## 1 Introduction  
Stabilized occlusion is important for maintaining functional equilibrium in the oral cavity [1]. Inappropriate dental occlusion causes clinical complications such as uncomfortable or painful bite, abnormal tooth mobility, restoration fractures, and occlusion-related temporomandibular joint dysfunction [2, 3]. It also lowers the long-term success of prosthodonic treatments [2]. Oclusal adjustment is a clinical procedure that removes the substrate of the occlusal surface of teeth or prostheses to fix deflective occlusion [4]. Oclusal treatment is essential and is performed in daily-routine practices. However, it is irreversible and requires an understanding of the coordinated interaction between dentition and neuro-muscular systems [5]. Owing to the clinical importance of occlusion, related knowledge on oral anatomy, jaw movement, and occlusal adjustment has been fundamental subjects in dental education [6].  
Learning effects are mainly influenced by the association of teaching modality and education topic [7]. Conventional pedagogics for occlusion education are based on traditional lectures, two-dimensional (2D) anatomical illustrations, and tangible anatomical models [8]. However, because of the dynamic nature of the occlusion and neuromuscular system in the oral cavity, conventional teaching methods have limitations in providing learners with adequate understanding of spatial dentition relations and practical procedures for occlusal adjustment [9]. Concepts of functional occlusion and subsequent occlusal adjustments are difficult to impart using such static methods [10].  
With advances in image processing, three-dimensional (3D) visualization technologies using computer modeling and design have improved medical education by making complex knowledge easier to present and teach [10; 11]. In dental education, 3D visualization techniques have been applied to multiple training courses such as caries removal, tooth preparation, third molar extraction, gingival pocket probing, and dental calculus removal. [12; 13; 14; 15; 16]. Compared with 2D illustrations, 3D visualization allows for the complicated spatial relationships of the dentition to be presented in a 3D polygonal mesh format. Moreover, as the 3D dentition and jaw models can be managed using computer software, learners can perform virtual analysis, planning, and treatment practices on the 3D models [17]. The virtual simulation enhances the spatial memory storage, attention, and perception of learners [18]. This is because the cognitive processes of the human brain can be facilitated during the navigation and exploration of a virtual environment [19].  
Education methods assisted by computer software have been reported to be equal or superior to traditional teaching systems for knowledge acquisition in medical fields [10]. Three-dimensional visualization and simulation could improve learning effects in occlusion education by providing students with 3D perception of occlusion and the virtual space for practice. However, the effects of such digital methods have not been thoroughly investigated. The purpose of this study is to evaluate the effects of a computer-based 3D simulation method on learner response and learning effects for the principles of occlusal adjustment in undergraduate dental students. It is then compared with a traditional approach that uses paper-based 2D illustrations. The first null hypothesis was that there is no difference in learning effects between the paper-based 2D presentation and computer-based 3D simulation methods. The second null hypothesis was that learner response on the education method and the actual examination results would not be correlated.