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Dentistry and Oral Surgery > Diagnostic Imaging > Flashcards

Diagnostic Imaging Flashcards

1
Q

The majority of dental pathologies effecting companion
animals have?

A

radiographically detectable signs

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2
Q

Periodontitis, the most common oral disease, is typified by?

A

Progressive apical migration of
the gingival attachment and associated bone loss, detectable by radiography

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3
Q

The findings of two studies reveal that clinically significant disease, of apparently healthy teeth, is identified in approximately how many dogs and cats?

A

30% of dog and 40% of cat dental radiographs.

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4
Q

Performing
dental radiography of diseased teeth was found to demonstrate clinically useful information in over how many cases?

A

Three quarters of cases.

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5
Q

Perfection is not mandatory when performing dental radiographs. The operator should
strive for?

A

Clinically diagnostic images and not become so focused on identification of the “angles” involved that it inhibits the flow of the procedure.

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6
Q

There are 2 basic components to a dental radiographic system, what are they?

A

X-ray generation
and
Image capture

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7
Q

Dental X-ray generators are comparatively low power units and as such are considered very safe. The majority have?

A

Fixed kV, commonly 60-70kV, and mA with the ability to alter the
time of exposure.

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8
Q

Dental X-ray generators produce comparatively few X-rays and previously could be used in
non-specific treatment areas. A recent change in radiation protection regulations requires that?

A

Controlled areas extend at least 2 meters from the primary beam, usually considered to be the edge of
the table unless interrupted by a suitably attenuating barrier, such as a brick wall. All entrances to
the controlled area must have automatic warning lights. In order to minimise scatter it is advisable to use a lead-vinyl sheet placed under the head.

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9
Q

Image capture is performed via standard X-ray sensitive film, what two kinds?

A

Phosphorescent plates used in indirect digital systems or by a digital sensor for direct digital radiography.

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10
Q

Dental film sizes, including digital screens, have standardised dimensions, What are these?

A

0 to 4
with 0 the smallest

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11
Q

Dental film is
available in different speeds, what are they?

A

E and F being the fastest and as such they can reduce the radiation exposure to operator and patient.

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12
Q

Direct digital sensors are only available in what size?

A

2 and smaller due
to the cost of manufacture of larger sizes being too great

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13
Q

Direct digital (DR) and indirect digital (CR) systems have much in common. Image
acquisition is rapid, how fast for DR and CR?

A

3-5 seconds for DR and approximately 10 seconds for size 2 CR screens. The
larger the screen size the longer the acquisition time via CR

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14
Q

DR sensor size limitations can be compensated for by?

A

Taking multiple views of the same tooth, roots and crown separately.

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15
Q

There are 3 main dental radiographic positioning techniques:

A

Intra-oral parallel technique, (IOP) Bisecting Angle (BA) and Extra-Oral

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16
Q

To evaluate the periodontal tissues fully, it is advisable to include a minimum of how much of the radicular tissue?

A

three millimetres of the radicular tissues surrounding the tooth’s root.

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17
Q

The close association and specific orientation of the teeth mean that orthogonal views are
only possible for which teeth?

A

Canine teeth

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18
Q

The intra-oral parallel technique can be utilised to acquire what views?

A

Lateral view of the mandibular molar
teeth and 4th premolar teeth and the third premolar tooth in some individuals.
The mandibular incisor and canine teeth
as a rostra-caudal view. The curvature of the roots of these teeth result in a near parallel view without affecting the diagnostic value of the radiograph, although the crowns of the teeth will be fore shortened.

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19
Q

What is the bisecting angle (BA) technique used for?

A

The BA technique is used for imaging all of the maxillary teeth, the lateral view of the mandibular canine teeth and the lateral view of the rostral mandibular premolars.

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20
Q

The use of the extra-oral technique reduces what?

A

The impact of the zygomatic superimposition on the roots.

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21
Q

How is an extra-oral x-ray taken?

A

With the patient in lateral recumbency and the palate perpendicular to the table the screen
is placed, extra-orally, under the cheek of the dependent arcade. The cusps of the maxillary teeth
are level with the most ventral border of the screen. The mouth is briefly propped open, (it is important to limit the time of near maximal mouth opening in cats as this can result in circulatory compromise to the brain) (Barton-Lamb, Martin-Flores, Scrivani, Bezuidenhout, Loew, Erb, Ludders) (Martin-Flores, Scrivani, Loew,
Gleed, Ludders). The X-ray beam is angled from the dorsal aspect across the palette at approximately
20 degrees to the axis of the vertical. This results in a near dimensionally accurate image of the
dependant maxillary premolar teeth and molar tooth, although some elongation wile evident. It is
important that the beam is angled sufficiently to prevent the superimposition of the crowns of the
contralateral premolar teeth over the root apices of the target teeth.

