## 4 Discussion  
The purpose of this study was to assess the amount of occlusal error in the occlusal surface that was adjusted with the PSM compared to other methods, namely, using the traditional mechanical semi-adjustable articulator or current CAD software. The traditional method decreased the occlusal error based on the occlusal knowledge of the clinician and the skill of the technician [25]. For more accurate fabrication, the patient's condylar and anterior guidance and cranio-maxima-mandibular relationships were adjusted using a semi-adjustable articulator or fully adjustable articulator [13; 15]. Although simulated mandibular movement could contribute to reduced occlusal errors in the oral cavity [13], it was difficult to establish a full functional occlusion. With the development of digital technology, digital workflows are being applied in many areas of dentistry [42; 43]. Recently, dynamic occlusion has been used in CAD software by tracking and reproducing mandibular movement [7; 19]. The PSM is one such method. Because this method uses only an IOS, it reproduces the mandibular movement simply and quickly. However, to the author's knowledge, there is no research on whether digital workflows using the digitally reproduced dynamic occlusion are clinically superior to conventional methods. In this study, the deviations out of the tolerance level between the reference data (POST) and the comparison data (NA, PSM, and SA) were defined as occlusal errors that require occlusal adjustment. In other words, the RMS value represents the amount of occlusal error in the experimental groups. The RMS values of the occlusal surface in the NA, PSM, and SA groups were 168.2 \(\pm\) 43.3 \(\upmu\)m, 152.1 \(\pm\) 54.2 \(\upmu\)m, and 160.6 \(\pm\) 84.6 \(\upmu\)m, respectively. In addition, the RMS values of out of the tolerance level were 257.0 \(\pm\) 73.9 \(\upmu\)m, 202.3 \(\pm\) 39.8 \(\upmu\)m, and 222.9 \(\pm\) 41.9 \(\upmu\)m, respectively. In the case of the latter, there were statistically significant differences between the three groups. As a result, our null hypothesis was partially rejected. The result of the quantitative analysis signified that the overall occlusal surface did not differ between the three groups in single restorations in posterior teeth. It also suggested that all groups had occlusal errors in the oral cavity to some extent and required clinical intraoral adjustment. However, when limited to areas out of the tolerance level denoting occlusal errors, the extent of the errors was decreased in the adjusted PSM group. The RMS value did not measure the clinical quality but only the difference between the experimental data and the reference data. In further research, measures of clinical quality, such as the adjustment time, should be evaluated for dynamic occlusion, as recorded using PSM [44]. In a qualitative analysis by [PERSON] et al. [45], an occlusal morphology of a single crown using the FGP technique with the CAD/CAM (Computer-aided manufacturing) system was compared to a crown with static occlusion. The difference was mainly on the distobuccal portion of the occlusal surface. However, no statistical analysis was performed in this study. [PERSON] et al. [46] reported that a single crown designed by the FGP technique showed more significant changes in the occlusion and disocclusion times than those from conventional single crowns. The occlusion and disocclusion times were measured using a computerized occlusal analysis system (T-scan). The result indicated an easier occlusal adjustment in the FGP single crown, although the clinically relevant differences were small. In another study, [PERSON] et al. [47] studied an occlusal surface that was designed using a virtual mastication simulator. Comparing the obtained results with an actual tooth, these subject-specific functional occlusal surfaces displayed errors in functional and static occlusion, which ranged between 90 and 200 \(\upmu\)m. The result of that study is in agreement with our study.