Augmented reality (AR) technology has proven effective in displaying information and rendering 3D objects. Although students commonly use AR applications through mobile devices, plastic models or 2D images are still widely used in teeth cutting exercises. Due to the three-dimensional nature of teeth, dental carving students face challenges due to the lack of available tools that provide consistent guidance. In this study, we developed an AR-based dental carving training tool (AR-TCPT) and compared it with a plastic model to evaluate its potential as a practice tool and the experience with its use.
To simulate cutting teeth, we sequentially created a 3D object that included a maxillary canine and maxillary first premolar (step 16), a mandibular first premolar (step 13), and a mandibular first molar (step 14). Image markers created using Photoshop software were assigned to each tooth. Developed an AR-based mobile application using the Unity engine. For dental carving, 52 participants were randomly assigned to a control group (n = 26; using plastic dental models) or an experimental group (n = 26; using AR-TCPT). A 22-item questionnaire was used to evaluate user experience. Comparative data analysis was carried out using the nonparametric Mann-Whitney U test through the SPSS program.
AR-TCPT uses a mobile device’s camera to detect image markers and display 3D objects of tooth fragments. Users can manipulate the device to review each step or study the shape of a tooth. The results of the user experience survey showed that compared to the control group using plastic models, the AR-TCPT experimental group scored significantly higher on teeth carving experience.
Compared with traditional plastic models, AR-TCPT provides better user experience when carving teeth. The tool is easy to access as it is designed to be used by users on mobile devices. Further research is needed to determine the educational impact of AR-TCTP on the quantification of engraved teeth as well as the user’s individual sculpting abilities.
Dental morphology and practical exercises are an important part of the dental curriculum. This course provides theoretical and practical guidance on the morphology, function and direct sculpting of tooth structures [1, 2]. The traditional method of teaching is to study theoretically and then perform tooth carving based on the principles learned. Students use two-dimensional (2D) images of teeth and plastic models to sculpt teeth on wax or plaster blocks [3,4,5]. Understanding dental morphology is critical for restorative treatment and fabrication of dental restorations in clinical practice. The correct relationship between antagonist and proximal teeth, as indicated by their shape, is essential to maintain occlusal and positional stability [6, 7]. Although dental courses can help students gain a thorough understanding of dental morphology, they still face challenges in the cutting process associated with traditional practices.
Newcomers to the practice of dental morphology are faced with the challenge of interpreting and reproducing 2D images in three dimensions (3D) [8,9,10]. Tooth shapes are usually represented by two-dimensional drawings or photographs, leading to difficulties in visualizing dental morphology. Additionally, the need to quickly perform dental carving in limited space and time, coupled with the use of 2D images, makes it difficult for students to conceptualize and visualize 3D shapes [11]. Although plastic dental models (which can be presented as partially completed or in final form) assist in teaching, their use is limited because commercial plastic models are often predefined and limit practice opportunities for teachers and students[4]. Additionally, these exercise models are owned by the educational institution and cannot be owned by individual students, resulting in increased exercise burden during the allotted class time. Trainers often instruct large numbers of students during practice and often rely on traditional practice methods, which can result in long waits for trainer feedback on intermediate stages of carving [12]. Therefore, there is a need for a carving guide to facilitate the practice of tooth carving and to alleviate the limitations imposed by plastic models.
Augmented reality (AR) technology has emerged as a promising tool for improving the learning experience. By overlaying digital information onto a real-life environment, AR technology can provide students with a more interactive and immersive experience [13]. Garzón [14] drew on 25 years of experience with the first three generations of AR education classification and argued that the use of cost-effective mobile devices and applications (via mobile devices and applications) in the second generation of AR has significantly improved educational attainment characteristics. . Once created and installed, mobile applications allow the camera to recognize and display additional information about recognized objects, thereby improving the user experience [15, 16]. AR technology works by quickly recognizing a code or image tag from a mobile device’s camera, displaying overlaid 3D information when detected [17]. By manipulating mobile devices or image markers, users can easily and intuitively observe and understand 3D structures [18]. In a review by Akçayır and Akçayır [19], AR was found to increase “fun” and successfully “increase levels of learning participation.” However, due to the complexity of the data, the technology can be “difficult for students to use” and cause “cognitive overload,” requiring additional instructional recommendations [19, 20, 21]. Therefore, efforts should be made to enhance the educational value of AR by increasing usability and reducing task complexity overload. These factors need to be considered when using AR technology to create educational tools for the practice of tooth carving.
