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Clinical Skills - Dental Radiography > Radiography Of Caries > Flashcards

Radiography Of Caries Flashcards

1
Q

What is the role of radiographs in caries detection?

A
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2
Q

Can you select the appropriate radiographs for caries assesemnt?

A
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3
Q

Explain the cause of caries mimics on radiographs

A
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4
Q

Systemically review a dental radiograph for the presence of caries

A
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5
Q

What is caries

A
  • Multifactorial disease
  • Infectious disease
  • Lactic acid produced by bacteria causing demineralisation
  • Strep mutans
  • Balance between de- and re- mineralisation
  • demineralisation may extend well into dentine before cavitation occurs
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6
Q

What causes demineralisation?

A

Lactic acid produced by bacteria

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7
Q

Describing carious lesions

A
  • enamel / dentine / root
  • primary / secondary
  • recurrent / residual
  • active caries (childhood / rampant)
  • arrested or inactive
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8
Q

Blacks classifications of dental caries

A

Classified by surface of tooth involved

Class 1 - pit / fissure
Class 2 - inter-proximal areas of posterior teeth
Class 3 - inter-proximal surface of anterior teeth
Class 4 - inter-proximal surface of anterior tooth involving the incisal edge
Class 5 - lesion affecting the cervical third of the tooth

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9
Q

Pitt’s classification of dental caries

A

Levels of disease

D1 - white / opaque or brown lesion (surface/occlusion hard on probing)

D2 - slight loss of surface, sticky fissures, no dentine involvement

D3 - dentine involvement, no pulp

D4 - possible/definite pulpal involvement

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10
Q

How are Pitt’s classification of dental caries managed?

A

D1 and D2 lesions often managed with preventative measures

D3 or D4 will likely require restorative treatment

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11
Q

Diagnosis and detection of caries

A
  • Need to establish both presence and activity of lesion
  • Primary detection method - visual inspection of dry teeth under good light
  • Additional detection methods
    Temporary tooth separation
    Fibreoptic transillumination (FOTI)
    Laser fluorescence
    Radiography
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12
Q

Temporary elective tooth separation

A

Used for inter-proximal surfaces where you cant see clinically

Orthodontic band placed in between contact point and left for 1-2 weeks to allow orthodontic movement and shift the tooth to allow area to be seen visually or in radiographs

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13
Q

Fibre optic trans illumination FOTI

Technique

A
  • white light shone into contact points through a 0.5mm diameter probe
  • normal tooth scatters light
  • caries reduced spread of light so appears darker than sound tooth
  • observed clinically
  • better for approximal caries than occlusal
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14
Q

Fibre optic trans illumination FOTI

Limitations

A
  • better for detection of approximal caries than occlusal
  • cannot be used near restorations
  • need to turn lights off to see so inconvenient
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15
Q

Fluorescence

A
  • light of a known wavelength is shone onto an object
  • the light scatters though the materials
  • some of the light waves are absorbed
  • some lose energy and are emitted as waves with a longer wavelength
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16
Q

Fluorescence and caries detection

A

Fluorescence changes with density
Lower density of demineralisation and caries will alter fluorescence
Observed using digital imaging software

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17
Q

Radiography - how is it used to detect caries?

A

Use of ionising radiation to create an image demonstration differences in tissue density
- demineralisation in caries reduces enamel/dentine density
… hence will show as a different opacity on radiograph

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18
Q

Advantages of radiographs?

A

Can reveal lesions otherwise detectable by clinical exam
- pre cavitation
- approximal surfaces
.. shows occlusal caries but inter-proximal will give a high diagnostic yield on a radiograph

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19
Q

Disadvantages of radiographs

A

BUT early lesions are difficult to detect
- 40% mineral loss required before visible on a radiograph

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20
Q

Bitewing radiography for?

A

Best radiograph for caries assessment

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21
Q

Bitewing radiograph advantages

A
  • maximum coverage of ‘at risk areas’ for lowest dose
  • high resolution image
  • minimal superimposition of other anatomical structures
  • reproducible technique
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22
Q

Features of a good quality Bitewing

A

Should see mesial contact point of the first premolar to the most distal contact point

In adults, 2 radiographs may be required to cover all contact points on each side (dentition may be too large to fit in 1)

No or minimal overlap of enamel
- up to half thickness of enamel is acceptable
(Less than 50% overlap between teeth is a good Bitewing)

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23
Q

Bitewing radiographs are a reproducible technique, why is this important?

