Effectiveness of haptic feedback devices in preclinical training of dental students—a systematic review

Background Acquisition of psychomotor skills is of utmost importance for competent preclinical restorative dentistry. Recent advancements in haptic feedback technology have been incorporated into preclinical dental education to augment the conventional phantom head-based training. Objective This systematic review aims to assess the effectiveness of haptic feedback device, Simodont, in improving the skill development and learning outcomes of dental students during their preclinical training. Materials and methods Electronic databases Web of Science, Scopus, PubMed were searched for relevant studies since inception up until March, 2023. Only English language studies that assessed the effectiveness of haptic feedback devices in preclinical dental education were included. We excluded studies that did not use Simodont as the haptic feedback device or did not involve preclinical restorative work. Study quality was assessed using the revised Cochrane risk of bias tool and ROBINS-I. The primary goal of the study is to evaluate the efficacy of Simodont as a complementary training modality for dentistry students. Results Results from 9 high-quality studies were analyzed and synthesized to evaluate the overall impact of haptic feedback devices on various aspects of preclinical training. The studies were conducted on 826 undergraduate dental students enrolled in various years of their training across dental colleges and universities in different parts of the world. A majority of studies showed some concerns regarding risk of bias. Haptic feedback devices added a new layer to Virtual Reality (VR) through the perception of touch and force feedback. It assisted junior dental students improve their psychomotor skills and movement skills. Instantaneous feedback on the students' performance helped enhance their self-assessment and correction, and also eliminated the subjectivity of evaluation. Data derived from virtual simulators helped stratify dental students and predict their clinical performance, providing an opportunity to tailor the learning process to meet individual diversity in students' expertise. Conclusion Based on the limited evidence available, Simodont was effective in preclinical training of dental students, offering advantages such as unlimited reproducibility, objective evaluation of preparation by computer assessment, and cost reduction. And further studies are warranted to explore the incorporation of patient's oral environment simulation for better skill training.


