Radiology of Caries
Radiology of Dental Caries
ODM 820 spring 2009, May 19 2009
August 2002
August 2005
Radiology of Dental Caries
Introduction
Dental caries is a multifactorial disease with interactions
among three factors: the tooth, the microflora, and the
diet
Caries is an infectious disease since it is the lactic acid
produced by bacteria from the fermentation of the CH
that causes the demineralization of the dental hard tissues
The initial carious lesion is a subsurface loss of mineral
in the outer tooth surface. It appears clinically as a chalky
white or an opaque or dark, brownish spot
Radiology of Dental Caries
Use of Intraoral Radiographs
Radiography is useful for detecting dental caries because
the caries process causes demineralization of enamel and
dentin.
The lesion is seen in the radiographs as a radiolucent (dark)
zone since the demineralized area of the tooth do not absorb
as many x-ray photons as the unaffected portion.
The radiograph can not detect if the lesion is active or arrested
(unless you have different radiographs at different times and
you can see the progression of the lesion)
Radiology of Dental Caries
Use of Intraoral Radiographs
Radiography is a valuable supplement to a thorough clinical
examination of the teeth for detecting caries
However, even the most meticulous clinical examination may
fail to reveal demineralization beneath the surface, including
occlusal surfaces
Clinical access to proximal tooth surfaces in contact is limited
Several clinical studies have shown that a radiographic
examination can reveal carious lesions both in occlusal
And proximal surfaces that would otherwise remain undetected
Radiology of Dental Caries
Radiographic examination to detect caries
• The BW projection is the most useful radiographic examination for
detecting caries
• The use of a film holder with a beam-aiming device reduces the
number of overlapping contact points and improves image quality
• Periapical radiographs are useful primarily for detecting changes in the
periapical bone (use of paralleling technique increases the value of
this projection in detecting caries)
• Traditionally size 2 “adult” films are used for a BW examination from the
age of 7-8 years onward
Radiology of Dental Caries
Radiographic examination to detect caries
• In recent decades there has been a dramatic decline in the prevalence
of caries in all western countries. Accordingly, the interval between
examination should be customized for each individual patient and
based on the perceived caries activity and susceptibility.
• Radiographs used to detect carious lesions should be mounted in
frames with dark borders and interpreted using a magnifying glass.
Radiology of Dental Caries
Radiographic detection of lesions
-Proximal surfaces
•The shape of the early radiolucent lesion in the enamel is classically
a TRIANGLE with its broad base at the tooth surface, spreading
along the enamel rods, but OTHER appearances are common such
as a “band” or a “thin line”
• When the demineralization front reaches the dentino-enamel junction
(DEJ), it spreads along the junction, frequently forming the base of
a second TRIANGLE with apex directed towards the pulp chamber.
• A lesion of proximal surfaces MOST COMMONLY is found in the area
between the contact point and the free gingival margin. The fact that
the lesion does not start below the gingival margin helps distinguish
a carious lesion from cervical burnout
Radiology of Dental Caries
“apparently intact DEJ”
Radiology of Dental Caries
Radiographic detection of lesions
- Classification of the interproximal caries
• Incipient 
Extends less than halfway through the thickness of the
enamel (it is only in enamel !!)
• Moderate 
Extends greater than halfway through the thickness of the
enamel, but does not involve the DEJ
• Advanced  Extends to the DEJ and into the dentin, but does not
extends through the dentin greater than half the distance
towards the pulp
• Severe 
Extends through the enamel, dentin and greater than
half the distance towards the pulp
Radiology of Dental Caries
From Radiographic caries interpretation, Dr. Haring, OSU
cervical burnout
Incipient interproximal caries
Advanced interproximal caries
Advanced interproximal caries
Incipient interproximal caries
Where?
Radiology of Dental Caries
Radiographic detection of lesions
-Proximal surfaces
Cervical Burnout
Diffuse radiolucent areas with ill defined borders may be apparent
radiographically on the mesial or distal aspects of the teeth in the cervical
regions between the edge of the enamel cap and the crest of the alveolar
ridge  cervical burnout
This is caused by the normal configuration of the teeth which
results in decreased x-ray absorption in the mesial and distal
aspects of the teeth
cervical burnout
Radiology of Dental Caries
Radiographic detection of lesions
-Proximal surfaces
• Close attention should be paid to intact proximal surfaces adjacent to
a tooth surface with a restoration since occasionally this surface is
inadvertently damaged during the restorative procedure and is thus
at greater risk for caries
• The proximal surfaces of posterior teeth are often broad, the loss of
small amounts of mineral form incipient lesions and the advancing front
of active lesions are often difficult to detect in the radiograph.
• Lesions confined to enamel may not be evident radiographically until
approximately 30% to 40% demineralization has occurred
Radiology of Dental Caries
Radiographic detection of lesions
-Proximal surfaces
• Even experienced dentist often do not agree on the presence or
absence of caries examining the same set of radiographs, especially
when the lesions are limited to enamel.
• A lesions extending into the dentin in the radiograph may be easier
to detect with greater agreement among experienced observers
• Potentially, a progressing proximal lesions may be arrested if cavitation
has not developed. If cavitation has occurred, the lesions will always be
active since the bacteria that colonize within the cavity cannot be
removed.
