The perception of the seriousness of a false-negative or false-positive diagnosis could influence treatment decision making for carious lesions. In order to investigate this hypothesis, the perceived risk of a complaint at a disciplinary tribunal was used as an indicator of the seriousness of the consequences of treatment decision errors. Using a computer programme for caries diagnosis on radiographs and by means of a questionnaire, was investigated in a group of fourth-year dental students whether their accuracy of treatment decision making for carious lesions was dependent on the perception of the risk of a complaint at a disciplinary tribunal. The perception of the likelihood of complaints does not seem to play a significant role in the accuracy of decision making. However, the students demonstrated unrealistical high risk perceptions of a complaint at a disciplinary tribunal following a treatment decision making error by a false diagnosis of a carious lesion on a bitewing radiograph.