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Radiographic Caries Identification
developed by Dr. Joen Iannucci Haring DDS, MS

INTRODUCTION

Although many carious lesions are easily seen clinically or radiographically, others may be very difficult to identify. Studies have indicated that there are significant variations among dental professionals regarding the radiographic interpretation of dental caries.

In order to detect dental caries, both careful clinical and radiographic examinations are necessary. The focus of this web resource is RADIOGRAPHIC CARIES IDENTIFICATION and includes the following information:

CARIES DETECTION
RADIOGRAPHIC CLASSIFICATION OF CARIES
INTERPRETATION TIPS
FACTORS INFLUENCING CARIES INTERPRETATION
CONDITIONS RESEMBLING CARIES

Following these introductory topics, there is an opportunity to view radiographs and test your skill in identifying dental caries.

C A R I E S D E T E C T I O N

A dental examination for caries cannot be considered complete without radiographs. The dental radiograph enables the dental professional not only to evaluate the extent and severity of a carious lesion seen clinically, but also to identify carious lesions that are not visible clinically. In order to establish a diagnosis and develop treatment decisions, information is needed from the clinical examination, radiographic examination and patient history.

CLINICAL EXAMINATION

All teeth must be examined clinically for dental caries. The dental professional should have a set sequence for the caries examination. The examination should begin with tooth #1, followed by tooth #2, #3, etc., and end with tooth #32. All exposed and accessible surfaces should be examined for dental caries. All positive and suspicious clinical findings should be documented in the patient record and evaluated with dental radiographs.
In order to ensure good visibility, a bright operatory light should be used in the clinical examination. A mirror and explorer can be used to examine the teeth for evidence of dental caries. The mirror can be used to reflect light, to allow for indirect vision and to retract the tongue. The explorer can be used judiciously as a tactile device to detect the presence of any consistency changes (e.g., catches or tug-back) in the pits, fissures and grooves of the teeth as well as cavitation or break in the enamel of smooth surface lesions.
Compressed air can be used to dry teeth and remove debris in order to allow for a better visual examination. A small flashlight can be used to detect dental caries on anterior teeth. Trans-illumination, or the passage of light through the tooth, allows the clinician to determine if the enamel is healthy. When the anterior teeth are illuminated with light, healthy areas of enamel permit the passage of the light while areas involved with dental caries do not.
Clinically, a number of color changes may be seen with dental caries. Occlusal surfaces may exhibit dark staining in the fissures, pits and grooves, or exhibit a gross, or obvious, cavitation. Smooth tooth surfaces may exhibit a chalky white spot or opacity indicating demineralization. A clinician must examine these areas carefully to determine whether stained areas are also cavitated. An interproximal ridge overlying a carious lesion may also appear discolored. A radiograph of any suspicious area that exhibits a change in consistency or color can give the practitioner additional information concerning the extent and severity of the lesion present. In some instances, no color change, cavitation or consistency changes are noted clinically. It is in these cases that radiographs play such an important role in the identification of dental caries.

RADIOGRAPHIC EXAMINATION

Radiographs are useful in the detection of caries because of the nature of the disease process. Demineralization and destruction of hard tooth structures result in a loss of tooth density in the area of the lesion. The decreased density allows a greater penetration of x-rays in the carious area, and as a result, the carious lesion appears as a radiolucency on a dental radiograph (see red arrows). Radiolucent structures permit the passage of the x-ray beam and appear dark or black on a dental radiograph.

The degree of radiolucency seen on a dental radiograph is determined by the extent and severity of the destruction seen as a result of the caries process.

Caries is always farther advanced clinically than what is seen on a dental radiograph. The early changes associated with demineralization do not affect the density of the tooth, and consequently, an increased penetration of the x-ray beam is not seen.

The bite-wing radiograph, a radiograph that shows the crowns of both the upper and lower teeth on the same film, is the radiograph of choice for the evaluation of dental caries. A periapical radiograph utilizing the paralleling technique can also be used to detect interproximal caries. In order for a bite-wing radiograph to be considered diagnostic for the evaluation of dental caries, the following criteria should be met:

DIAGNOSTIC BITE-WING CRITERIA

Exposure and processing: Proper film exposure and processing techniques must be used.
Open contacts: Interproximal areas must demonstrate open contacts; a thin radiolucent line should be seen between the contacts of adjacent teeth (see red arrows on film above).
Occlusal plane: The occlusal plane should be positioned horizontally along the midline of the long axis of the film.
Premolar placement: The premolar bite-wing should demonstrate the distal contact areas of both the maxillary and mandibular canines.
Molar placement: The molar bite-wing should be centered over the second molar.
Errors: The bite-wing should be free of technique errors (e.g., cone cuts, film bending and backwards placement of a film).