To effectively guide students in dental carving using AR environments, a continuous process must be followed. This approach can help reduce variability and promote skill acquisition [22]. Beginning carvers can improve the quality of their work by following a digital step-by-step tooth carving process [23]. In fact, a step-by-step training approach has been shown to be effective in mastering sculpting skills in a short time and minimizing errors in the final design of the restoration [24]. In the field of dental restoration, the use of engraving processes on the surface of teeth is an effective way to help students improve their skills [25]. This study aimed to develop an AR-based dental carving practice tool (AR-TCPT) suitable for mobile devices and evaluate its user experience. In addition, the study compared the user experience of AR-TCPT with traditional dental resin models to evaluate the potential of AR-TCPT as a practical tool.
AR-TCPT is designed for mobile devices using AR technology. This tool is designed to create step-by-step 3D models of maxillary canines, maxillary first premolars, mandibular first premolars, and mandibular first molars. Initial 3D modeling was carried out using 3D Studio Max (2019, Autodesk Inc., USA), and final modeling was carried out using Zbrush 3D software package (2019, Pixologic Inc., USA). Image marking was carried out using Photoshop software (Adobe Master Collection CC 2019, Adobe Inc., USA), designed for stable recognition by mobile cameras, in the Vuforia engine (PTC Inc., USA; http:///developer.vuforia.com) ) . The AR application is implemented using the Unity engine (March 12, 2019, Unity Technologies, USA) and subsequently installed and launched on a mobile device. To evaluate the effectiveness of AR-TCPT as a tool for dental carving practice, participants were randomly selected from the dental morphology practice class of 2023 to form a control group and an experimental group. Participants in the experimental group used AR-TCPT, and the control group used plastic models from the Tooth Carving Step Model Kit (Nissin Dental Co., Japan). After completing the teeth cutting task, the user experience of each hands-on tool was investigated and compared. The flow of the study design is shown in Figure 1. This study was conducted with the approval of the Institutional Review Board of South Seoul National University (IRB number: NSU-202210-003).
3D modeling is used to consistently depict the morphological characteristics of the protruding and concave structures of the mesial, distal, buccal, lingual and occlusal surfaces of teeth during the carving process. The maxillary canine and maxillary first premolar teeth were modeled as level 16, the mandibular first premolar as level 13, and the mandibular first molar as level 14. The preliminary modeling depicts the parts that need to be removed and retained in the order of dental films, as shown in the figure. 2. The final tooth modeling sequence is shown in Figure 3. In the final model, textures, ridges and grooves describe the depressed structure of the tooth, and image information is included to guide the sculpting process and highlight structures that require close attention. At the beginning of the carving stage, each surface is color coded to indicate its orientation, and the wax block is marked with solid lines indicating the parts that need to be removed. The mesial and distal surfaces of the tooth are marked with red dots to indicate tooth contact points that will remain as projections and will not be removed during the cutting process. On the occlusal surface, red dots mark each cusp as preserved, and red arrows indicate the direction of engraving when cutting the wax block. 3D modeling of retained and removed parts allows confirmation of the morphology of the removed parts during subsequent wax block sculpting steps.
Create preliminary simulations of 3D objects in a step-by-step tooth carving process. a: Mesial surface of the maxillary first premolar; b: Slightly superior and mesial labial surfaces of the maxillary first premolar; c: Mesial surface of the maxillary first molar; d: Slightly maxillary surface of the maxillary first molar and mesiobuccal surface. surface. B – cheek; La – labial sound; M – medial sound.
