Radiography Of Caries Flashcards
What is the role of radiographs in caries detection?
Can you select the appropriate radiographs for caries assesemnt?
Explain the cause of caries mimics on radiographs
Systemically review a dental radiograph for the presence of caries
What is caries
- 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
What causes demineralisation?
Lactic acid produced by bacteria
Describing carious lesions
- enamel / dentine / root
- primary / secondary
- recurrent / residual
- active caries (childhood / rampant)
- arrested or inactive
Blacks classifications of dental caries
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
Pitt’s classification of dental caries
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
How are Pitt’s classification of dental caries managed?
D1 and D2 lesions often managed with preventative measures
D3 or D4 will likely require restorative treatment
Diagnosis and detection of caries
- 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
Temporary elective tooth separation
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
Fibre optic trans illumination FOTI
Technique
- 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
Fibre optic trans illumination FOTI
Limitations
- better for detection of approximal caries than occlusal
- cannot be used near restorations
- need to turn lights off to see so inconvenient
Fluorescence
- 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
Fluorescence and caries detection
Fluorescence changes with density
Lower density of demineralisation and caries will alter fluorescence
Observed using digital imaging software
Radiography - how is it used to detect caries?
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
Advantages of radiographs?
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
Disadvantages of radiographs
BUT early lesions are difficult to detect
- 40% mineral loss required before visible on a radiograph
Bitewing radiography for?
Best radiograph for caries assessment
Bitewing radiograph advantages
- maximum coverage of ‘at risk areas’ for lowest dose
- high resolution image
- minimal superimposition of other anatomical structures
- reproducible technique
Features of a good quality Bitewing
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)
Bitewing radiographs are a reproducible technique, why is this important?
Important to see is caries is arrested or still developing
We can take Bitewing a to track the progress of caries development
Assess this radiograph
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
Other dental radiographs for caries detection - periapical
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
Other dental radiographs for caries detection - oblique lateral
Extra oral image with lower resolution than BW (detector outside of mouth)- advantage
Useful for caries diagnosis in young children
Other dental radiographs for caries detection - panoramic radiograph
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
Extra oral Bitewings
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
Caries causes
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
Demineralisation of enamel/ dentine =
Decrease in density =
Decrease in attenuation of x ray photons =
Area becomes more radiolucent (darker)
What is caries shown as in aradiogrpah
Radiolucency in the tooth
Occlusal caries
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
How does carious lesion in dentine look like
Triangle
Approximal caries
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
Buccal and lingual surfaces
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
Root surface caries
Usually detected clinically
Lesions involve cementum and dentine and are associated with gingival recession
Beware cervical burnout artefact
Recurrent caries
Also called secondary caries
Occurs adjacent to an existing restoration
Reporting caries
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
Create radiographic report
Problems with using radiographs for caries detection
- use of ionising radiation
- technique ‘ projection all issues
- clinical progression of caries verses radiographic appearance
- caries mimics
Ionising radiograph
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
Technique errors / film faults
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
Projection issue - overlapping contact points
X ray beam should pass parallel to contact point and hitting the image detector perpendicularly
= best separation and visibility of contact point
Projection issue - adjacent restorations
- superimposition of high density restoration will obscure low density caries
- caries in adjacent sites as secondary caries may not be visible in radiograph
Projections issue - localisation
- 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
Projection issue - caries depth
Depending on beam angle, a superficial lesion can be projected deeper
Eg , an enamel lesion can appear to be into dentine
Visibility of depth of lesion
- 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
Active or arrested caries for radiograph, can we tell?
Radiograph shows areas of demineralisation but gives no indication whether caries is active or not
Active or arrested caries for radiograph?
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
What if caries is into dentine?
We don’t monitor for progression, we treat it
Caries mimics
Causes of radiolucent on radiographs which can be mistaken for caries
- Tooth substance loss mot related to caries ( assessed through clinical examination)
- attrition / abrasion / erosion
- cracked cusp
- lost restoration - Radiolucent lining material - smooth radiolucent band deep to a large restoration
- Artefact
- cervical burn out artefact
- Mach effect artefact - Corrosion product
Cervical burnout artefact
- 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
Same teeth different exposure factors
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
Mach band effect
Areas of different contrast next to each other
Transition point looks darker
Corrosion products
Radiololucency deep to Amalgam restoration
Can mimic caries
When are radiographs indicated
Personalised based on risk factors
Assessing caries risk
FGDP selection criteria
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
European academy of paediatric dentistry
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
Q before taking radiographs
Has it been done already
Do i need it now
Is it the best investigation
Are they all needed
