## 4 Discussion  
In recent years, several case reports [12; 32; 33; 34; 14] and case series [14; 31] have dealt with TEMS as an emerging method of endodontic microsurgery, performed with either a pilot drill or a trephine. In the investigation conducted by [PERSON] et al., a digitally designed directional template proved to be a comprehensive facilitator for periapical surgery, surpassing initial expectations. The precision of root-end localization and resection was consistently achieved, simplifying the surgical procedure and elevating treatment efficiency. Notably, this technique demonstrated significant reductions in both damage and atrogenic injury [22]. [PERSON] et al. identified the guided microsurgical endodontic approach as a practicable method enabling predefined osteotomies and root resections [32]. [PERSON] et al. likewise established the utility of a CAD/CAM-guided surgical template in addressing intricate endodontic surgery scenarios [34]. Demonstrating the efficacy of a trephine-bur-assisted approach, [PERSON] et al. highlighted the superior speed and precision achieved compared with nonguided endodontic microsurgery [33]. [PERSON] et al. 's investigation endorsed TEMS-guided trephine bur root-end resection as comparably successful to conventional freehand bur resection [14]. Conclusively, [PERSON] et al. 's case series' findings endorsed the viability of guided trephination for root-end resection [31]. While the pilot drill approach  
Figure 7: A comparison of distal global deviation (DGD) between the drill and the trephine procedures (mean \(\pm\) SD). necessitates the subsequent extension of the osteotomy and the resection of the root end as a separate step, TEMS performed with a trephine is usually reported to make additional steps unnecessary. However, very few data are available about the accuracy of these techniques. The first preclinical study of this kind was published in 2007. In this 2007 study, [PERSON] and colleagues compared the use of a guided pilot drill with freehand osteotomy [11]. In their research, the DGD was found to be 0.79 \(\pm\) 0.33 mm for the procedures performed with guided pilot drills and 2.27 \(\pm\) 1.46 mm for the freehand procedures. It appears that the authors found a higher accuracy for the pilot drill procedure than we have in the present study (1.531 \(\pm\) 0.510 mm). The results are hard to compare; however, the pilot drill deviations in both studies are significantly smaller than those of the freehand results. On the one hand, the comparison is difficult because the [PERSON] group superimposed the pre- and postoperative models manually. Today, this is performed automatically based on grayscale values [30; 35], which makes the analysis more objective and reliable. In this study, we used grayscale-based digital superimposition too. On the other hand, [PERSON] et al. did not give an in-depth description of their study sample. It was mentioned that five operators performed osteectomies in all teeth in a duplicated mandible model, but exact numbers (e.g., about the number of the performed procedures) are not given at all: it only provides the 'operator factor', as aforementioned, to rule out this important feature during EMS procedures. Nevertheless, the study of the [PERSON] group can still be regarded as pioneering, with an essentially sound methodology. It was for this reason that we decided to take the same approach enhanced with up-to-date digital methods. Comparing the accuracy of the procedures performed with a pilot drill and a trephine, we found that the trephine procedure was characterized by a significantly smaller DGD (higher accuracy). However, it must be noted that the difference was quite small (0.22 mm between the means and 0.12 mm between the medians). From a clinical point of view, such a small difference is probably negligible.