A

Important to see is caries is arrested or still developing

We can take Bitewing a to track the progress of caries development

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24
Q

Assess this radiograph

A

Right horizontal Bitewing of an adult

Contact point 8-7 is the most distal contact point

Pt has 3rd molars and the teeth an large, we’ve taken 2 Bitewing

Maxillary and mandibular crowns

Enamel has less than 50% overlap

Second radiograph taken further anteriorly hence larger than 50% overlap in some areas

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25
Q

Other dental radiographs for caries detection - periapical

A

Same resolution contrast appearance to Bitewing and minimal superimposition of adjacent anatomy

Fewer teeth shown on each film for a similar dose of ionising radiation

Less info about caries but more information about eg periapical tissues

26
Q

Other dental radiographs for caries detection - oblique lateral

A

Extra oral image with lower resolution than BW (detector outside of mouth)- advantage

Useful for caries diagnosis in young children

27
Q

Other dental radiographs for caries detection - panoramic radiograph

A

X-ray detector and tube are on opposites sides of the pt and they go in a circle - movement of both reduces the sensitivity of caries diagnosis and increases overlap of adjacent teeth

Lower contrast because of increased superimposition of surrounding structures

Not indicated purely for caries diagnosis, unless unable to tolerate intraorals

Extra oral image with lower resolution

Artefacts related to the moving x ray source and image receptor

28
Q

Extra oral Bitewings

A

Available on some newer panoramic units

Requires pt on same machine with everything going round in a circle
Movement of X-ray detectors and beam is changed to reduces curve - image is straighter in posterior areas so contact points are separated and reduces some of the artefact seen on full panoramic

Sectional panoramic only shows some areas, lower dose than full panoramic but higher dose than BW

Less reproducible - small change in unit = large change in radiograph

Good for a child that cant tolerate intraoral BW

29
Q

Caries causes

A

Demineralisation of the inorganic portion of dental tissues
Destruction of the organic portions

Results in a decrease in density compares with normal tooth and a more radiolucent appearance in the radiograph

30
Q

Demineralisation of enamel/ dentine =

A

Decrease in density =

Decrease in attenuation of x ray photons =

Area becomes more radiolucent (darker)

31
Q

What is caries shown as in aradiogrpah

A

Radiolucency in the tooth

32
Q

Occlusal caries

A

Related to food debris and bacteria accumulating in pits and fissures

Begins with decalcification of the enamel - poorly seen on radiographs

When dentine is reached, caries spread laterally - seen as triangle shape on radiographs

33
Q

How does carious lesion in dentine look like

A

Triangle

34
Q

Approximal caries

A

Mesial and distal surfaces

Early lesion may involve enamel only

Spreads laterally in dentine

Need good image quality to separate contact points and reveal low contrast lesions

35
Q

Buccal and lingual surfaces

A

Can arise in pits and fissures

When small lesions are usually round becoming more elliptic or semilunar when large

D not widen to occlusal surface

Cant distinguish between buccal / lingual have to look in mouth

36
Q

Root surface caries

A

Usually detected clinically

Lesions involve cementum and dentine and are associated with gingival recession

Beware cervical burnout artefact

37
Q

Recurrent caries

A

Also called secondary caries

Occurs adjacent to an existing restoration

38
Q

Reporting caries

A

Systematic approach to similar charting

Assess each tooth individually
- full crowns, enamel and dentine density
- cervical margins
- existing restorations
- pulp chamber - tertiary or reactive dentine - bridging the gap between the caries or the pulp / direct involvement - deep caries

URQ -> ULQ -> LLQ -> LRQ

39
Q

Create radiographic report

A
40
Q

Problems with using radiographs for caries detection

A
  • use of ionising radiation
  • technique ‘ projection all issues
  • clinical progression of caries verses radiographic appearance
  • caries mimics
41
Q

