Radiographic display of carious lesions and cavitation in approximal surfaces: Advantages and drawbacks of conventional and advanced modalities.

BACKGROUND: Treatment strategies have changed with efforts on arresting carious lesions suspected to have an intact surface sparing operative treatment for cavitated lesions. Radiography is still the most recommended adjunct method in the diagnosis of clinically inaccessible approximal surfaces. BITEWING RADIOGRAPHY: The major drawback of bitewing radiography for caries diagnosis is that the clinical state of the surface cannot be determined; i.e. if cavitation has developed or the demineralized surface is still intact. Based on studies of the relationship between radiographic lesion depth and clinical cavitation in approximal surfaces, a threshold for operative treatment decision has been suggested when a lesion is observed radiographically more than one-third into dentine. However, the results from previous studies are contradictory and the majority of studies are ~25 years old. In addition, there are few longitudinal observational studies on the behaviour of dentinal carious lesions, particularly in adults. CONE BEAM COMPUTED TOMOGRAPHY: Cone beam CT is an advanced 3-dimensional radiographic modality, which seems much more accurate than intra-oral modalities for displaying cavitation in approximal surfaces. Nonetheless, there are several drawbacks with CBCT, such as radiation dose, costs and imaging artefacts. Therefore, CBCT cannot be advocated at current as a primary radiographic examination with the aim of diagnosing cavitated carious lesions.
CONCLUSIONS: Bitewing radiography is, thus, still state-of-the-art as an adjunct in diagnosing carious lesions in clinically inaccessible approximal surfaces. The risk for cavitation is related to lesion depth, but new studies are needed in both child and adult populations to validate current thresholds for the operative treatment decision based on the radiographic lesion depth.