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22
Q

Conventional radiography utilises an orthogonal view to examine the relative position of overlying structures but
this is not possible in dental radiography due to anatomical constraints. Dental radiography utilises
tube shift to mitigate this constraint. Tube shift describes?

A

A rostral or caudal movement of the X-ray
generator from a truly lateral or rostro-caudal direction.
Overlying structures are separated by this
movement

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23
Q

What is the SLOB rule?

A

The SLOB rule notes that the lingual structure will move in the same direction as the tube shift and the buccal structure will move in the opposite direction to the tube shift
(S.ame L.ingual O.pposite B.uccal).

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24
Q

When is the SLOB rule most helpful?

A

This is of benefit when evaluating individual overlying roots of three rooted teeth, such as the maxillary 4th premolar.
Similarly, pathology or artefact of anatomy can be distinguished, the middle mental foramen can appear as a
lucency of the mesial root of the 2nd mandibular premolar but these structures can be separated
with tube shift and this would not be possible in the presence of true pathology.

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25
What is the first step in the evaluation paradigm?
The initial step in the evaluation paradigm is to assess whether the radiograph is truly diagnostic. The primary evaluation process is similar to that performed for conventional radiographs.
26
How can a radiograph be assessed if it is diagnostic?
* Is the structure of interest centred in the field of view? * In the case of a tooth or teeth, is sufficient peri-radicular tissue (at least 3mm around the apex of the tooth root) evident? * Is the radiograph of appropriate exposure and is there sufficient contrast? * Is there significant distortion of the target structures? * What are the normal structures in the field of view and by elimination what are pathological? (Take care to appreciate marginal structures as peripheral pathology can be easily missed.) * Are additional images required to fully evaluate the structure. * Would comparison of the contralateral tissues provide benefit for comparison? * Are follow up radiographs indicated and if so when?
27
When viewing a dental x-ray the convention for image orientation is referred to as?
lingual mounting.
28
How do images appear when lingually mounted?
Radiographs should be orientated as if the observer were looking into an open mouth, facing them with the crowns of all teeth pointing toward the tongue, hence the maxillary teeth are orientated with the cusps pointed downwards and the mandibular cusps pointed up. Lingual mounting will allow identification of left and right arcades.
29
Enamel can vary in thickness from?
0.1mm to 1mm (Crossley 1995).
30
The cervical region of the tooth (the narrowing between the crown and the root) does not have enamel or bone overlying it and can therefore appear to be more radiolucent than the crown or root. This lucency, referred to as the ............... should not be mistaken for pathology.
cervical burnout
31
The alveolus is separated radiographically from the root by a thin, radio-lucent line which represents the?
periodontal ligament space (PLS).
32
The PLS should conform closely to the outline of the root closely. Widening (the PLS being more than twice the width of comparator teeth/ regions of the root), irregularity or loss of the PLS may represent?
the presence of pathology
33
A thin, radioopaque line may surround the periodontal ligament, the lamina dura. The lamina dura is?
The dense bone of the lining of the alveolus
34
Although the roots of the teeth are covered in cement, this layer is not radiographically evident unless it is?
Grossly thickened as seen in cases of hypercementosis.
35
Loss of the PLS may indicate ....... of the tooth and loss of the lamina dura may indicate apical .........
Ankylosis Periodontitis
36
What are chevron lucencies?
The maxillary incisor and canine teeth, and in some instances the mandibular incisors, may have apparent widening of the PLS at their apical limit. This widening does not have an irregular outline and continually tapers following the axis of the PLS. These are referred to as chevron lucencies. These lucencies must be differentiated from pathology. They appear due to a contrast in radio-density between the more dense alveolar and incisive bone and the less dense trabecular bone around the apex of the roots (DuPont & DeBowes 2008).
37
Dramatic discrepancy of the alveolar margin’s height along the arcade is likely to represent?
periodontal disease
38
Why can the pulp and dentine can be considered as a single anatomical complex?
As projections from odontoblasts that line the pulp cavity penetrate into the dentine via dentinal tubules.
39
What forms dentine?
Odontoblasts produce the dentine that forms the tooth. Deposition of dentine occurs throughout life aslong as the vitality of a tooth is maintained but is most rapid during early tooth development
40
On eruption the crown is fully formed, but the root is comprised of?
A thin shell of dentin with an incomplete and open apex and very wide pulp.
41
Once the apex is complete dentine deposition slows but can be increased in response to?
Pulp stimulation caused by insults such as abrasion, fracture or carious injury of the crown and exposure of dentinal tubules.
