Severity-Dependent Modulation of Visual Attention Under Fatigue During Bitewing Radiograph Inspection: A Perceptual Eye-Tracking Experiment

Purpose: To examine whether visual fatigue following a full clinical day differentially affects visual attention to approximal carious lesions of varying severity on bitewing radiographs using eye-tracking methodology.Methods: In this two-group experimental eye-tracking study, 60 fifth-year dental students evaluated bitewing radiographs either before or after a full clinical day, a condition expected to induce visual fatigue. Subjective fatigue was assessed using a Visual Analog Scale (VAS). Four radiographs containing 15 approximal carious lesions classified according to the ICDAS criteria (E1–D3) were displayed for 30 seconds each. Predefined areas of interest (AOIs) were analyzed using fixation- and visit-based eye-tracking metrics, including fixation count, total fixation duration, and time to first fixation. Between-group comparisons were performed using independent-samples t-tests with Holm–Bonferroni correction.Results: VAS scores were significantly higher in the post-clinical group (p < 0.001), confirming greater subjective fatigue. For early-stage carious lesions (E1–E2), fatigued participants demonstrated significantly fewer fixations, shorter total fixation durations, and delayed time to first fixation. Comparable effects were observed for visit-based metrics. No significant differences were detected for advanced-stage carious lesions (D2–D3).Conclusion: Visual fatigue selectively modulates pre-decisional attentional allocation to early-stage approximal carious lesions while leaving engagement with advanced carious lesions largely stable. These findings underscore the vulnerability of low-salience radiographic findings under fatigue and highlight the value of eye tracking in understanding perceptual mechanisms in dental radiology.