Three-dimensional (3D) objects represent the step-by-step process of cutting teeth. This photo shows the finished 3D object after the maxillary first molar modeling process, showing details and textures for each subsequent step. The second 3D modeling data includes the final 3D object enhanced in the mobile device. The dotted lines represent equally divided sections of the tooth, and the separated sections represent those that must be removed before the section containing the solid line can be included. The red 3D arrow indicates the cutting direction of the tooth, the red circle on the distal surface indicates the tooth contact area, and the red cylinder on the occlusal surface indicates the cusp of the tooth. a: dotted lines, solid lines, red circles on the distal surface and steps indicating the detachable wax block. b: Approximate completion of the formation of the first molar of the upper jaw. c: Detail view of maxillary first molar, red arrow indicates direction of tooth and spacer thread, red cylindrical cusp, solid line indicates part to be cut on occlusal surface. d: Complete maxillary first molar.
To facilitate the identification of successive carving steps using the mobile device, four image markers were prepared for the mandibular first molar, mandibular first premolar, maxillary first molar, and maxillary canine. Image markers were designed using Photoshop software (2020, Adobe Co., Ltd., San Jose, CA) and used circular number symbols and a repeating background pattern to distinguish each tooth, as shown in Figure 4. Create high-quality image markers using the Vuforia engine (AR marker creation software), and create and save image markers using the Unity engine after receiving a five-star recognition rate for one type of image. The 3D tooth model is gradually linked to image markers, and its position and size are determined based on the markers. Uses the Unity engine and Android applications that can be installed on mobile devices.
Image tag. These photographs show the image markers used in this study, which the mobile device camera recognized by tooth type (number in each circle). a: first molar of the mandible; b: first premolar of the mandible; c: maxillary first molar; d: maxillary canine.
Participants were recruited from the first year practical class on dental morphology of the Department of Dental Hygiene, Seong University, Gyeonggi-do. Potential participants were informed of the following: (1) Participation is voluntary and does not include any financial or academic remuneration; (2) The control group will use plastic models, and the experimental group will use AR mobile application; (3) the experiment will last three weeks and involve three teeth; (4) Android users will receive a link to install the application, and iOS users will receive an Android device with AR-TCPT installed; (5) AR-TCTP will work in the same way on both systems; (6) Randomly assign the control group and the experimental group; (7) Teeth carving will be performed in different laboratories; (8) After the experiment, 22 studies will be conducted; (9) The control group can use AR-TCPT after the experiment. A total of 52 participants volunteered, and an online consent form was obtained from each participant. The control (n = 26) and experimental groups (n = 26) were randomly assigned using the random function in Microsoft Excel (2016, Redmond, USA). Figure 5 shows the recruitment of participants and the experimental design in a flow chart.
A study design to explore participants’ experiences with plastic models and augmented reality applications.
Starting March 27, 2023, the experimental group and control group used AR-TCPT and plastic models to sculpt three teeth, respectively, for three weeks. Participants sculpted premolars and molars, including a mandibular first molar, a mandibular first premolar, and a maxillary first premolar, all with complex morphological features. The maxillary canines are not included in the sculpture. Participants have three hours a week to cut a tooth. After fabrication of the tooth, the plastic models and image markers of the control and experimental groups, respectively, were extracted. Without image label recognition, 3D dental objects are not enhanced by AR-TCTP. To prevent the use of other practice tools, the experimental and control groups practiced teeth carving in separate rooms. Feedback on tooth shape was provided three weeks after the end of the experiment to limit the influence of teacher instructions. The questionnaire was administered after the cutting of the mandibular first molars was completed in the third week of April. A modified questionnaire from Sanders et al. Alfala et al. used 23 questions from [26]. [27] assessed differences in heart shape between practice instruments. However, in this study, one item for direct manipulation at each level was excluded from the Alfalah et al. [27]. The 22 items used in this study are shown in Table 1. The control and experimental groups had Cronbach’s α values of 0.587 and 0.912, respectively.