42
Cessation of dentin deposition indicates?
Pulp necrosis which may be seen with concussive injuries or fractures in which the pulp is exposed.
43
How can we use dentine deposition radiographically?
Radiographically, we can utilise this development to evaluate the vitality of teeth by comparison with the contralateral tooth or repeating a radiograph some months later. Chronic pulpitis may result in excess deposition of dentin, resulting in an irregular narrowing of the pulp cavity.
44
The usual number of tooth roots for a specific tooth is well known but there can be variation. Ten percent of maxillary 3rd premolar teeth of the domestic cat will have?
An accessory root (Verstraete et al 1996) and may also be seen in dogs.
45
The middle and caudal mental foramina can be misinterpreted as?
Apical lucencies, as they can overly the apex of the mandibular premolar tooth roots.
46
The middle mental foramen is often level with the?
Mesial root of the 2nd mandibular pre-molar tooth of the dog
47
The maxillary palatine fissures are normal anatomical D-shaped lucencies. These symmetrical structures are seen as what on radiographs?
Radiolucent regions immediately caudal to the incisive bone and on either side of the midline
48
The nasal surface of the alveolar process of the maxilla can be appreciated as a radioopaque line immediately apical to the roots of the maxillary canine, premolar and rostral molar teeth. If this line becomes indistinct or broken, this can indicate?
Development of severe apical pathology such as oro-nasal fistula formation.
49
Exposure of the furcation results in a privileged micro-environment where the abrasive effects of a brush cannot remove plaque and thus creates?
an inability to prevent disease progression.
50
What is stage 2 periodontal disease?
If root exposure is less than 25% this can be classified as stage 2 periodontal disease (Wolf et al 2005)
51
What is stage 1 periodontal disease?
Gingivitis without architectural change to the alveolar margin is stage 1.
52
What is stage 3 periodontal disease?
classified as 25-50% root exposure
53
What is stage 4 periodontal disease?
Rreater than 50% root exposure.
54
How can the periodontal staging system be utilised?
The classifications can be utilised to inform what potential management options are appropriate. Stage 1, effective home care alone is likely to be successful whereas stage 3 has a guarded prognosis and is likely to require significant surgical intervention and regular long-term follow-up in addition to home care.
55
How does pulp necrosis appear on radiographs?
Pulp necrosis, resulting from pulp exposure or concussive trauma will initiate an apical periodontitis. This is typified by widening of the PLS around the apex of the root, focal loss of the lamina dura and irregularity to the outline of the PLS. The apical root surface may appear irregular and less distinct at its margins, consistent with external inflammatory root resorption.
56
What can apical periodontitis progress to?
Apical periodontitis may progress to development of apical granuloma or apical abscess formation
57
Intrinsically stained teeth, loss of the normal pearlescence of the tooth often with pink to brown discolouration, is highly associated with?
Irreversible pulpitis and pulp necrosis
58
How can you assess if irreversible pulpitis and pulp necrosis has occured?
Serial radiographs separated by 4 to 6 months’ time may provide information on the vitality of these teeth, if there is any doubt.
59
How many cats are effected by tooth resorption?
Greater than one third of the population has been reported to be affected (Pettersson & Mannerfelt 2003) and up to 70% of pure breed cats (Girrard etc al 2009).
60
What is Type 1 resorption in cats?
Type 1 resorption is believed to be of an inflammatory aetiology and may represent a response to periodontitis in susceptible cats. As a result, the resorption lacunae, seen radiographically as an irregular lucency of the tooth’s structure, will always initiate at the cemento-enamel junction. The resorption may progress, weakening the tooth and causing crown fracture but the remaining root structure is unlikely to be affected. As a result, type 1 resorption always requires complete extraction of the remaining root.
61
What is Type 2 resorption in cats?
Type 2 resorption is currently considered idiopathic although appears to have a genetic component with osteoclast Vitamin-D receptor function up regulating their activity implicated. The resorption process may be initiated at any point along the surface of the tooth’s root and is commonly followed by replacement of the root’s structure with bone. Loss of a distinct PDS is likely and consistent with tooth ankylosis. Loss of a defined tooth root and root canal may also be seen in more advanced cases. Where complete loss of root structure is evident, coronectomy of the remaining crown is indicated and indeed attempted extraction would be contra-indicated as there is no root to extract (Mihaljevic et al 2012)
62
Unexpected missing teeth should always be what?
investigated radiographically
63
The adult formulae for the dog is:
3/3I 1/1C 4/4Pm 2/3M
64
The adult formulae for the cat is:
3/3I 1/1C 3/2PM 1/1M
65
Extraction should always be considered for roots unintentionally retained, especially if?
