## 5 Discussion  
The gradually increasing of the digitalization in dentistry has becoming an alternative to conventional approach. The study was aimed to evaluate the accuracy of scanned images of three intraoral scanners when scanning the dental surfaces in the presence and absence of artificial saliva. There are several in vitro and in vivo studies reporting clinically precision and trueness of contemporary IOS [6,13]. CEREC(r) Omnicam showed the lowest accuracy [9]. The study conducted by [PERSON] et al. [5] was aimed to compare the finish line distinctness (FLD), and finish line accuracy (FLA) of seven IOS (3M, CS 3500, and CS 3600, DWIO, Omnicam, PlanScan, and TRIOS), using a dental model with supra and subgingival margin placement of a preparation of the crown [7]. Their results no showed significant differences between all devices, but scanner dependent topography variations in TRIOS and 3M was found, reporting deviations below +/-25 \(\upmu\)m for TRIOS [5]. [PERSON] et al. stated that some of the examined IOS have shown a higher degree of accuracy of the finishing line compared to the conventional impression. They found TRIOS, CS 3600, and conventional impression shown deviations of less than 50 microns; CS 3500 deviations of 105 microns; dental wings intraoral scanners (DWIO), Omnicam, PlanScan, and 3M over 120 microns [12]. Different studies evaluating the marginal fit of metal ceramic crowns with the digital model are described in the literature, registering a value of \(\sim\)120 microns as the reference pattern for the measurement of variation of good accuracy [5, 6, 7, 8, 9]. [PERSON] et al. have compared the partial impression to conventional impression [7]. As a result of the performance, the authors described that the mean trueness of various IOS devices ranges between 20 and 48 \(\upmu\)m and the precision is between 4 and 16 \(\upmu\)m [17], as well as similar papers that have confirmed a clinical adaptability of the current available IOS devices for common practice, indicating a similar accuracy to conventional impression [6]. Another study registered mean deviations and averaged maximal positive and negative deviations of 17/\(-\)13 \(\pm\) 19 and 134/\(-\)123 \(\upmu\)m, respectively, for digitizing of a premolar and a molar with a chamfer preparation of a four-unit fixed dental prosthesis (FDP) [18]. A recent study evaluating the accuracy of FDPs, showed values of 30-68 \(\upmu\)m for the marginal inaccuracy and 29-88 \(\upmu\)m for the internal [19]. The measurement of deviations in'saliva samples' are 2-4 times higher than clinically acceptable cut-off value of 120 microns. These results clearly demonstrate that the scanned area must be saliva-free to achieve clinically acceptable accuracy of the digital impression [19, 20, 21]. [PERSON] et al. evaluated linear discrepancies of intraoral scanners between cylinders screwed on implant analogs in a stone model [22]. The authors demonstrated significant differences about the accuracy of the finish lines comparing the IOS [13]. However, it has been amply described the phenomenon of distortion in vivo full-arch impression. The accuracy of intraoral scanners has been previously examined by [PERSON] et al. [20] who measured the marginal fit of partial ceramic crowns, reporting significant