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**Digital versus Conventional Workflow in Oral Rehabilitations: Current Status**  
**[PERSON]**  
Department of Dental Surgery, Faculty of Dental Surgery, University of Malta, MSD 2090 Misida, Malta;  
[EMAIL_ADDRESS]  
In recent years, computer-aided design and computer-aided manufacturing (CAD-CAM) technology has developed along with its applications in dentistry, including several new techniques that are used in oral rehabilitation applications [1, 2, 3, 4, 5, 6, 7, 8]. These techniques usually differ from conventional analog techniques regarding the way in which impressions are obtained (e.g., conventional impressions vs. intraoral scanning) or the way restorations are designed and produced (e.g., conventional waxing and casting vs. CAD-CAM). The general advantages that digital workflow involving CAD-CAM has over conventional workflow include faster treatment times, shorter appointments, reduced patient discomfort, no need to use plaster models and better predictability [9, 10]. Another key feature of digital workflow is the ability to merge and superimpose three-dimensional (3D) meshes from different imaging examinations to create a virtual patient, which enhances virtual treatment planning and communication with patients [11]. The general disadvantages of digital workflow that have been described include purchasing and managing costs, as well as a learning curve [9]. Nevertheless, it is also important to understand differences in quantitative outcomes such as trueness and precision between digital and conventional workflows. One of the most commonly investigated quantitative comparisons in digital dentistry is between conventional impressions and intraoral scans. In comparison to conventional impressions, intraoral scanning (IOS) has been considered to be more accurate in regard to the outcomes of resulting CAD-CAM crowns and short-span fixed partial dentures [12, 13, 14]. Several articles have found marginal gap values lower than 60 \(\upmu\)m for CAD-CAM dental crowns produced using IOS, whereas gap values up to 183 \(\upmu\)m were found for crowns produced using conventional impressions [12]. One finding that is found across multiple studies is that ensuring the accuracy of intraoral scans of long-span and completely dentulous arches it is still challenging [15]. Conventional impressions can also be digitalized to enable the execution of digital workflows by using CBCT or desktop optical scanners. The latter, however, has been found to offer significantly lower gaps for CAD-CAM crowns (reported to be around 50-60 \(\upmu\)m), as compared to the former (reported to be higher than 100 \(\upmu\)m) [16, 17, 18]. The acquisition parameters of CBCT also seem to have an influence on the results, as one study found that a voxel size of 0.125 mm led to better results in comparison to other values [16]. In addition to the differences between conventional and digital impressions, CAD studies have also focused on assessing and comparing different software programs and methods for use in the digital design of dental prosthesis [19, 20]. Virtual waxing was found to be affected not only by subgingival finish lines of the scanned preparations and the IOS device used [19], but also by the operator's clinical experience and educational background, as prosthodontists with basic CAD training were shown to outperform dental professionals who had CAD certificates but less clinical experience [20]. In terms of production, studies assessing conventional and CAD-CAM methods in the manufacture of dental prosthesis have compared CAD-CAM with pressed ceramic restorations [21, 22, 23, 24, 25]. While for dental crowns, CAD-CAM was found to have significantly better adaptation than pressed ceramics [21, 22], most of the studies concerning laminate veneers found a different pattern, with similar [23; 24] or worse adaptation using CAD-CAM [25].