Introduction
Dentistry requires the development of precise manual dexterity.In contrast to many other health sciences disciplines, dentistry primarily focuses on practical applications, including the manual administration of restorative treatments.The primary focus and central competence of preclinical operative dentistry is the development of psychomotor abilities among dental students.This aspect receives the majority of curriculum time during the preclinical phase [1].
Students are often instructed on phantom heads in conventional preclinical training.Phantom head or mannequin training is a pedagogical strategy used in dental education that use a simulated human head or mannequin to give students with a safe and genuine environment in which to improve their procedural abilities.These training models are designed to mimic the physical characteristics and anatomy of a human head, including the teeth, gums, and jaw, allowing students to practice procedures such as tooth extraction, filling, and crown preparation.It allows students to practice their motor skills, develop their dexterity and hand-eye coordination, and improve their understanding of dental anatomy and oral physiology [2].However, it lack the realistic tactile sensations experienced during actual clinical procedures.Also, plastic teeth do not sufficiently replicate the variability of natural teeth and the significant accumulation of plastic waste associated with their use presents a substantial environmental concern.It is increasingly difficult to obtain natural human teeth due to ethical constraints [3][4][5].In conventional training, the assessment process often relies on the retrospective evaluation of a student's skill and practises after their training sessions.This disparity between preclinical simulation and real-world practice can lead to challenges for students when they transition to treating real patients [6][7][8].
The integration of haptic feedback technology in dental education aligns with the evolving educational landscape, emphasizing evidence-based approaches and technology-driven pedagogy.Haptic feedback devices have been proposed as a complementary modality for conventional preclinical training methods, such as working with mannequins or extracted teeth [9].Haptic technology, also referred to as kinaesthetic communication, is capable of eliciting a proprioceptive response through the use of vibration and force in coordination with physiological motions.This form of training provides dental students with the opportunity to practise procedures on virtual patients using haptic simulators that provide realistic tactile force feedback.The Force Feedback is a cuttingedge technology that revolutionizes dental training.It employs haptic feedback to provide realistic tactile sensations during virtual dental procedures.When a student interacts with the virtual tooth using a dental instrument, the haptic device generates force feedback that simulates the resistance and pressure experienced in real-life clinical settings.This dynamic feedback allows students to develop and refine their motor skills, hand-eye coordination, and dexterity while performing various dental tasks [10].
Haptics dental suites displays the tooth and the instrument in three-dimensions in true size on screen.The tooth is presented digitally as a series of voxels of varying density [11].Each point on the tooth reacts differently to the contact of a drill, with force being transmitted through the haptic device to the user.The force transmitted is proportional to density values of each voxel that makes up the three-dimensional tooth [12].The user can receive different force feedback depending on the tooth and angle of the tooth, resembling a real-life clinical situation.Haptic technology is used with many phantom heads and mannequins to simulate working with real dental instruments and materials, giving students a more realistic and effective training experience [13].The ability to practise operations indefinitely in a safe and controlled environment without the risk of harming a living patient is a major advantage of haptic-based training [14].The use of haptic technology in dental education has been shown to improve student's motor skills and increase their confidence in performing procedures in a clinical setting [10,15].
Simodont is a dental training simulator that utilizes haptic technology to provide realistic tactile feedback while performing virtual dental procedures [16].Simodont training system is widely used in dental schools and training centers around the world.The system can be customized to simulate various dental procedures and conditions, providing students with a comprehensive and immersive educational experience [17].The system utilizes advanced sensors and algorithms to track and analyze a variety of parameters such as the pressure and angle of the instrument, the speed and trajectory of movement, and the duration of the procedure [18].The system can supervise a student's preclinical work, identifying if a student is working on the wrong tooth or inadvertently inflicting damage to the virtual gums or other soft tissues.This data is used to provide personalised feedback to the student, such as identifying areas where they may be applying too much or too little pressure, or where they may be deviating from the proper trajectory.This feedback can be customized to the individual student's needs and skill level, providing a more efficient and effective learning experience [19].
Few published studies have systematically examined the effectiveness of preclinical haptic dental training of undergraduate students [20,21].Existing knowledge regarding virtual training primarily focuses on the assessment of augmented reality or virtual reality systems, with limited systematic reviews delving into a comprehensive analysis of a singular haptic dental device specifically designed for preclinical training of dental students.The objective of this study was to investigate the impact of haptic feedback devices on the development and acquisition of psychomotor skills in dental students during preclinical training by analysing current literature, which included both experimental and observational studies.

Search strategy
This systematic review was conducted in accordance with the guidelines outlined in the Preferred Reporting for Systematic Reviews and Meta-analysis (PRISMA) statement [22].
The focused question was "Are Simodont haptic feedback devices effective in the clinical training of dental students?".
Inclusion criteria consists of undergraduate dental students from all over the world who are in different stages of their training and come from different dental colleges and universities.In our study, the intervention is the use of haptic feedback devices, like the Simodont haptic training system, for preclinical training of dental students.The comparison group is made up of students who do their preclinical training without using haptic feedback devices.

Exclusion criteria
Case reports, conference proceedings, systematic reviews, opinion articles, letters to the editor, case reports and articles in languages other than English were excluded.

Search strategy and study selection
A comprehensive search was conducted on electronic databases including Pubmed, Scopus, and Web of Science.The search query for PubMed included a combination of Medical Subject Headings (MeSH) terms and relevant keywords related to haptic interfaces and technology, dental students, and Simodont.The search strategy for Scopus included a combination of relevant terms related to haptic technology, dental training, and Simodont; whereas for Web of Science, the search query combined the keywords "haptic" and "dental students".The search was limited to papers published in the English language, with no constraints imposed on the start date.The search was performed in March 2023.After executing the search queries, a total of 64 articles were retrieved from PubMed, 3 articles from Scopus, and 17 articles from Web of Science.Details of the search strategy are provided in Table 1.The first screening of search results for study selection was carried out by two independent reviewers (SP and MDB), who removed duplicates and non-relevant publications.Subsequently, titles and abstracts of studies were screened to determine their eligibility, and discrepancies were resolved through consensus with a third author.Subsequently, full-text review of the shortlisted studies was conducted based on predefined inclusion criteria, and a third author (XZ) was consulted for the final decision in case of any contention.Furthermore, manual supplementary searches were conducted on references of the selected articles in order to identify any additional eligible studies.The details of the selected studies are provided in Table 2.