There are inflammatory changes evident radiographically, the root canal is evident, clinical symptoms are consistent with active disease and the level of surgical trauma would not outweigh the benefit of extraction.
66
Where teeth do not erupt there is the potential for the formation of an?
Odontogenic cyst, termed a dentigerous cyst .
67
Why do dentigerous cyst form?
These cysts are derived from fluid filling the dental follicle and appear as a radiolucent lesion in which a tooth-like structure can be seen, consistent with the un-erupted tooth. Adjacent teeth may be affected by the cyst and may require extraction. Cysts can expand dramatically and potentially result in pathologic fracture of the mandible (Kouhsoltani et al 2015) or rupture into the nasal cavity. Early identification is important to prevent severe pathology and so assessment at neutering for missing teeth is advised.
68
Focal enamel defects or pits most commonly on the occlusal surfaces of the molar teeth of dogs and may represent the development of?
dental caries
69
How do caries develop?
Caries lesions develop as a result of fermentation of dietary sugars by specialised bacteria and the production of acidic by-products of fermentation. These organic acids demineralise the inorganic components of the enamel and allow organic decay of dentin.
70
How do Caries appear radiographically?
The typical radiographic appearance is of a well-defined circular lucency of the crown of the tooth with loss of enamel and dentin (Duncan 2010). Involvement of the pulp chamber may be seen as may apical periodontitis, consistent with endodontic involvement of the carious process.
71
Oral masses with evidence of osteolysis or induction of a periosteal response may be suggestive of?
a more invasive, potentially malignant, process and careful screening and targeted deep biopsy would be appropriate before attempting definitive treatment. The radiographic differentiation between the appearance of neoplasia and osteomyelitis is challenging and an open mind should be maintained until histological diagnosis is made (Petrikowski 1995).
72
The diagnostic yield of computed tomography in patients suffering maxillofacial trauma is 1.6 times greater than conventional radiography in dogs and 2 times greater in cats (Bar-Am etc al 2008), indicating their diagnostic power.
73
CT machines may be described as?
Single, dual or multislice units and this relates to the number of slice images generated per gantry revolution.
74
The greater the number of slices the faster the CT capture occurs which is beneficial in imaging techniques such as CT angiography. The size of a multi-slice detector determines the smallest possible slice thickness.
75
What is CT radiation measured in?
The measurement of radiation attenuation is calculated in Hounsfield units. Distilled water has a Hounsfield unit of 0, air -1000, soft tissue 20-80 and bone +200 to +3000HU. Hounsfield units can be measured for a given area of a CT. This is particularly useful when differentiating fluid from soft tissue densities as may be seen in the nasal or sinus cavities.
76
When using CT what does adjusting window scales do?
Images can also be manually altered by changing the “windowing” applied which will adjust the greyscale of the image. Window level affects the brightness of an image, decreasing window level will increase brightness. Window width is a measure of the range of Hounsfield Unit numbers displayed and effects the grey-scale contrast. Wide windows are used to examine bone and narrow windows used in reviewing soft tissue.
77
What are wide and narrow windows used for with CT?
Wide windows are used to examine bone and narrow windows used in reviewing soft tissue.
78
Intravenous injection of iodine containing compounds will allow for?
Identification of tissue with increased blood supply and or vascular permeability
79
Contrast media are indicated for assessment of?
Potential invasion of neoplastic lesions. Non-ionic forms of contrast agent are preferred for intravenous use as they exert less osmotic pressure and are associated with fewer complications.
80
What are the complications of injection of contrast agents?
Complications of administration of contrast have been reported an include anaphylactic reactions, hypotension, inducement of vomiting and delayed allergic reaction.
81
What is the best way to position for CT?
Patients are placed in sternal recumbency facing forward into the gantry. The head is positioned so that the palate is parallel to the surface of the patient table and the mouth is held partly open with a radiolucent spacer (such as the barrel of an appropriate sized syringe). Removal of tissue not intended to be imaged from the field of view is appropriate to improve image quality, such as folding the forelimbs back against the chest when imaging of the head alone is required. The author advises scanning from the external nares to mid neck to include the medial retro-pharyngeal lymph nodes.
82
How many radiographs in a canine full mouth series?
14
83
How many radiographs in a feline full mouth series?
10
84
What is the alveolar ridge?
85
Show some non-dental anatomy of the maxilla?
86
Show the palatine fissures?
87
Show are tooth with an accessory root?
88
Show a tooth with gemination?
89
Show intra-radicular grooves?
90
Show apical periodontitis?
91
Show a perio-endo lesion?
92
Show tooth impaction?
93
Show luxation?
94
Show oral neoplasia?
95

Dentistry and Oral Surgery (44 decks)

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