## 2 Materials and Methods  
Figure 1 provides a summary of the workflow of the study, which was approved by the ethics research board of Kyungpook National University (KNUDH-2020-03-06). The study was conducted on 60 dental students, wherein recruitment was limited to second-year dental undergraduate students from the school of dentistry of one university. All the students followed the same curriculum. This inclusion criterion was applied to control for confounding factors that may influence the results, such as background of dental knowledge and practice experiences. The power analysis method was used to determine the number of participants per group (effect size \(f\) = 0.597, \(\alpha\) = 0.05, power = 0.8, standard deviation = 10.3, number of groups = 3) [10]. All participants were blinded to the objective of the study and randomly assigned into three groups (\(n\) = 20) using the adaptive pair-matching method based on grade point average [11].  
The three abovementioned protocols were individually used to teach the students, under the L, Lts, and LwS groups, respectively, the guidance of the mandibular movement. Conventional lecture methods using a textbook and 2D illustrations were employed to teach the L group (Figure 2) [12]. Students in the Lts group were taught with the conventional lecture method followed by computer-aided 3D simulation using a computer design software program (R2 CAD; MegaGen, Daegu, Korea) to simulate the movements of the mandible (Figure 3). Meanwhile, students in the LwS group were simultaneously taught using the conventional lecture and computer-aided 3D simulation methods. An experienced instructor delivered the lesson content for all groups.  
To assess learning outcomes, a paper-based examination (Supplementary Materials S1) was conducted on the day of the lesson. The examination comprised nine closed-ended questions [13] that aimed to investigate the understanding of the students regarding the anterior and posterior determinants of occlusion and mandibular movement. Students were given scores on a scale of 0-100. The numerical scores were then converted to letter grades as follows: A = \(>\)90 to \(\leq\)100, B = \(>\)80 to \(\leq\)90, C = \(>\)70 to \(\leq\)80, D = \(>\)60 to \(\leq\)70, and F = \(\leq\)60, with A being the highest and F being the lowest grade [11]. Scoring was conducted twice; first, by the students to constitute expected grades and second by the course instructor as actual grades. Upon completion of data collection and to adhere to research ethics protocols, later in the semester, students in the lecture group were taught using the 3D simulation method, and students in the 3D simulation group were taught using the lecture method.  
Figure 1: Workflow for this study.  
Figure 3: Computer visualization and simulation method with three-dimensional models.  
Figure 2: Lecture-based teaching method with two-dimensional schematic illustrations.  
The means and standard deviations of the actual and expected scores were calculated. Analysis of variance with [PERSON]'s post-hoc analysis was used for comparing between teaching protocols, whereas the independent \(t\) test was used for the actual and expected scores. All statistical analyses were performed using a statistical software program (IBM SPSS Statistics, v25.0; IBM Corp, Armonk, NY, USA). A \(p\) value of 0.05 was considered significant.