Radiographic diagnosis of caries Flashcards
What is caries?
Multifactorial, infectious disease. Lactic acid causes demineralisation and demineralisation may extend well into dentine before cavitation occurs.
How do we describe lesions?
Enamel, dentine, root, primary, secondary/recurrent, residual - demineralised tissue left behind when a filling is placed.
Active - progressing demineralisation
Early childhood - children under 6
Rampant - adolescents
Arrested/inactive - remineralisation process
How do we classify caries?
Class I: Pit or fissure
Class 2: Interproximal surface of posterior teeth
Class 3: Interproximal area of anterior teeth
Class 4: Interproximal area of anterior tooth involving incisal edge
Class 5: Lesion affecting cervical third of tooth
What is the pitts classification of caries?
D1: white/opaque/brown lesion: surface hard on probing
D2: slight loss of surface, sticky fissures, no dentine involvement
PREVENTATION FOR ABOVE
D3: Dentine involvement not pulp
D4: Possible or definite pulpal involvement
RESTORATIVE
What is fibreoptic transillumination?
White light shone into contact points through probe, normal tooth scatters light caries reduces spread of light so appears dark - observed clinically.
Best for detection of approximal caries
Restoration blocks spread of light
What is fluorescence?
Light of known wavelength scatters through material some waves are absorbed and some lose energy and are emitted as waves with longer wavelength.
Changes with density - caries has a low density so alters fluorescence.
What are bitewing radiographs?
Most useful as maximum coverage for the lowest dose
Should see mesial contact point of first premolar to the most distal contact point
In adults, may need two to see all contact points
What is the acceptable amount of enamel overlap on radiographs?
No or minimal overlap but up to half thickness of enamel acceptable
What is a periapical radiograph?
Shows fewer crowns but has similar dose to bitewing
What is an oblique lateral radiograph?
Extraoral image with lower resolution than bitewing but useful for non tolerating children
Are panoramic radiographs indicated for caries?
No but used if a patient cannot tolerate intraorals, but has a lower resolution and as it moves it is not as sensitive and can contain artifacts so not useful for diagnosis of caries.
What are the advantages of an extraoral bitewing in a panoramic machine?
More comfortable, better interproximal separation between contacts than a panoramic.
50% dose reduction
What are the disadvantages of an extraoral bitewing in a panoramic machine?
Higher dose than bitewing, lower resolution and less reproducible.
How much mineral loss has to happen before a radiograph can detect it?
40%
What are the benefits of taking a radiograph?
Can reveal undetectable lesions by clinical exam - pre cavitation and approximal surfaces.
What does caries cause?
Demineralisation of inorganic portion and destruction organic portion.
How do we detect caries on a radiograph?
Causes a decrease in density which causes a decrease in attenuation of X-ray photons so the area becomes more radiolucent (darker).
How is occlusal caries identified on a radiograph?
As a triangular shape
What are approximal lesions and how to detect them on a radiograph?
Mesial and distal, early lesions may only involve enamel then spread laterally into dentine.
Need good quality to separate contact points and low contrast lesions.
What are buccal and lingual lesions?
Can arise in pits and fissures, when they are small they are round and when large become eliptic/semi lunar.
Do not widen to occlusal surface
How are root surface caries detected?
Clinically usually, lesions involve cementum associated with gingival recession.
Cervical burnout can mimic root surface caries
How do we report caries?
Systematically, assess each tooth from upper right to upper left to lower left finishing with lower right.
Assess for crowns, enamel and dentine density
Cervical margins
Existing restorations
Pulp chamber - reactive dentine and dentine involvement
What are the difficulties in radiographs?
Use of ionising radiation, technique issues and caries mimics
What is deterministic - direct effect of X rays?
Skin erythema
What is stochastic - random effect of X rays?
Cancer
What are technique issues?
Film faults, beam angulation, overlapping contacts obscuring lesions and superimposition of restorations.
What are film fault errors?
Positioning so contact points aren’t covered
Incorrect exposure - too dark or pale
Processing errors - streak artefact/splash can hide lesion
View with a correct orientation
Why may overlapping contacts occur?
Beam angulation may not be perpendicular to the film
What can make a superficial lesion look deeper?
Projection
Why can’t we localise buccal or lingual lesions?
They look the same, and cannot assess bucco lingual depth.
What is cervical burnout?
Cervical burnout appears as a radiolucent band around the necks of teeth and is more pronounced at the proximal edges. The X-ray photons overpenetrate or burn out the thinner tooth edge and create the radiolucent area that mimics cervical caries.
Inner edge more diffuse and rounded than caries
What is the mach band effect?
Dark area meets uniformly light area, dark shade appears even more darker and light lighter. Cover up enamel with hand and this band will disappear.
What are corrosion products?
Deposits of heavy metal ions (zinc tin) in softened dentine, can mimic caries.
When are radiographs indicated?
For seeing state of demineralisation. Using a second image to distinguish between active and arrested caries.
What are risk factors for caries?
Social, medical factors Use of fluoride OH Plaque control Saliva
What is the FGDP criteria for radiographs?
High risk - every 6 month bitewings until no new lesions or patient changes risk.
Mod - annual posterior bitewings
Low - 12-18 months in primary
2 years in permanent
