This study compared the efficiency of unaided visual examination, intraoral camera and operating microscope according to a visual scoring system (ERK) at occlusal caries detection. A total of 84 extracted human molars were mounted to create mouth models with a premolar in contact on both sides. The models were examined in a phantom head simulating clinical conditions by four observers using the three techniques: unaided visual examination, an intraoral camera and on operating microscope according to the ERK scale. The teeth were than sectioned in a mesio-distal direction and examined under a stereomicroscope with 10x magnification for histological validation. The sensitivity, specificity, positive predictive and negative predictive values were calculated for the four observers with three techniques and statistical analyses were performed using Friedman and DUNN tests, while strength of agreement was determined by calculating Kappa values. From the data, mean sensitivity values were cal. culated as 0.26, 0.43, 0.49 and mean specificity values as 0.87, 0.80 and 0.73 for unaided visual examination, intraoral camera and operating micro scope, respectively. The Kappa values ranged between 0.187 and 0.301 for visual examination, 0.328 and 0.459 for intraoral camera and 0.363 and 0.516 for operating microscope. As a result, the use of an intraoral camera and operating microscope improved occlusal caries detection according to the ERK scale.