Data analysis was performed using SPSS statistical software (v25.0, IBM Co., Armonk, NY, USA). A two-sided significance test was performed at a significance level of 0.05. Fisher’s exact test was used to analyze general characteristics such as gender, age, place of residence, and dental carving experience to confirm the distribution of these characteristics between the control and experimental groups. The results of the Shapiro-Wilk test showed that the survey data were not normally distributed (p < 0.05). Therefore, the nonparametric Mann-Whitney U test was used to compare the control and experimental groups.
The tools used by the participants during the teeth carving exercise are shown in Figure 6. Figure 6a shows the plastic model, and Figures 6b-d show the AR-TCPT used on a mobile device. AR-TCPT uses the device’s camera to identify image markers and displays an enhanced 3D dental object on the screen that participants can manipulate and observe in real time. The “Next” and “Previous” buttons of the mobile device allow you to observe in detail the stages of carving and the morphological characteristics of the teeth. To create a tooth, AR-TCPT users sequentially compare an enhanced 3D on-screen model of the tooth with a wax block.
Practice teeth carving. This photograph shows a comparison between traditional tooth carving practice (TCP) using plastic models and step-by-step TCP using augmented reality tools. Students can watch the 3D carving steps by clicking the Next and Previous buttons. a: Plastic model in a set of step-by-step models for carving teeth. b: TCP using an augmented reality tool on the first stage of the mandibular first premolar. c: TCP using an augmented reality tool during the final stage of mandibular first premolar formation. d: Process of identifying ridges and grooves. IM, image label; MD, mobile device; NSB, “Next” button; PSB, “Previous” button; SMD, mobile device holder; TC, dental engraving machine; W, wax block
There were no significant differences between the two groups of randomly selected participants in terms of gender, age, place of residence, and dental carving experience (p > 0.05). The control group consisted of 96.2% women (n = 25) and 3.8% men (n = 1), whereas the experimental group consisted of only women (n = 26). The control group consisted of 61.5% (n = 16) of participants aged 20 years, 26.9% (n = 7) of participants aged 21 years, and 11.5% (n = 3) of participants aged ≥ 22 years, then the experimental control group consisted of 73.1% (n = 19) of participants aged 20 years, 19.2% (n = 5) of participants aged 21 years, and 7.7% (n = 2) of participants aged ≥ 22 years . In terms of residence, 69.2% (n=18) of the control group lived in Gyeonggi-do, and 23.1% (n=6) lived in Seoul. In comparison, 50.0% (n = 13) of the experimental group lived in Gyeonggi-do, and 46.2% (n = 12) lived in Seoul. The proportion of control and experimental groups living in Incheon was 7.7% (n = 2) and 3.8% (n = 1), respectively. In the control group, 25 participants (96.2%) had no previous experience with teeth carving. Similarly, 26 participants (100%) in the experimental group had no previous experience with teeth carving.
Table 2 presents descriptive statistics and statistical comparisons of each group’s responses to the 22 survey items. There were significant differences between the groups in responses to each of the 22 questionnaire items (p < 0.01). Compared to the control group, the experimental group had higher mean scores on the 21 questionnaire items. Only on question 20 (Q20) of the questionnaire did the control group score higher than the experimental group. The histogram in Figure 7 visually displays the difference in mean scores between groups. Table 2; Figure 7 also shows the user experience results for each project. In the control group, the highest-scoring item had question Q21, and the lowest-scoring item had question Q6. In the experimental group, the highest-scoring item had question Q13, and the lowest-scoring item had question Q20. As shown in Figure 7, the largest difference in mean between the control group and the experimental group is observed in Q6, and the smallest difference is observed in Q22.
Comparison of questionnaire scores. Bar graph comparing the average scores of the control group using the plastic model and the experimental group using the augmented reality application. AR-TCPT, an augmented reality based dental carving practice tool.
AR technology is becoming increasingly popular in various fields of dentistry, including clinical aesthetics, oral surgery, restorative technology, dental morphology and implantology, and simulation [28, 29, 30, 31]. For example, Microsoft HoloLens provides advanced augmented reality tools to improve dental education and surgical planning [32]. Virtual reality technology also provides a simulation environment for teaching dental morphology [33]. Although these technologically advanced hardware-dependent head-mounted displays have not yet become widely available in dental education, mobile AR applications can improve clinical application skills and help users quickly understand anatomy [34, 35]. AR technology can also increase students’ motivation and interest in learning dental morphology and provide a more interactive and engaging learning experience [36]. AR learning tools help students visualize complex dental procedures and anatomy in 3D [37], which is critical to understanding dental morphology.