Radiology of Dental Caries
Radiographic detection of lesions
-Proximal surfaces
Experience !!
Caries
Detection
5 years of
practice
Years
Radiology of Dental Caries
Radiographic detection of lesions
-Occlusal Surfaces
• Carious lesions in children and adolescents most often occur on
occlusal surfaces of posterior teeth.
• The demineralization process originates in enamel pits and fissures,
where bacteria plaque can gather.
• The lesion spreads along the enamel rods and, if undisturbed, penetrates
to the DEJ, where it may be seen as a thin radiolucent line between
the enamel and the dentin.
• Occlusal lesions commonly start in the sides of a fissure wall rather than
at the base and then tend to penetrate nearly perpendicular towards the
DEJ
Radiology of Dental Caries
Radiographic detection of lesions
-Occlusal Surfaces
• When an occlusal lesion is confined to enamel, the surrounding enamel
often obscures the lesion. As the carious process progresses, a
radiolucent line extends along the DEJ. As the lesions extend into the
dentin, the margin between the carious lesion and non carious dentin is
diffuse.
• The classic radiographic appearance of occlusal caries extending into
the dentin is a broad-based, radiolucent zone, often beneath a fissure,
with little or no apparent changes in the enamel
Radiology of Dental Caries
Histological appearance of a carious lesion
Occlusal caries
occlusal
Radiology of Dental Caries
Radiographic detection of lesions
- Buccal and Lingual surfaces
• Buccal and lingual carious lesions often occur in enamel pits and
fissures of the teeth. When small, these lesions are usually round; as
they enlarge, they become elliptical or semi-lunar.
• It is difficult to differentiate between buccal and lingual caries on a
radiograph. When viewing buccal or lingual lesions, the clinician
should look for a uniform non-carious region of enamel surrounding
the apparent radiolucency.
• Clinical evaluation is the definitive method
Buccal caries
Radiology of Dental Caries
Radiographic detection of lesions
- Root surfaces
• Root surface lesions involve both cementum and dentin and are
associated with gingival recession. The exposed cementum is relatively
soft and usually only 20 to 50 µm thick near the CEJ, so it rapidly
degrades by attrition, abrasion, and erosion.
• Root surface caries should be detected clinically, and often radiographs
are not necessary.
• In proximal root surfaces radiographic examination may reveal lesions
that have gone undetected.
• Difficult to differentiate between cervical burnout and caries
Root Surface Caries
Radiology of Dental Caries
Radiographic detection of lesions
- Associated with dental restorations
• A carious lesion developing at the margin of an existing restoration
may be termed secondary or recurrent caries. It should be noted, though,
that a lesion developing in a restored surface is mot frequently a new
primary demineralization.
• These lesions should be treated like any new caries lesion.
• It is important not to confuse secondary caries with residual caries, which
is caries that remain if the original lesion is not completely removed.
• A lesion next to a restoration may be obscure by the radiopaque image
of the restoration  detection  careful examination !!!
Radiology of Dental Caries
Radiographic detection of lesions
- Associated with dental restorations
• Restorative materials vary in their radiographic appearance depending
on thickness, density, atomic number, and the x-ray beam energy used
to make the radiograph  some materials can be confused with caries:
calcium hydroxide is a good example
Enamel
caries
Recurrent caries
Cervical burnout
Recurrent Caries
Interproximal caries
Radiology of Dental Caries
Radiographic detection of lesions
Interpretation TIPS !! (You will need it)
• All films must be properly mounted
• Mounted films should be viewed in a room with subdue lighting that is
free of distractions
• An illuminator or viewbox is MANDATORY
• If the screen of the viewbox is not completely covered by the mounted
radiographs, the harsh light around mounted films must be masked to
reduce glare and intensify the detail and contrast of the radiograph
images
• Magnifier  mandatory
• Use multiples views of the same area
Radiology of Dental Caries
Radiographic detection of lesions
Factors influencing caries interpretation
• Errors in technique may result in non-diagnostic films. For example,
a BW that is used to detected dental caries must be free of overlapped
contacts. Improper horizontal angulation causes overlapped contact
areas and makes impossible to interpreted the interproximal regions
Overlapping contacts
Radiology of Dental Caries
Radiographic detection of lesions
Conditions resembling caries
Restorative materials
Composites, silicates and acrylics, may resemble caries
Careful examination helps to identify the well defined
smooth outlines of the preparation
Restorative materials
Radiology of Dental Caries
Radiographic detection of lesions
Conditions resembling caries
Abrasion
Abrasion refers to the wearing away of tooth structure from the friction with
an foreign object  for example tooth brushing
On radiographs, tooth abrasion appears as a well defined horizontal radiolucency
along the cervical region of a tooth
Radiology of Dental Caries
Radiographic detection of lesions
Conditions resembling caries
Again….
Cervical Burnout (IMPORTANT)
Cervical burnout appears as a collar or wedgeshaped radiolucency on the mesial and distal
root surfaces NEAR the CEJ of a tooth
May be confused with root caries  look at the
Alveolar bone level