Comparative study on the effectiveness of virtual simulation and jaw model for undergraduate periodontal teaching

To compare the effect of virtual simulation and jaw model on the development of pre-clinical periodontal skills in undergraduate students and to improve future pre-clinical training strategies. Sixty volunteer sophomores and juniors from the stomatology at Lanzhou University were enrolled in the current study and randomly divided into four groups: Jaw model (Group J, the control group), Virtual reality (Group V), Virtual-Jaw (Group V-J), and Jaw-Virtual (Group J-V). All of the participants received training on uniform basic periodontal knowledge before completing the rst theoretical assessment. Then, they obtained total 8 hours of operation training and completed a second theoretical assessment. Their performance was evaluated using the supragingival scaling processes, and clinical operation scores were graded by a blinded professional using an established standard scoring system.


Abstract Background
To compare the effect of virtual simulation and jaw model on the development of pre-clinical periodontal skills in undergraduate students and to improve future pre-clinical training strategies.

Methods
Sixty volunteer sophomores and juniors from the stomatology at Lanzhou University were enrolled in the current study and randomly divided into four groups: Jaw model (Group J, the control group), Virtual reality (Group V), Virtual-Jaw (Group V-J), and Jaw-Virtual (Group J-V). All of the participants received training on uniform basic periodontal knowledge before completing the rst theoretical assessment.
Then, they obtained total 8 hours of operation training and completed a second theoretical assessment.
Their performance was evaluated using the supragingival scaling processes, and clinical operation scores were graded by a blinded professional using an established standard scoring system.

Results
There was no signi cant difference in the rst theoretical outcomes between the four groups (P > 0.05).
The second theoretical scores of the V-J and J-V group (60.00 ± 4.47, 58. 33 ± 4.35) were signi cantly improved as compared with the rst theoretical scores (49.67 ± 4.81, 48.00 ± 4.93, P < 0.05). The operation process scores of students in Group V-J and J-V (72.00 ± 5.92; 70.00 ± 3.05) were higher than those in the other two groups (V: 61.67 ± 7.85; J: 60.67 ± 2.58). Additionally, the scaling process performance of students in Group V-J and J-V (53.00 ± 3.05; 63.40 ± 4.39) was improved as compared with that of students in the other two groups (V: 41.90 ± 5.23; J: 47.40 ± 4.31).

Conclusion
The combination of virtual reality and jaw model during periodontal pre-clinical training may improve students' grades and help them develop professional skill. More importantly, we suggest that the jaw model should be applied prior to virtual reality.

Background
Virtual reality (VR) provides the possibility to emulate the real world and was rst introduced by Ivan Sutherland in the mid-1960s [1]. Currently available immersive VR technologies have been used in different elds, such as gaming [2], transportation [3], military [4], architectural engineering [5], and education [6]. Among them, VR has been increasingly used in various areas of clinical medicine [7].
Findings from previous studies suggest that VR intervention can be used to effectively reduce acute pain [8] and provide a virtual environment with well-controlled sensory stimuli for the treatment of mental disorders, such as dementia, mild cognitive impairment (MCI), schizophrenia, and autism [9]. In addition, VR technology has also been applied in rehabilitation treatment to improve the posture and gait of individuals with nerve injury [10], and reduces psychological symptoms and helps support emotional health during cancer treatment [11]. Remarkably, the application of VR in the eld of stomatology has mainly focused on dental education, maxillofacial surgery, the treatment of oral diagnosis, and treatment of fear [12]. Adequate pre-clinical training is essential for the successful career development of dentists. Traditional pre-clinical training in stomatology is mainly conducted on the simulation model of the jaw, and the pattern is unitary, which makes the operation not t with the disease's complex clinical manifestations. And then, students in that training limited by get timely and unrealistic feedback, produces defects contain low e ciency, poor training effect.
Recently, with the growing accessibility of computer-assisted VR technology in dental research, various dental virtual simulation systems have emerged that are used for oral operation teaching and pre-clinical training in some colleges. There is increasing awareness of the importance of improved teaching skills during undergraduate education. Urbankova et al [13] tested manual agility using tactile VR technology in preclinical dental education and con rmed that the VR simulator played a signi cant role in identifying students who experience learning challenges in the preclinical phase of dental training. Another study evaluated the validation training simulator for inferior alveolar nerve block and concluded that it was suitable for needle appropriate positioning, insertion depth, and resistance sensitivity of virtual tissues [14]. Obviously, it is essential to establish a sound teaching model for undergraduate education.
Despite the rapid progress in virtual simulation within the eld of medical education, its universal access remains limited. Most studies have simulated maxillofacial surgical [15], Local anaesthesia [16], and dental pulp surgical trainings [17], however, few reports have focused on simulated periodontal teaching.
Periodontitis has high prevalence and affects 5.4 billion (90%) people worldwide [18]. The routine practice for a soft tissue examination and periodontal intervention treatment consists of periodontal probing, supragingival and subgingival scaling, and root planing, which are all essential manipulation skills for undergraduates. However, students require extensive training in order to acquire these skills.
Unfortunately, the traditional jaw training model often fails to achieve satisfactory results. Thus, in the present experiment, we explored the effectiveness of VR in periodontal pre-clinical training and provided adequate performance mode in basic periodontal education.

