## 5 Discussion  
There are several clinical advantages in integrating RE and CAD/CAM systems into the daily orthodontic workflow that go beyond the general assumption of reduced costs and efficient production and deal with enhancing the quality standard of the treatment provided to orthodontic patients. The descriptions provided in the present paper represent some of the main applications of RE and digital systems that can describe the advancement of the orthodontic discipline. The first claimed advantage is related to the diagnostic stage. RE and digital systems allow for a complete 3D analysis of the craniofacial complex, possibly integrating data from CBCT, IOS, and FS. Figure 7 showed how 3D data can provide useful information for diagnostic and treatment plans; however, should 3D data always replace 2D information for orthodontic purposes? A recent well-conducted study [58] compared the diagnostic agreement between a 2D conventional diagnostic package (intra-oral photograph, extra-oral photograph, cephalogram) and a 3D dataset (IOS and photogrammetry integrated). The authors found a fair agreement within and between the method involving cephalometric radiographs and the method involving 3D dentofacial photogrammetry and an excellent agreement for important treatment planning decisions (extraction and orthographic surgery). Clinicians could interpret these findings in two different ways: (1) 3D systems are relatively accurate, and by integrating intra-oral and facial data, it is possible to make an appropriate diagnosis, underestimating the role of cephalogram, as also suggested by previous evidence, although the cephalogram is still an important diagnostic tool for assessing growth pattern and bone availability in the anterior region [59]; and (2) on the contrary, since no diagnostic differences were found between 2D and 3D datasets, 3D intra-oral and facial data do not introduce new useful diagnostic information. As a consequence, the choice of registering intra-oral and facial scan data should be based on other advantages such as data storage and efficiency of visualization of integrated data rather than for improving the diagnostic process [60]. These findings underline the importance of clinical judgment, which still represents the pillar of the diagnostic process in orthodontics. The second claimed advantage is related to the treatment plan stage. RE and digital systems represent extraordinary tools for the customization of orthodontic treatment. The possibility of simulating a virtual patient represents an important step towards a personalized diagnostic and therapeutic approach [61]. From the virtual planning of miniscrewinsertions to digital orthodontic setups, clinicians can plan the clinical procedure within a virtual environment, analyzing all the variables that may interfere with its predictability. For example, with digitally assisted miniscrew insertion systems, clinicians can evaluate a priori the quantitative and qualitative bone characteristics, soft-tissue-miniscrews contact, and specific anatomical condition to optimize the stability of the miniscrew under orthodontic and orthopedic loads. Besides the patient-oriented benefits of clear aligners system such as the aesthetic solution and comfort of the orthodontic treatment, the actual worth of RE in this orthodontic treatment option is to orient clinicians toward a proactive approach which means to look at the treatment resolution with the outcomes in mind. Using this approach, the orthodontist must program the biomechanical strategy and all the biomechanical steps before starting the treatment, including deciding which auxiliaries and/or attachments should be used and at which steps. The rate of tooth movement may also be adjusted according to the individual's bone physiology by altering the scheduled number of days for aligner changes depending on the individual's response to tooth movement.