## 4 Discussion
Moreover, the selection of the digital scanner is highly relevant to provide a specific number of equilateral triangles of the tesella network, which can influence the accuracy of the measurement procedure. The accuracy of the STL digital files through intraoral and extraoral scan devices depends on multiple factors related to the scanning process, such as the presence of saliva, adjacent structures, teeth, light reflection, presence of blood, type of material used during scanning, and the time of the scanning process [22; 34], even though intraoral scan devices have reported smaller deviation values compared to extraoral scan devices [35]. [PERSON] et al. reported the influence of angle and distance of intraoral scan devices on the accuracy of the obtained STL digital files [36]; however, the accuracy of the obtained STL digital files has not been related to the distance of the extraoral scan device to the scanned object. [PERSON] et al. reported that intraoral scan devices provide more accuracy compared to extraoral scanners [34]. Moreover, [PERSON] and [PERSON] analyzed the accuracy of full-arch digital impressions using different intraoral scan devices and reported that the CEREC Bluecam scan showed a mean deviation of 80 \(\upmu\)m in the posterior areas of the dental arch, whereas iTero showed a mean deviation of 120 \(\upmu\)m and CEREC Omnicam showed a mean deviation of 130\(\upmu\)m. Nevertheless, no statistically significant differences were observed between the intraoral scan devices (\(p>0.05\)) [37]. In addition, [PERSON] et al. reported no statistically significant differences (\(p>0.05\)) between the accuracy of CEREC Bluecam, CEREC Omnicam, iTero, Lava COS, Lava True Definition, TRIOS, and TRIOS color digital for full-arch digital impressions [38]. However, [PERSON] et al. analyzed the trueness of full-arch digital impressions between three digital scanners and reported statistically significant differences (\(p<0.05\)) between the trueness values of the Lava True Definition and CEREC Omnicam; however, no statistically significant differences (\(p>0.05\)) were shown between the Lava True Definition and TRIOS. The standard deviation about the distance measurement was 23 \(\upmu\)m for 3M True Definition, 37 \(\upmu\)m for Heraeus Cara TRIOS, and 214 \(\upmu\)m for CEREC Omnicam. In addition, the angle measurement was for 0.06\({}^{\circ}\), 0.13\({}^{\circ}\), and 0.28\({}^{\circ}\) for True Definition, Heraeus Cara TRIOS, and CEREC Omnicam, respectively [39]. Moreover, [PERSON] et al. reported higher mean trueness of True Definition (21.8 \(\upmu\)m) than CEREC Bluecam (34.2 \(\upmu\)m), CEREC Omnicam (43.4 \(\upmu\)m), iTero (49.0 \(\upmu\)m), Lava COS (47.7 \(\upmu\)m), TRIOS (25.7 \(\upmu\)m), and TRIOS color (26.1 \(\upmu\)m) for partial lower arch scanning [40]. Moreover, power-dependent digital impression systems provide more accurate STL digital files than no-powder dependent digital impression systems because light refraction and scattering is prevented by the use of powder, which also allows for an accurate determination of object depth [41; 42]. Currently, there is no acquisition data system through digital scan devices that can be considered more accurate than others due to the lack of standardized protocols and randomized clinical trials [22]; however, [PERSON] et al. demonstrated that 3D models derived from optical scanners are 10 times more detailed in the number of tessellas in the network describing the tooth surface and 4-5 times more accurate in terms of standard deviation compared with experimental models obtained with CBCT with a standard resolution [43].