摘要： Introduction: This study evaluated 4 different light-emitting diode (LED) transilluminators and the impact of operator experience in the detection of dentinal defects through an ex vivo TRUEJAW surgical model (Dental Engineering Laboratories, Santa Barbara, CA). Methods: Forty-four extracted and endodontically treated mandibular premolar teeth were evaluated. Teeth were mounted in the models followed by surgical ?aps and osteotomies to expose the apical third of the roots. After apical resection, the root-end surfaces were randomly inspected for the presence or absence of dentinal defects using a dental operating microscope (DOM) at !19.4 magni?cation by experienced and novice LED evaluators. The assessment was made with the DOM light and 4 masked LED transilluminators of different diameters and luminous ?ux. The teeth were examined outside the models to establish the ground truth. The sensitivity, speci?city, and kappa and McNemar test values of each light source by examiner were calculated. Results: The use of LED transilluminators improved the diagnostic sensitivity of dentinal defects when compared with the DOM light alone for both examiners. For the LED-experienced evaluator, the medium-low transilluminator had statistically signi?cant higher sensitivity than the DOM light and the small-low and small-high transilluminators (P , .05). For the novice LED evaluator, the medium-high transilluminator had the highest sensitivity. There was a statistically signi?cant difference between the sensitivities of the medium-low transilluminator between the examiners (P , .05). Conclusions: Within the limitations of this ex vivo surgical study, dentinal defects were more often detected with the LED transilluminators with a larger diameter and increased lumens. The operator’s LED transilluminator experience was found to have a positive effect on the detection of dentinal defects using transillumination.