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CSA > Radiography of caries > Flashcards

Radiography of caries Flashcards

describe role of radiographs

1
Q

what is caries definition?

A
  • multifactorial disease
  • infectious disease
  • lactic acid produced by bacteria causing demineralisation
  • Step mutant
  • balance between de and re mineralization
  • Demineralisation may extend well into dentine before cavitation occurs,
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2
Q
A
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2
Q

how can you describe carious lesions

A
  • enamel
  • dentine
  • root
  • primary
  • secondary
  • residual
  • active caries (early childhood, rampant)
  • arrested or inactive
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3
Q

describe blacks classification of dental caries

A

Class I - pit/fissure
Class II- interproximal areas of the posterior teeth
Class III- interpoximal surface of anterior teeth
Class IV- interporximal surface of anterior tooth involving the incisor edge
Class V - lesion affecting the cervical third of tooth

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4
Q

Describes Pitt’s Classification

A

D1- White/opaque or won lesion but surface hard and occlusal surface hard on probing
D2- slight loss of surface,s sticky issues, no dentine involvement
D3- Dentine involvement but not pulp
D4- possible or definite pulpal involvement
D1 and D2 lesions often managed with preventative measures
D3 or D4 will likely require restorative treatment

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5
Q

Describe diagnosis and detection of caries lesions

A

need to establish both presnce and activity of lesion
- primary detection method is visual inspection
(direct vision of clean, dry teeth under good lighting)
- additional detection methods
temporary tooth separation
fiberoptic transillumination
laser fluorescence
radiography

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6
Q

what is temporary elective tooth separation

A
  • interproimal surfaces
  • can’t see surface clincially
  • separated using bands placed between contact points
  • left for 1/2 weeks
  • separated teeth and allow clear vision
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7
Q

what is fire optic trans-illumination (FOTI)

A

technique
- white light shone into contact points through a 0.5mm diameter probe
- normal tooth scatters light
- caries reduces spread of light so appears darker than sound tooth
Limitations
- better for detection of approximate caires than occlusal
- cannot be used near restorations

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8
Q

describe how laser fluorescence is used to detect caries

A
  • light of a known wavelnthg is shown onto an obejct
  • the light scatters through the material
  • some of the light waves are absorbed
  • some lose energy and are emitted as waves with longer wavelength
  • fluorescence changes with density
  • lower density of demineralisation and caries will alter fluorescnce
  • observed using digital imaging software
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9
Q

how is radiography sued to detect caries

A
  • use of ionising radiation to create an image demonstrating differences in tissue density
  • demineralisation in caries reduces enamel /dentien density
  • can reveal lesions otherwise undetectable by clinical exam; pre cavitation, approximal surface
  • BUT early lesions are difficult to detect
    (40% mineral loss required before visible on a radiograph
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10
Q

what type of radiographs are used for caries detection?

A

Bitewings - small imaging detector on tongue side of teeth and placed in holder
patient bites on block
Periapical
Oblique lateral
Dental panorami
Extroral bitewings

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11
Q

Describe bitewing radiography?

A
  • gold standard radiograph for caries assessment
  • advantages
  • maximum coverage of ‘ at risk areas’ for lowest dose
  • high resolution image
  • minimal superimposition of other anatomical structures
    -reproducible tehcniqe
    Features of a good quality bitewing
  • should see medial contact point of first premolar to the most distal contact point
    -in adults, 2 radiographs may be required to cover all contact points on each side
  • no or minimal overlap of enamel
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12
Q

Describe other dental radiographs for caries detection

A

Periapical
- same resolution. to bitewing and minimal superimposition of adjacent anatomy
-however, fewer teeth shown on each film for a similar dose of ionising radiation

Oblique lateral
- extraoral image with lower resolution than bitewing
- useful for caries diagnosis in young children

Dental panoramic
- not indicated purely for caries diagnosis, unless unable to tolerate intraorals
-extraoral image with lower resolution
- Artefacts related to the moving x ray source and image receptor

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13
Q

describe extroral bitewings and the advantages

A
  • more comfortable for patients
  • better interproximal separation between contacts than a panoramic
  • 50% dose reduction than normal panoramic
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14
Q

Describe the disadvantages of extra oral bitewings

A
  • compared with intramural bitewings
  • higher dose
    lower resolution
    increased artefact less reproducible
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15
Q

