Small animal dental radiology and radiography Flashcards
Describe the two types of dental x-ray machienes
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
What is direct dental radiography?
Image sent straight to computer; no processing needed
Describe the advantages and disadvantages of direct dental radiography
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
What is indirect dental radiography?
Digital film that needs to be processed after exposure
Describe the advantages and disadvantages of indirect dental radiography
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
Why should dental radiography be performed?
- 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)
Which anatomical features are radiologically assessed?
- Abnormal number or shape of roots
- Extra or ‘missing’ teeth
Which pathological features are radiologically assessed?
- Periodontitis
- Pulp necrosis
- Dental fractures
- Tooth resorption (FORLs)
- Supernumerary teeth
- Un-erupted teeth/dentigerous cysts
What would be a normal incidental finding in a young dog on radiography
Pulp stone
- the pulp cavity hasn’t yet closed, they are still growing and receiving a blood supply at the apex
How is the pulp cavity different in older dogs?
It has narrowed and there is a rim of bone at the base of the root
If root furcation expose is seen on radiography what decision should be made?
To remove any teeth with root furcation exposed
Compare horizontal and vertical bone loss
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
Describe the features of a type 1 resorptive lesion
- Destruction of tooth with preserved periodontal ligament
- May also see concurrent root exposure and/or bone loss
- Open extraction indicated
Describe the features of a type 2 resorptive lesion
- Destruction of tooth with destruction of periodontal ligament – note absent periodontal space on affected tooth
- Coronectomy indicated
Which pathological lesions may occurs to the roots?
- Fracture
- Bone loss
How can the pulp be pathologically affected?
- Widening
- Loss of normal periodontal space around apex of tooth = apical lucency
- Pulpitis with a developing tooth root abscess = extraction needed
Parallel radiography is used for which teeth?
Caudal mandibular molars and premolars
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?
Bisecting angle
Describe how to set up and perform the parallel technique
- 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
Describe how to set up the sensor and beam for the bisecting angle technique
- Sensor at an angle to the teeth
- Beam perpendicular to the bisecting angle between the tooth root axis and the sensor
Why use the bisecting angle technique?
- Can radiograph teeth where a parallel technique is not possible
- Prevents image distortion from trying to take parallel views in hard to reach places
Describe positioning a patient for a bisecting angle view for an image of the molars and premolars
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
Describe performing a bisecting angle view for an image of the molars and premolars
- 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
Describe how patients need to be positioned for radiographs of each teeth
Lateral - mandibular molars
Sternal - maxillary M/PM, maxillary canines and incisors
Other lateral - Mandibular molars
Dorsal - mandibular PM, mandibular incisors and canine
What factors of radiation safety need to be considered?
- 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
