Moreover, another valuable and novel observation is the divergence seen in the importance of printed 3D models. For residents in oral surgery, printed 3D models caused more uncertainties and led to a decrease of diagnostic accuracy (if assessed in sequential order after OPG and CBCT). In contrast, residents in orthodontics seemed to benefit of an additional assessment of printed 3D models, which resulted in an improvement of their diagnostic ability. This increase in diagnostic accuracy might be partially explained with the larger experience residents in orthodontics share with model assessment.

All residents were asked whether the OPG contained sufficient information to enable a treatment. Interestingly, most residents in orthodontics and nearly all residents in oral surgery stated that the OPG did not provide sufficient information for a treatment plan (Fig. 3), even though the majority of the diagnoses were done correctly. Apparently, this dissonance indicates that diagnostic content cannot be equated with the required information needed for treatability. An accurate diagnosis is an essential part of treatment planning, but clinicians obviously look out for more than just a diagnosis when they evaluate and interpret an OPG. The observation that the treatability of the cases is viewed differently after CBCT assessment is in full agreement to previous studies [17, 24, 25].

Perhaps rather surprisingly, residents in orthodontics were significantly more often satisfied with the information given by an OPG for their treatment planning than residents in oral surgery who stated that the case was not treatable with the information provided by an OPG. This trend is probably due to the different goals pursued by each specialisation. The questions that the residents in orthodontics would like to have answered by any imaging modality will probably differ from the queries that the residents in oral surgery aims to have solved. Even when the one and same case is assessed by a resident in oral surgery and orthodontics, every one of them will be focused to answer different questions relating to treatability. Hence, it may be that an OPG will contain enough information for the resident in orthodontist to pen his treatment plan, but may hold only insufficient data for queries related to a surgical approach.