Ionising radiograph

A

Damaging effect on tissue
- deterministic eg skin erythema
- stochastic eg cancer

Use must be justified
- benefits must outweigh risk

In dentistry we worry about stochastic as the dose is too low for deterministic

X rays must be justified

42
Q

Technique errors / film faults

A

Faults which cam reduce image quality and male it harder to see caries

Film positioning - so some contact points are missed

Poor contrast - image too pale / dark
- incorrect exposure settings
- processing errors

Artefact obscuring crowns
- foreign object eg copper dot
- chemical splash (from wet film processing)

Radiograph orientation for viewing

43
Q

Projection issue - overlapping contact points

A

X ray beam should pass parallel to contact point and hitting the image detector perpendicularly

= best separation and visibility of contact point

44
Q

Projection issue - adjacent restorations

A
  • superimposition of high density restoration will obscure low density caries
  • caries in adjacent sites as secondary caries may not be visible in radiograph
45
Q

Projections issue - localisation

A
  • cannot localise lesion to the buccal or lingual surface from a single radiograph - both will look the same
  • cannot assess buccal-lingual depth or how deep it extends to the pulp chamber
46
Q

Projection issue - caries depth

A

Depending on beam angle, a superficial lesion can be projected deeper
Eg , an enamel lesion can appear to be into dentine

47
Q

Visibility of depth of lesion

A
  • 40% mineral loss before a lesion become visible on a radiograph
  • lesions usually larger clinically than radiographically
  • very early lesions not evident at all

Bridging of dentine where caries is deep shown on radiograph - clue that lesion is deeper than what we can see on radiograph

48
Q

Active or arrested caries for radiograph, can we tell?

A

Radiograph shows areas of demineralisation but gives no indication whether caries is active or not

49
Q

Active or arrested caries for radiograph?

A

Follow up radiographs can show progression or stability of the lesion

Stable = arrested caries
Progression = active caries

To asses change radiographic technique must be reproducible

50
Q

What if caries is into dentine?

A

We don’t monitor for progression, we treat it

51
Q

Caries mimics

A

Causes of radiolucent on radiographs which can be mistaken for caries

  1. Tooth substance loss mot related to caries ( assessed through clinical examination)
    - attrition / abrasion / erosion
    - cracked cusp
    - lost restoration
  2. Radiolucent lining material - smooth radiolucent band deep to a large restoration
  3. Artefact
    - cervical burn out artefact
    - Mach effect artefact
  4. Corrosion product
52
Q

Cervical burnout artefact

A
  • evident at cervical margin of tooth
  • caused by X-rays photons over penetrating thinner dentine at the tooth edge
    (superior to the alveolar bone and inferior to the enamel)
    Area less dense naturally which gives the appearance of a lucent area
  • triangular in shape, gradually less apparent towards tooth centre
  • cervical root edge should be intact albeit dark
    Premolars most pronounced because they are smaller
53
Q

Same teeth different exposure factors

A

Decrease kilo volt of x ray photons and so they aren’t as penetrating anymore

Area mesial of 6 that looks radiolucent and looks like root caries disappears because its not pathology its sound tooth

54
Q

Mach band effect

A

Areas of different contrast next to each other
Transition point looks darker

55
Q

Corrosion products

A

Radiololucency deep to Amalgam restoration
Can mimic caries

56
Q

When are radiographs indicated

A

Personalised based on risk factors

57
Q

Assessing caries risk

A
58
Q

FGDP selection criteria

A

High risk
- posterior BW at 6 monthly intervals until no new or active lesions or pt changes into different risk category

Moderate risk
- annual posterior BW unless risk status alters

Low risk
- posterior BW 12-18 month intervals in primary dentition
- 2 year intervals in permanent dentition

59
Q

European academy of paediatric dentistry

A

High and low risk
BW only if considered necessary for treatment
For both groups BW should be considered at
5 yrs
8-9 yrs
12-14 yrs

60
Q

Q before taking radiographs

A

Has it been done already
Do i need it now
Is it the best investigation
Are they all needed

Clinical Skills - Dental Radiography (2 decks)

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