Methods
This study was approved by Ethics Committee of the School of Stomatology Lanzhou University (No. LZUKQ-2019- 25), and all students provided written informed consent to participate in this study. Besides, all the experiment protocol for involving humans was in accordance to Declaration of Helsinki.

Participants
We randomly selected 60 volunteer second-and third-year undergraduate students attending stomatology at Lanzhou University who were in good periodontal condition and did not have any other systemic diseases. The participants were divided into the following four groups (n = 15) at an equal gender ratio: (1) the Jaw model (Group J) was the control group, (2) the Virtual reality (Group V), (3) the Virtual-Jaw (Group V-J), (4) the Jaw-Virtual (Group J-V). The age of the participants ranged from 19-20 years did not differ signi cantly. Additionally, none of the students received any periodontology knowledge before the begging of our study, and they all shared the same starting point.

Theoretical knowledge teaching
A ow chart that illustrates the study design is shown in Fig. 1. Before Exam 1, the students attended 2 hours period of a theoretical knowledge classroom section taught by a periodontist who had more than 10 years of clinical experience. The lecture content comprised tissue anatomy, comprehensive periodontal examination (e.g., probing pocket depth [PPD], bleeding on probing [BOP], and clinical attachment level [CAL]), subgingival scaling, preoperative preparation, and instrument selection (Fig. 2), the lecture was based on the criteria outlined in the Periodontology textbook fourth edition [19]. Exam 1 scores assessed potential learning ability and consisted of multiple-choice questions.

Operation teaching
The students received hands-on operation teaching training that included the following techniques: plaque index record, medical history inquiry, aseptic concept, equipment preparation, chair position adjustment, comprehensive periodontal examination, supragingival scaling, postoperative examination, and oral health education ( Fig. 3A/B). The students received hands-on training that lasted approximately 8 hours of training total (2 h/day). Set up left maxillary central incisor (21) and right mandibular rst molar (46) as uniform sites. Additionally, the training order of groups V-J and J-V were reversed to eliminate the order factor. Further, the V-J and J-V groups of students were trained on the jaw model (NISSIN) (Fig. 3C) and the virtual reality system (UniDental) (Fig. 3D) for 4 hours respectively in order to explore whether the order of two methods in uenced the training outcomes.

Operation examination
The students completed the second theoretical knowledge exam (e.g., Exam 2) after the operation training and performance similar Exam 1. The operation process assessment included content from the Chinese Oral Physician Licensing Exam, such as supragingival scaling. The items and scoring standards are detailed in Table 1: preoperative preparation, operation posture, fulcrum, periodontal probe, and supragingival scaling. Table 1 Scaling operation score sheet.

