Dental Caries and Radiology

Caries Detection and Radiology

• Correct positioning of the image receptor is crucial to visualize proximal surfaces clearly.
• Caries lesions cause demineralization of enamel and dentin, resulting in radiolucent (dark) regions on images.
• Panoramic images have poor resolution and should not be relied upon to detect caries.

Radiolucent Regions

• Radiolucent regions on images may not necessarily represent active carious lesions, but can be older, inactive (arrested) lesions or "scars" in the enamel.
• Minerals from saliva can remineralize the outermost surface of the tooth, but not deeper tissues.

Extraoral Bitewing Images

• Extraoral bitewing images can be used when intraoral images are impossible to obtain, such as with uncooperative patients or those with anatomic constraints.

Caries Lesion Progression

• Caries lesions progress slowly, especially in enamel, and require individualized approaches to each patient.
• Imaging examinations are necessary to understand factors contributing to disease.

Enamel Caries Lesions

• Enamel rods are oriented at 90 degrees to the surface, resulting in demineralization along the long axes of the enamel rods.
• Classic shape of an enamel caries lesion is a triangle with its broad base on the proximal surface and its tip pointing toward the dentinoenamel junction (DEJ).

Interproximal Carious Lesions

• Interproximal carious lesions are commonly found between contact points of teeth, extending apically to near the free gingival margin.
• A small amount of demineralization on the middle of the proximal surface may not be visible radiographically.

False-Positive Interpretations

• There is no 100% agreement on caries diagnosis between different observers, especially with enamel caries.

Dental Caries Disease Mechanism

• Lactic acid produced by S. mutans in the bacterial biofilm reduces local pH and causes demineralization of tooth structure.
• Demineralization process begins beneath the enamel surface, leaving behind a thin, mineralized, intact surface layer.

Caries Appearance

• Early, active lesions appear as white, chalky spots, whereas older, arrested lesions appear darker (black or brown).
• Intraoral bitewing images are the preferred images to detect interproximal caries in posterior teeth.