## 4 Discussion
Some studies have evaluated the precision of different orthodontic measurements obtained from dental casts and 3D-printed casts [29]. However, a limitation of these studies is the use of a tabletop scanner to obtain 3D images of scanned dental casts because this method introduces the risk of replicating errors that may be present in the original casts; therefore, it is necessary to consider alternative methods for obtaining these records. The intraoral scanner is akey piece of equipment in the transition toward the digital development of diagnoses and treatment plans. The precision and reliability of intraoral scanners have been evaluated in several studies by comparing their results with those obtained using conventional dental casts. The results obtained from intraoral scans appear to be reliable and accurate compared to those obtained from conventional impressions, with the additional advantage of eliminating the need for impression materials and increasing the personalization of treatment [30, 31, 32]. [PERSON] et al. 2019 evaluated the accuracy of measurements obtained with the TRIOS intraoral scanner and the 3 Shape OrthoAnalyzer software, compared with measurements obtained on conventional plaster models. No statistically significant difference between groups was observed. Although statistically significant differences were observed for the time needed to perform the analysis, being shorter with digital models [33]. Nevertheless, previous studies reported errors in measurements for occlusoervical mesiodistal and intercanine and intermalor widths with intraoral scanners when compared with their 3D printed counterparts and the conventional casts [34]. However, these errors are considered within the clinically acceptable level, and in this study, the agreement between intraoral scanners and conventional casts was considered a good agreement. Studies have reported on the accuracy and efficacy of intraoral scanners for the orthodontic purpose to provide clinically useful information [35]. The TRIOS intraoral scanner has demonstrated better precision when compared with other intraoral scanners such as Carestream CS3600 and Sirona Omnicam [36, 37]. On the other hand, iTero showed better results than the extraoral scanner, Ortho Insight 3D, and similar reliability to the intraoral scanner, Lythos [38]. Regarding different scanning systems, studies have noted that there are no significant differences between digital models obtained through intraoral scanning and those obtained by scanning conventional dental casts based on impressions [39, 40, 41]. Other authors claim that when few measurements are obtained, intraoral scanning can be more accurate than scans of dental casts [42]. In the development of this study, two intraoral scanners were used to obtain the digital models to control possible bias and directly obtain oral anatomy records for each patient. These devices proved to be a reliable alternative for diagnosing and planning orthodontic treatment as no statistically significant differences were observed between the ABO discrepancy index scores that were obtained digitally and those obtained using conventional plaster models. With respect to the different indices or analyses that provide a final score based on more than one type of diagnostic record, some studies have compared the analysis of digital models with the manual analysis of 3D printed models using ABO's objective classification system for dental models and panoramic radiographs. These studies reported that the scores obtained using digital analysis were significantly higher than those obtained using manual analysis, especially for the alignment and rotation sections [43]. Such findings are inconsistent with those of our study, which found no difference between the scores based on manual measurements of plaster models and those obtained using the digital technique. This difference may be explained by the use of 3D printed models, which can differ from the original dimensions in a patient's dental records [29]. A study developed in 2015 by [PERSON] et al.