect dental radiography

Answer 5

Advantages
• Size flexibility: Variety of shapes and sizes of films
• Films thin and easy to place into the mouth
Disadvantages:
• Slower: removing the film to be processed
• Less accurate: For the same reason, harder to correct positioning faults
• Films susceptible to damage

Question 6

Why should dental radiography be performed?

Answer 6

• Provides more accurate diagnosis
• Plan treatment appropriately
• Identify problems going on below the gum line
• Some problems are treated differently depending on radiographic appearance (feline dental lesions)

Question 7

Which anatomical features are radiologically assessed?

Answer 7

• Abnormal number or shape of roots

- Extra or ‘missing’ teeth

Question 8

Which pathological features are radiologically assessed?

Answer 8

• Periodontitis
• Pulp necrosis
• Dental fractures
• Tooth resorption (FORLs)
• Supernumerary teeth
• Un-erupted teeth/dentigerous cysts

Question 9

What would be a normal incidental finding in a young dog on radiography

Answer 9

Pulp stone

- the pulp cavity hasn’t yet closed, they are still growing and receiving a blood supply at the apex

Question 10

How is the pulp cavity different in older dogs?

Answer 10

It has narrowed and there is a rim of bone at the base of the root

Question 11

If root furcation expose is seen on radiography what decision should be made?

Answer 11

To remove any teeth with root furcation exposed

Question 12

Compare horizontal and vertical bone loss

Answer 12

Horizontal - Line of mandible is dropped compared to normal
Vertical - bone is receding perpendicular to normal line of the mandible
- both show a degree of root exposure

Question 13

Describe the features of a type 1 resorptive lesion

Answer 13

• Destruction of tooth with preserved periodontal ligament
• May also see concurrent root exposure and/or bone loss
• Open extraction indicated

Question 14

Describe the features of a type 2 resorptive lesion

Answer 14

• Destruction of tooth with destruction of periodontal ligament – note absent periodontal space on affected tooth
• Coronectomy indicated

Question 15

Which pathological lesions may occurs to the roots?

Answer 15

• Fracture

- Bone loss

Question 16

How can the pulp be pathologically affected?

Answer 16

• Widening
• Loss of normal periodontal space around apex of tooth = apical lucency
• Pulpitis with a developing tooth root abscess = extraction needed

Question 17

Parallel radiography is used for which teeth?

Answer 17

Caudal mandibular molars and premolars

Question 18

For all other teeth in the mouth we need to work around superimposition of other tissues (skull, opposite arcade) and limitations of sensor placement. We do this by using which technique?

Answer 18

Bisecting angle

Question 19

Describe how to set up and perform the parallel technique

Answer 19

• Patient in lateral with side to be examined up
• Sensor parallel to teeth
• Beam perpendicular to sensor
• In larger dogs may need to composite images for arcade

Question 20

Describe how to set up the sensor and beam for the bisecting angle technique

Answer 20

• Sensor at an angle to the teeth

- Beam perpendicular to the bisecting angle between the tooth root axis and the sensor

Question 21

Why use the bisecting angle technique?

Answer 21

• Can radiograph teeth where a parallel technique is not possible
• Prevents image distortion from trying to take parallel views in hard to reach places

Question 22

Describe positioning a patient for a bisecting angle view for an image of the molars and premolars

Answer 22

Position patient so region of interest is on top:
• Patient in sternal for maxillary teeth
• Patient in dorsal (upside down!) for mandibular teeth
- For larger dogs multiple exposures may be needed to image the whole arcade

Question 23

Describe performing a bisecting angle view for an image of the molars and premolars

Answer 23

• Sensor across mouth, rest crown of teeth being imaged on closest edge of sensor
• Bisecting angle between root and sensor
• Beam direction perpendicular to the bisecting angle

Question 24

Describe how patients need to be positioned for radiographs of each teeth

Answer 24

Lateral - mandibular molars
Sternal - maxillary M/PM, maxillary canines and incisors
Other lateral - Mandibular molars
Dorsal - mandibular PM, mandibular incisors and canine

Question 25

What factors of radiation safety need to be considered?

Answer 25

• Lead gown and thyroid shield
• Body dosimeter under gown
• Wrist dosimeter
• Controlled X-ray zone – whole room
• Beam directed towards ground
• Lead matting under patient