Materials and Method: Thirty (30) dentistry students in their fourth year were randomly selected for the execution of a full mouth periapical examination of the mandible and the maxilla, when performed on a mannequin.

Result: There was a greater frequency of radiographic technique errors with the use of the sensor than with the phosphor plate. Among the errors observed, the highest frequency was the absence of a safety margin for the sensor (35.7%), while for the phosphor plate, it was an overlapping of the proximal faces (23.1%). When using both of the systems, the region of the lower right premolars presented the highest percentage of errors. With the use of the phosphor plate, 7.61% of the images were repeated, with a maximum of 2 replicates in 4 radiographs. While with the sensor, 38.57% needed to be repeated and 4 of these were repeated 9 times. McNemar test revealed statistically significant differences for the errors of a poor centering, an excessive safety margin and a non-parallel safety margin, between the images taken with the phosphor plate and with the sensor.

Conclusion: The greatest number of errors and repetitions occurred with the use of the digital sensor. This has emphasized the need for a greater training of the dentistry students with these systems, in order to reduce the radiation exposures and to protect the patients.