The impact of 3D printed plastic dental models on teaching dental morphology is already better than textbooks with 2D images and explanations [38]. However, digitalization of education and technological progress have made it necessary to introduce various devices and technologies in healthcare and medical education, including dental education [35]. Teachers are faced with the challenge of teaching complex concepts in a rapidly evolving and dynamic field [39], which requires the use of various hands-on tools in addition to traditional dental resin models to assist students in the practice of dental carving. Therefore, this study presents a practical AR-TCPT tool that uses AR technology to assist in the practice of dental morphology.
Research on the user experience of AR applications is critical to understanding the factors influencing multimedia use [40]. A positive AR user experience can determine the direction of its development and improvement, including its purpose, ease of use, smooth operation, information display, and interaction [41]. As shown in Table 2, with the exception of Q20, the experimental group using AR-TCPT received higher user experience ratings compared to the control group using plastic models. Compared with plastic models, the experience of using AR-TCPT in dental carving practice was highly rated. Assessments include comprehension, visualization, observation, repetition, usefulness of tools, and diversity of perspectives. Benefits of using AR-TCPT include rapid comprehension, efficient navigation, time savings, development of preclinical engraving skills, comprehensive coverage, improved learning, reduced textbook dependence, and the interactive, enjoyable, and informative nature of the experience. AR-TCPT also facilitates interaction with other practice tools and provides clear views from multiple perspectives.
As shown in Figure 7, AR-TCPT proposed an additional point in question 20: a comprehensive graphical user interface showing all steps of tooth carving is needed to help students perform tooth carving. Demonstration of the entire dental carving process is critical to developing dental carving skills before treating patients. The experimental group received the highest score in Q13, a fundamental question related to helping develop dental carving skills and improve user skills before treating patients, highlighting the potential of this tool in dental carving practice. Users want to apply the skills they learn in a clinical setting. However, follow-up studies are needed to evaluate the development and effectiveness of actual tooth carving skills. Question 6 asked whether plastic models and AR-TCTP could be used if necessary, and responses to this question showed the largest difference between the two groups. As a mobile app, AR-TCPT proved to be more convenient to use compared to plastic models. However, it remains difficult to prove the educational effectiveness of AR apps based on user experience alone. Further studies are needed to evaluate the effect of AR-TCTP on finished dental tablets. However, in this study, the high user experience ratings of AR-TCPT indicate its potential as a practical tool.
This comparative study shows that AR-TCPT can be a valuable alternative or complement to traditional plastic models in dental offices, as it received excellent ratings in terms of user experience. However, determining its superiority will require further quantification by instructors of intermediate and final carved bone. In addition, the influence of individual differences in spatial perception abilities on the carving process and the final tooth also needs to be analyzed. Dental capabilities vary from person to person, which can affect the carving process and the final tooth. Therefore, more research is needed to prove the effectiveness of AR-TCPT as a tool for dental carving practice and to understand the modulating and mediating role of AR application in the carving process. Future research should focus on evaluating the development and evaluation of dental morphology tools using advanced HoloLens AR technology.
In summary, this study demonstrates the potential of AR-TCPT as a tool for dental carving practice as it provides students with an innovative and interactive learning experience. Compared to the traditional plastic model group, the AR-TCPT group showed significantly higher user experience scores, including benefits such as faster comprehension, improved learning, and reduced textbook dependency. With its familiar technology and ease of use, AR-TCPT offers a promising alternative to traditional plastic tools and can help newbies to 3D sculpting. However, further research is needed to evaluate its educational effectiveness, including its impact on people’s sculpting abilities and the quantification of sculpted teeth.
The datasets used in this study are available by contacting the corresponding author on reasonable request.
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Post time: Dec-25-2023