radiography of Caries Flashcards
awareness of different methods of caries diagnosis know what caries looks like on a radiograph be aware of the problems with caries diagnosis on a radiograph familiarity with guidance relating to recall intervals for radiographs of caries diagnosis
what is caries
a multifactorial disease
infectious disease
how does caries happen
due to lactic acid being produced by bacteria whilst fermenting sugars
it is a process of demineralisation and remineralisation
which bacteria can cause caries
Strep mutans
what is included in millers triad
susceptible tooth surface* sugars* time bacteria* * involved in the venn diagram
how can caries be classified
anatomical sites
activity
where can caries occur on anatomical sites
pit/fissure smooth surface enamel root primary secondary/recurrant residual
how can caries be classified by activity
arrested active which can include: rampant bottle/nursing early childhood
what are the levels of disease
D1
D2
D3
D4
if someone has a disease of D1 what does that mean
white/opaque or brown lesion but surface hard and occlusal surface hard on probing
if someone has a disease of D2 what does that mean
slight loss of surface
sticky fissures but NO dentine involvement
if someone has a disease of D3 what does that mean
dentine involvement but NO pulp involvement
if someone has a disease of D4 what does that mean
possible or definite pulpal involvement
how are stages D1 and D2 managed
usually by preventative stages
how will we manage stages D3 and D4
restorative measures
where does caries move faster
in the dentine rather than enamel
why does the caries move faster in the dentine
due to the porous nature of the dentine
what do we need to consider when diagnosing and detecting
activity of the caries and the presence of it
how can we detect caries
visual radiography temporary tooth separation fiberoptic transillumination laser fluorescence electrical conductance measurements research techniques eg MRI
How long does an MRI take
around 30 mins
advantages for using MRI to detect caries
no ionising radiation
disadvantages for using MRI to detect caries
very long exam
specialist equipment
difficult with children
how do we use temporary tooth separation
USING RUBBER orthodontic bands which can separate contact points allows us to visually see caries but also on the radiograph reduces enamel overlap
how does fibreoptic transillumination work
a white light on a very fine probe (0.5mm diameter) between a contact point therefore can detect inter proximal caries
what is shown when we have a sound tooth surface with fiberoptic transillumination
a sound colour all the way through
what is shown when we have a carious tooth surface with fiberoptic transillumination
the light will stop as there is no longer a smooth surface and there will be shadowing on the tooth surface
what does fluorescence change with
changes with density
dentine fluoresces more than enamel
and caries more than that
what are the ways we can use radiographs for detecting caries
bitewings-primary
periapicals
why is bitewings the primary way of testing for caries
it shows the occlusal surfaces of posterior teeth
inter proximal surfaces
and the crowns of posterior teeth
these are the areas to diagnose clinically
how do we carry out a bitewing
single film in the holder
patient bites on the bite block
and get an image of both the crowns
describe bitewing radiographs
the gold standard
gives the lowest dose for radiation for the max coverage of at risk areas
from mesial of first premolar to distal contact point
reproducible technique
how many bitewings may we require in adults
maybe two
how much thickness of enamel is acceptable in overlap on a radiograph
upto half of the thickness of enamel
periapical description
similar resolution to bitewings
but fewer crowns shown with similar x ray dosage
oblique lateral description
extraoral radiograph with lower resolution than bitewing
useful for caries in children
panoramic description
not INDICATED purely for caries diagnosis unless unable to tolerate intraorals
extraoral therefore lower resolution
moving x ray source and image detector
what are extra oral bitewings
uses the technique of panoramic but the film image is more similar to bitewings
advantages of extra oral bitewings
more comfortable for patients
better inter proximal separation between contact points than a panoramic
50% dose reduction than a panoramic
disadvantages of extra oral bitewings(compared with intraoral
higher dose
lower resolution
increased artefact
less reproducible
justifications of radiographs
show mineral loss ( 40% minimum) through the decreased density of hard tissue
reveals lesions otherwise which might be missed by visual examination:
pre cavitation
approximal surfaces
but early caries are hard to see
why does caries show darker on a radiograph
demineralisation of dentine/enamel
decerase in density
decrease of attenuation of x ray photons
area becomes more radiolucent( darker)
where are occlusal caries found
found in pits and fissures
when reaches the dentine appears to spread laterally- seen as triangular on a radiograph
where are interproximal caries found
on the mesial and vital surfaces
early lesions may involve enamel only
spreads laterally when it is in the dentine
what do we need to see low contrast lesions
good quality images
separation of contact points
how do we see buccal and lingual surface caries
can be seen in fissures
When small lesions are usually round becoming more elliptic or semilunar when large
do not widen to the occlusal surface
root surface caries
areas of recession in perio disease- involve cementum and dentine
root exposed- associated with recession
at the cervical margin but can be the root surface
what do we need to be aware of when looking for coot caries
cervical burnout artefacts
what is another name for secondary caries s
recurrent caries
where does recurrent caries occur
occurs adjacently near existing restoration
how do we report caries
systematic approach UR-UL-LL-LR
issues with radiographs
ionising radiation eg cancer
technique errors such as geometry and faulty processing
overlapping enamel can cause us to miss early lesions
how to we want to position the film
parallel to the contact point of the teeth and we want the film to be perpendicular and we need to position the ring as close as possible therefore lower magnification
what can be the issue with projection
a superficial lesion can be projected deeper e.g. an enamel lesion can appear to be into dentine due to BEAM ANGULATION SHIFT
why is it difficult to detect recurrent caries in a restored dentition
can be concealed by the restorations
what can mimic caries
cervical burn out
mach effect
corrosion
describe cervical burnout artefacts
can mimic root caries
occurs due to x rays over penetrating or burning out the thinner tooth enamel
Usually inner edge is more diffuse and rounded than caries
• Bounded by enamel superiorly and alveolar bone inferiorly.
what is the mach band effect
visual illusion
when uniform dark area meets uniform light area- the dark shade is even darker and the light is even lighter
clinically what can we see in the mach band effect
mask the enamel and the mach band will disappear
describe corrosion products
Radiolucency deep to amalgam restoration
Deposits of heavy metal ions leech into dentine e.g. tin, zinc in softened dentine.
when do we image
Importance of early caries detection
Image shows current state of demineralization
Decline in caries prevalence in recent decades
what do we need to consider in early caries detection
preventive management
or restorative management
issues with showing only the current state of demineralisation
patient might be in a phase of remineralisation or demineralisation due to change in diet
cannot tell the difference between active or arrested
high risk group benefits for radiographs
Benefit of radiographs over clinical diagnosis is 167%-800% compared to just visual exam
moderate risk group benefits
Benefit is 150%-270%
low risk caries group benefits
diagnostic yield but still significant 2-3x more carious lesions and 1.6%-25% clinically sound surfaces have caries on radiographs
what is the FGDP
faculty of general dental practice
what is the FGDP selection criteria for high risk
Posterior bitewings at 6 monthly intervals until no new or active lesions or patient changes into different risk category
what is the FGDP selection criteria for moderate risk
Annual posterior bitewings
unless risk status alters
what is the FGDP selection criteria for low risk
Posterior bitewings at 12-18 monthly intervals in primary dentition
– 2 year intervals in permanent dentition
what should be the key thoughts when taking an x ray
has it been done before
is it needed now
is it the best investigation
are they all needed
