In a bitewing radiograph, how do you distinguish caries, restorations, and structural defects?

• A. Identify margins and radiolucencies, compare with prior images, assess restoration boundaries, differentiate artifacts from pathology, correlate with clinical exam
• B. Rely only on color
• C. Ignore restorations
• D. Assume all radiolucencies are caries

Answer: (B)

Interpreting bitewing radiographs hinges on pattern recognition of radiodensity, margins, and how features align with tooth anatomy, plus clinical context. Caries show up as radiolucent areas at or between teeth, often starting at the contact point and extending into dentin with irregular or wedge-shaped borders; their appearance reflects demineralization rather than a change in color, so you assess progression over time and by how the lesion communicates with the adjacent enamel and dentin. Restorations appear as radiopaque regions with well-defined margins; the exact look depends on the material—amalgam tends to be very bright and uniform, while composites and other restoratives have variable radiopacity and distinct interfaces with the tooth. Structural defects, like cracks or structural fractures, present as radiolucent lines that may traverse enamel and dentin and can extend through restorations; these lines often have a linear appearance and may correlate with signs of tooth flexure or fracture patterns in the clinical exam. To avoid misinterpretation, compare current images with prior radiographs to judge whether a lesion is new or evolving, differentiate true pathology from artifacts (which can mimic lesions) by checking consistency with adjacent structures and patient bite, and always corroborate radiographic findings with a thorough clinical examination. Relying on color isn’t helpful here because bitewing radiographs are grayscale, so diagnostic information comes from density patterns, borders, and context rather than color.