## 5 Discussion  
The advancement in augmented reality headsets has the potential to improve or even replace computer-aided dynamic navigational systems in implantology, making them more approachable for practitioners. This statement can be backed by the recent study by [PERSON] et al., suggesting that the accuracy of dental implant navigation with the use of AR is comparable to conventional implant-guided techniques [26]. This study evaluated the capabilities of the commercially available AR headset HoloLens 2 in the application of dentistry practice, specifically in implantology, using a custom-designed marker. Marker accuracy analysis was separated into two experimental setups: calibration and virtual model perception analysis. In calibration experiments, the majority of trueness and precision results surpass the 1 mm threshold in distance-related measurements (\(\Delta_{\text{D}}\) and \(\Delta_{\text{K}}\), respectively). Angle results disperse in a wide range, implying that the calibration results could contrast significantly after each calibration. In terms of dynamic navigation system accuracy, these calibration results could double the error in the commonly presented distance between the implant top (1.02 mm) and bottom bases (1.33 mm) or angle (3.59\({}^{\circ}\))-related measures [27]. Therefore, the use of additive error mitigation techniques should be applied for further use. The results of the perception accuracy of the virtual model showed a significant dependence on the settings. However, it is more prominent in trueness data than in precision data sets. This can be explained by complexity and made assumptions about the trueness data measurement scheme where video recordings were chosen instead of raw three-dimensional data. Furthermore, differences in positional data in both calibration and virtual model perspectives are noticeable. The result of the statistical analysis confirms it, which subsequently led to the rejection (\(p<0.001\)) of both null hypotheses. It could be explained in two possible ways: changes in marker distance from the headset or changes in marker tracing reliability with changing angles. One of the limitations of this study is the chosen marker and probe development procedure, which involves the overreliance on the existing Vuforia library for the creation of trackers. The choice of marker texture and dimensions was in accordance with the presented library guidelines, which limit the usage in the context of accuracy research. Although planar fiducial marker-based tracking is the most widely used method with HoloLens among researchers [12], it is arguably not the only way for an AR headset to interact with the real world, as mentioned in the Introduction section (Section 1). One proposal was made by [PERSON] et al. [28], which involves retro-reflective spheres with a measured root mean square error of 1.7 mm and 1.11\({}^{\circ}\) compared to fiducial ArUco markers with 6.09 mm and 6.73\({}^{\circ}\) in distance- and angle-related measures. Another step further for registration and tracking is to detect and track the objects without relying on prior knowledge or the presence of predefined markers [29]. This marker-less approach is still in the infant stage due to the current limited headset computational capabilities. However, the possibility to track the object without the use of any other secondary objects is promising since, in addition to the aforementioned sterility, it would free up the already confined surgery space. Furthermore, the mentioned trueness measurements from video data may be more conclusive if a reference measurement system was included. Lastly, the experiments were carried out by only one person, which arguably shows bias in the presented results. Nevertheless, the second iteration of HoloLens is observed to have restricted use in applications that require high accuracy, as it barely reaches the millimeter range [12; 30]; however, some promising results have begun to emerge [25].