Efficacy of high-speed extraoral bitewing versus intraoral bitewing and panoramic for proximal caries in primary molars: A histological validation study.

INTRODUCTION: Detecting proximal caries in primary teeth is challenging. While intraoral bitewing radiography (IOBW) is the standard for proximal caries assessment, it faces limitations in pediatric patients. Extraoral bitewing radiography (EOBW) addresses these limitations by capturing bilateral posterior dentition within a single exposure. AIMS: The aim of the study was to evaluate the diagnostic efficacy of EOBW (high-speed [HS] and standard [SD] modes) in detecting proximal caries in primary molars compared to IOBW and panoramic radiography (PR), using histological examination as the reference standard. MATERIALS AND METHODS: Fifty-six extracted primary molars, with and without proximal dental caries, were randomly arranged in the 3D-printed skull and mandible. Four radiographic modalities were evaluated: IOBW using size #0 photostimulable phosphor plates, and EOBW-HS, EOBW-SD, and PR using a digital panoramic X-ray unit. Two observers independently graded caries twice at one-week intervals. Scores were compared with the histological reference standard. RESULTS: All modalities showed excellent intraobserver agreement (K > 0.8). For inter-observer agreement, all bitewing techniques demonstrated excellent agreement, whereas PR yielded the lowest. The Wilcoxon signed-rank test showed significant differences in caries grading scores between PR and all the other techniques. Area under the receiver operating characteristic curve indicated good diagnostic value for cavitated dentin caries across all modalities. EOBW demonstrated the highest sensitivity for detecting proximal caries in dentin. CONCLUSIONS: EOBW and IOBW provide comparable radiographic grading across all caries depths. EOBW-HS is an accurate alternative for detecting proximal dentin caries, particularly for pediatric patient's intolerant to intraoral radiography. However, caution should be exercised when enamel caries is suspected.