Supragingival scaling effect
Supragingival scaling removes supragingival calculus, plaque, and color stains using various instruments. Since there was no calculus in the volunteers' mouths, we used the plaque index to assess supragingival scaling in our study. All of the 60 volunteers received periodontal scaling operating randomly by means of pairwise correlation. Then, the supragingival scaling score was calculated as a hundred mark system using the following equation: The Turesky modi cation of the Quigley-Hein index [20], was used to assess the supragingival plaque revealed on six sites (e.g., mesial buccal, median buccal, distal buccal, mesial lingual, median lingual, distal lingual) of each tooth [21] (Fig. 5C/D/E/F).

Questionnaire survey
At the end of the course, the students completed a satisfaction questionnaire-based evaluation using a 5point Likert scale (5 = strongly agree, 4 = agree, 3 = neither agree nor disagree, 2 = disagree, and 1 = strongly disagree) [22].

Statistics analysis
Data analysis was performed with the statistical software, SPSS for Windows version 20 (IBM Inc., Chicago, IL). A comparison of each four groups was done through ANOVA in case of data conformed normal distribution and homogeneous variance, if not, a non-parametric test was adopted. Differences between Exam 1 scores and Exam 2 scores were determined using a paired t-test operational assessment was subjected to an one-way ANOVA. Data are presented as the mean ± standard deviation (SD).
The second theoretical examination scores were signi cantly higher than the rst theoretical examination scores in each group. (V: 50.67 ± 3.72; J: 49.00 ± 4.31; V-J: 60.00 ± 4.47; J-V: 58.33 ± 4.35; P < 0.01, Fig. 4B/C). Additionally, the individual scores of students in groups V-J and J-V were signi cantly higher than those of students in the other two groups (P < 0.05, Fig. 4B/C). However, there was no signi cant differences in academic performance between students in Group V-J and Group J-V.

Operation assessment
The scoring key points of the actual operation procedure were judged by a professional (over 5 years . Additionally, the greatest e cacy is Group J-V (Fig. 5B). This nding suggests that initial training with the jaw model and subsequent virtual training strengthens students' performance on clinical competencies. Previous studies have explained that this phenomenon is due to students' abilities to purposefully and selectively master skills in virtual stimulation systems after jaw model training.

Questionnaire
According to the scores on the Student's Satisfaction Questionnaire, participants in Group V-J and Group J-V were highly satis ed with their training ( Table 2). The lowest scoring item in Group J was "Acquisition of knowledge," and only one-third of the students were satis ed. It is easy to understand virtual simulation system interacts with students strongly and simulates the clinical diagnosis and treatment process. The lowest scoring item in Group V was "Improvement of clinical skills," and 27% of the students were dissatis ed, and 40% chose "neither agree nor disagree." Therefore, virtual simulation systems may training lack concrete experience. The highest-rated scoring item in Group V-J and J-V groups are "Combine theory with practice." The training method of jaw model combined with virtual simulation system has achieved excellent results.

