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IMPORTANT NOTES:  This web resource is a review of the radiographic interpretation of dental caries ONLY; this resource does not provide definitive instruction in clinical dental caries diagnosis or the restorative treatment planning options. 

This resource on radiographic interpretation of dental caries and corresponding terminology is consistent with that presented in the recommended text for Oral Radiology DENT 645, Oral Radiology:  Principles and Interpretation, 4th edition, by White and Pharoah (2000).

For terminology and information concerning the clinical diagnosis of dental caries (which may be slightly different from the radiographic terms) and restorative treatment planning options, please refer to materials presented in the Operative Dentistry courses, and the recommended text Sturdevant's Art & Science of Operative Dentistry, 4th edition (2002).  Please note - the terminology used to describe the location, extent and rate of caries activity in Sturdevant's Art & Science of Operative Dentistry is not reviewed in this web resource. Again, this web resource and instructional exercises refer ONLY to the radiographic identification of caries.

The radiographic appearance of dental caries can be classified according to the location of the caries on the tooth.  Caries involving the interproximal, occlusal, buccal, lingual and root surfaces may all be seen on a dental radiograph.  In addition, recurrent and rampant caries may also be viewed on dental radiographs.
INTERPROXIMAL CARIES

The term interproximal means between two adjacent surfaces.  Caries found on the smooth surfaces between two teeth is termed interproximal caries.   On a dental radiograph, interproximal caries is typically seen at or just below (apical to) the contact point.  This area is difficult, if not impossible, to examine clinically with an explorer.

As caries progresses inward through the enamel of the tooth, it assumes a triangular configuration; the apex (or point) of the triangle is seen at the dentino-enamel junction (DEJ).  As caries reaches the DEJ, it spreads laterally and continues into dentin.   Another triangular configuration is seen in dentin, this time the base of the triangle is found along the DEJ and the apex is pointed toward the pulp chamber.

Interproximal caries viewed on a dental radiograph can be classified according to the depth of penetration the lesion exhibits through the enamel and dentin.   Interproximal carious lesions viewed on a dental radiograph can be classified as incipient, moderate, advanced and severe.
Incipient
Interproximal Caries		 diagram_incipient.jpg (38487 bytes)

An incipient interproximal lesion extends less than halfway through the thickness of enamel.  The term incipient means beginning to exist or appear. An incipient lesion is seen in enamel only.
Moderate
Interproximal Caries		 diagram_moderate.jpg (47679 bytes) A moderate interproximal lesion extends greater than halfway through the thickness of enamel, but does not involve the DEJ.  A moderate lesion is seen in enamel only.
Advanced
Interproximal Caries		 diagram_advanced.jpg (48644 bytes) An advanced interproximal lesion extends to the DEJ or through the DEJ and into the dentin, but does not extend through the dentin greater than half the distance toward the pulp.  An advanced lesion affects both enamel and dentin.
Severe
Interproximal Caries		 diagram_severe.jpg (45889 bytes) A severe interproximal lesion extends through enamel, through the dentin and greater than half the distance towards the pulp.  A severe lesion involves both the enamel and dentin and may clinically appear as a cavitation (or hole) in the tooth.
OCCLUSAL CARIES
The term occlusal refers to the chewing surfaces of the teeth.   Caries that involves the pit and fissure surfaces of the posterior teeth is termed occlusal caries.  A thorough clinical examination is the method of choice for the detection of occlusal caries.  Because of the superimposition of the dense buccal and lingual enamel cusps, early occlusal caries is difficult to see on a dental radiograph; consequently, occlusal caries is not seen on a radiograph until there is involvement of the DEJ. 

Occlusal carious lesions can be classified as incipient, moderate and severe.

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Incipient
Occlusal Caries

Incipient occlusal caries cannot be seen on a dental radiograph and must be detected clinically with an explorer instead.
Moderate
Occlusal Caries

Moderate occlusal caries extends into dentin and is seen as a very thin radiolucent line.  The radiolucency is located under the enamel of the occlusal surface of the tooth.  Little if any radiographic change is noted in the enamel.
Severe
Occlusal Caries

Severe occlusal caries extends into dentin and is seen as a large radiolucency.  The radiolucency extends under the enamel of the occlusal surface of the tooth.  Severe occlusal caries is apparent clinically and appears as a cavitation (or hole) in a tooth.
BUCCAL AND LINGUAL CARIES
As the names suggest, buccal caries involves the buccal tooth surface, while lingual caries involves the lingual tooth surface.  Because of the superimposition of the densities of normal tooth structure, buccal and lingual caries is difficult to detect on a dental radiograph and instead, is best detected clinically.

When viewed on a dental radiograph, caries that involves the buccal or lingual smooth surfaces appears as a small, circular radiolucency.  In order to determine the location of the lesion, a clinical examination with an explorer is necessary.

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ROOT SURFACE CARIES

Root surface caries only involves the roots of teeth.  The cementum and dentin located just below the cervical region of the tooth is involved.  No involvement of enamel is seen.  Bone loss and corresponding gingival recession precede the caries process and result in exposed root surfaces.

Clinically, root surface caries is easily detected on exposed root surfaces.  The most common locations include the exposed roots of the mandibular premolar and molar areas. 

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On a dental radiograph, root surface caries appears as a cupped-out or crater-shaped radiolucency just below the cemento-enamel juction (CEJ).  Early lesions may be difficult to detect on a dental radiograph.
RECURRENT CARIES
Secondary or recurrent caries occurs adjacent to a pre-existing restoration.  Caries occurs in this region because of inadequate cavity preparation, defective margins or incomplete removal of caries prior to the placement of the restoration.
High caries incidence and poor oral hygiene also play a part. 

On a dental radiograph, recurrent caries appears as a radiolucent area just beneath a restoration.  Recurrent caries is most often seen beneath the interproximal margins of a restoration.

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RAMPANT CARIES
The term rampant means growing or spreading unchecked.   Rampant caries is advanced and severe caries which affects numerous teeth in the dentition.  Rampant caries is typically seen in children with poor dietary habits or in adults with a decreased salivary flow.

Radiation caries - rampant caries resulting from xerostomia caused by head and neck radiation therapy.

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