Describe the appearance of caries

A
  • demineralisation of the inorganic portion of dental tissues
  • destruction of the organic portion
  • results in a decrease ind density compared with normal tooth and a more radiolucent appearance in the radiograph
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16
Q

what is occlusal caries

A
  • related to food debris and bacteria accumulating in pits and fissues
  • begins with decalcification of enamel
  • poorly seen on radiographs
  • when dentine is reached, caries appears to spread laterally- seen as triangular shape on radiographs
17
Q

describe approximal caries

A
  • medial and distal surfaces
  • early lesions may involve enamel only
  • spreads laterally In dentine
  • need good quality image to separate contact points and reveal low contrast lesions
18
Q

describe 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 surfaces
19
Q

describe root surface caries

A
  • usually detected clinically
  • lesions involve cementum and dentine and are associated with gingival recession
  • beware cervical burnout artefact
20
Q

describe recurrent caries

A
  • secondary caries
  • occurs adjacent to an existing restoration
    overhanging margins
    -deep to enamel
21
Q

describe process of reporting caries

A
  • systematic approach simialr to charting
  • assess each tooth individually
    -full crowns, enamel and dentine density
  • cervical margins
  • existing restoration
  • pulp chamber
    -reactive dentine
  • direct involvement
22
Q
A
23
Q

what are the probes. with using radiographs for caries detection

A

Ionising radiation
- damaging effect on tissue
-use must be justified - benefits outweigh risk
technique/projectional issues
- clinical progression of caries versus radiograph appearance
-caries mimics

24
Q

describe techqieu and projectional issues in radiographs

A
  • film faults/processing
    projectional issues related to beam angulation
  • overlapping contact points can obscure early lesions
  • superimposition of restorations
  • localisation to buccal/lingual surfaces
  • accuracy of depth of carious lesion
25
Q

describe technique erros/film faults in x rays

A

faults which can reduce image quality and make it harder to see caries
- film positioning so some contact points are missed
-poor contrast0 image too pale/toot dark
incorrect exposure settings
processing errors
artefact obscuring crowns
foreign object, chemical splash
- radiograph orientation for viewing

26
Q

why are adjacent restorations difficult to project

A
  • superimposition of high density restoration will obscure low density caries
  • caries in adjacent sites and secondary caries may not be visible in the radiograph
27
Q

how is localisation a projections issue?

A
  • cannot localise lesion to the buccal or lingual surface form a single radiograph
    both will look same
  • cannot assess bucco-lingual depth
28
Q

how is caires depth a projection issue

A

depending on beam angle, a superficial lesion can be projected deeper eg. an enamel lesion can appear into dentine

29
Q

describe the visibility of depth of lesion

A
  • 40% Mineral loss before a lesion becomes visible on a radiograph
  • lesions usually larger clinically than radiographically
  • very early lesions not evident at all
30
Q

describe diagnosis of active or arrested carries

A
  • a single radiographic shows area of demineralisation but gives no din cation on whether caries is currently active
  • follow up radiographs can show progression or stability of the lesion
    stable = arrested caires
    progression = active caries
    to assess change, radiographic technique must be reproducible
31
Q

describe caries mimics

A
  • cause of radiolucency on radiogprah which can be mistaken for caries
  • tooth substance loss not related to caries
    (attrition/abrasion/erosion
    cracked cusp
    lost restoration
  • radiolucent lining materials - smooth radiolucent band deep to a large restoration
  • artefact - cervcial burn out artefact. mach effect artefacts
  • corrosion products
32
Q

describe cervical burnout artefact

A
  • evident at cervical margin of tooth
  • caused by x rays oevrpentrating the thinner dentine at the tooth edge
    -superior to the alveolar bone and inferior to the enamel
  • triangular in shape, gradually less apparent towards too centre
  • cervical root edge should be intact albeit dark
  • usually all teeth in the radiograph with be affected
  • premolars most pronounced as they are smaller
33
Q
A
34
Q

what is the Mach band Effect

A
  • visual illusion
  • when uniformly dark area meets uniformly light area
35
Q

describe corrosion products

A
  • radiolucency deep to amalgam restoration
  • can mimic caries
  • deposits of heavy metal ions eg. tin, zinc in softened dentine
36
Q

when to image?

A
  • impotence of early caries detection
    preventative management and conservative treatment options
  • image shows current state of deminerlisation
    remineralisation only occurs at surface
    a single radiograph cannot distinguish between active or arrested lesion
    second image at a later time can reveal whether disease was active
  • decline in caires prevalence in recent decades
    fewer people with rapidly progressing lesions
    interval between examinations should be customised on basis of caries risk
37
Q

describe radiographs for caries in children

A

high caries risk group
moderate caries risk group
low caries risk group

38
Q

describe FGDP selection criteria

A

High risk
- posterior bitewings at 6 monthly intervals until no new or active lesions or patient changes into different risk category
Moderate risk
- annual posterior bitewings unless risk status alters
Low risk - posterior bitewings at 12-18 monthly intervals in primary dentition
2 years intervals in permanent dentition

39
Q

what questions should be asked prior to radiograph

A

has it been done already
do I need it now
is it the best investigation
are they all needed

CSA (32 decks)

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