Discussion
The primary objective of this research was to explore themes related to periodontal operation in a medical clinical teaching unit, based on comparation the traditional jaw simulation and virtual simulation, seeking for higher e cient manner and avert shortcomings in traditional teaching methods allows the students quickly practice new skills lasting the same amount of time [23]. Our experimental results showed that no matter promote theoretical knowledge or acquisition of periodontal supragingival scaling of clinical skills, the combination of virtual simulation and jaw model both were superior to traditional teaching methods.
Our results also revealed that the order of the methods (i.e., J-V vs V-J in uenced the effectiveness of clinical teaching, and this was especially noticeable for the supragingival scaling procedure.
The transition of theoretical medicine into clinical practice is di cult, however, there is an urgent need for simulation training methods that integrate theory into practice [24]. In previous studies, they offered a means of role play the communication between physician and patient simulate on different clinical specialties largely boosted their memory of theoretical knowledge [25]. Consistent with our results of improved second theoretical scores. Murbay [26] assessed undergraduate performance by introducing a randomized setting in a Moog Simodont virtual system within the per-clinical stage and found that it signi cantly improved student's operation level. This type of training would be valuable for students in training programs and for undergraduate teaching. Another scholars have found that students successfully mastered tooth preparation skills using virtual simulation [27]. Further, de Boer IR [28] explained the possible causes which is force dependent feedback might practice hands agility more improve students' clinical skills when the time reached on enough time. Our experimental and modeling results are consistent with the hypothesis that virtual simulation is bene cial for operation ability. While a single training of virtual simulation cannot achieve the best effects because of differences in the system used, pro ciency of the system, and the particularity of dentistry [28,29].
Studies have reported that virtual technology offers multiple advantages in education, including improved e ciency and quality of study through feedback signals to the brain, su cient and free training time, and accurate and automatic training data [30]. However, some scholars believe that virtual technology should not be used as an alternative to traditional methods because of excessive critical feedback, lack of personal contact, and technical hardware di culties that are associated with VR-based training [31]. According to Plessas [32], the guidance and evaluation of professional teachers are still indispensable and virtual systems cannot fully replace traditional training courses. Furthermore, Al-Saud et al [33]. randomly divided 63 people without oral professional training into 3 groups: the Device Feedback group, the Instructor Feedback group, and the Instructor Device Feedback group and revealed that skills and error rate in the last group were improved as compared with those in the former two groups. This difference translates into improvements in skill retention and the extension of knowledge to new tasks. The combination of professional guidance and feedback from a virtual simulation system (e.g., VR) is best for junior students to learn and master basic oral operations, which is consistent with our research design and conclusions.
However, the optimal sequence for training with jaw model and virtual simulation system has not been determined. In this study, the best supragingival scaling effect was observed in Group J-V. Jaw model training provides students with concrete experience that allows them to strengthen their operating skills separately. Indeed, studies have reported differences in the levels of performance between novice students (< 1 year) and experienced dental students after training with virtual simulation systems, and current study revealed features that are unique to VR and that may help us understand how these characteristics impact dental education [34]. In addition, there are a small number of students whose theoretical grades does not match the operating scores. According to neurophysiological research, this discrepancy may be related to differences in personal psychomotor skills [35].
There are several strengths associated with this study. Our methodology and ndings address the shortcomings of VR periodontal education in the research literature, and may provide a useful reference for future medical teaching models. Furthermore, we cannot observe the therapeutic effects of subgingival scaling over a short period of time, and none of periodontitis patients do want to be treated by students. Hence, it was reasonable for us to explore the teaching method of periodontal operation by supragingival scaling. Most importantly, we used the Turesky modi cation of the Quigley-Hein plaque index gathering student's training outcomes instead of practical clinical operation direct to patients. This method can be used to assess the teaching effect of supragingival scaling. At the same time, plaque can be identi ed by its unique color which allows for thorough and accurate supragingival scaling.
The study also had multiple limitations. First, the approach we adopted was inevitably one-sided as compared with the general strategies that are used to evaluate periodontal treatment effects, such as probing depth and attachment loss. However, few patients allow undergraduate students to perform these procedures. Additionally, the training time of the experimental subjects may have not been su cient to fully predict the long-term application effect of the various teaching methods. Future studies will evaluate the long-term application effects of the virtual stimulation system, including the optimal application period in the teaching process. Further, there was a possibility of publication bias for different manipulation systems of VR [36]. Finally, it is necessary to develop more realistic virtual simulation equipment.

Conclusions
Our ndings indicate that a combination of VR and jaw model during periodontal pre-clinical training may improve students' grades and help them develop professional skills. More importantly, our results suggest that the jaw model should be applied prior to VR in order to assist students and optimize learning.

Declarations Acknowledgement
We would like to thank for all the student's wonderful cooperation. Availability of data and materials The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Ethics approval and consent to participate
This study was approved by Ethics Committee of the School of Stomatology Lanzhou University (No. LZUKQ-2019-25), and all students provided written informed consent to participate in this study. Besides, all the experiment protocol for involving humans was in accordance to Declaration of Helsinki.

Consent for publication
All participants provided informed consent for publication specially gure 2 and 3.

Figure 1
Flow chart of design