Data extraction
The data extraction form used in this systematic review was developed based key attributes and characteristics that were relevant to our research, including study details (e.g., authors, publication year, country of origin), study population (e.g., dental students' stage of training, institution), intervention details (e.g., type of haptic technology used, duration of training), and outcome measures (e.g., assessment of psychomotor skills, clinical performance).Additionally, we included specific criteria for assessing the risk of bias in the included studies.The process of data extraction from the shortlisted studies was conducted by two reviewers (XX and XX) who worked independently.To ensure the correctness of the extracted data, a third author (XX) validated the results.The pertinent attributes of the studies that were included, such as the names of the authors, the year of publication, the country of origin, the methodological details the sample size, the treatment regimen, and the duration, were manually extracted and recorded in a customised template.

Assessment of study quality
The quality of the selected studies was by two reviewers (SP and FL) individually.They assessed the risk of bias for randomized studies using the revised Cochrane Risk of Bias tools for randomised trials (RoB-2) and nonrandomized controlled studies using the Risk of Bias in Non-randomised Studies of interventions (ROBINS-I) tool [32,33].Any disagreements between the reviewers were resolved through discussion or by consulting a third reviewer (GM).
RoB-2 was used to assess the risk of bias in studies by assessing five domains: bias arising from the randomization process, bias due to deviations from intended interventions, bias due to missing outcome data, bias in the measurement of the outcome, and bias in the selection of reported results.Each domain was evaluated through a set of signaling questions to identify potential sources of bias in the study.The responses to the signaling questions were used to assign a judgment of low, high, or some concerns regarding the risk of bias for each domain.
In ROBINS-I, signaling questions focusing on seven domains during pre-intervention, at-intervention, and post-intervention, were used to evaluate the studies.The evaluated domains encompass confounding variables, participant selection, intervention classification, deviations from intended interventions, missing data, outcome measurement, and selection of reported results.For each domain, specific criteria are used to evaluate the risk of bias, and the overall risk of bias is rated as low, moderate, serious, or critical.

Quality of evidence for outcomes in Summary of Findings table
The GRADE evidence grading system, which is described in Sect.12.2 of the Cochrane Handbook for Systematic Reviews of Interventions, was used to rate the quality of the evidence for each outcome in the Summary of Findings [32].One of the authors used the GRADE system, and subsequently discussed with the other two authors to reach a consensus on the quality of evidence for each outcome.The criteria used for downgrading the quality of evidence included five domains: risk of bias, inconsistency of results, indirectness of the evidence, imprecision of the results, and publication bias.

Results
We found 103 results in our first pass through the database searches.After removing 38 duplicates, the remaining papers were screened on the basis of title and abstract for eligibility.Sixteen full-length papers were obtained for assessment.Citation searching of papers led to an additional four papers.Finally, nine articles published between the years 2017 and 2023 were included in the present review [23][24][25][26][27][28][29][30][31].The PRISMA flow diagram is shown in Fig. 1.

Quality assessment
Most studies have considerable problems owing to unclear and insufficient reporting.Three out of nine studies showed a high risk of bias, while six studies, including three randomised trials, showed some concerns.Poorly  reported items across the studies included sample size calculation and report of losses to follow up, raising apprehension about reliability and validity reflected in the higher risk of bias ratings.A summary of the risk of bias assessment is shown in Figs. 2 and 3 [34].

Quality of evidence for outcomes in Summary of Findings table
Low-certainty evidence implies that Simodont training may have a favourable impact on dental students' psychomotor skill acquisition and development, enhancing motor abilities, manual dexterity, and clinical performance when compared to traditional training.The evidence was downgraded by two steps, due to bias and the fact that majority of the studies were non-randomised.The summary of findings is shown in Table 3.

Characteristics of the selected studies Study population and setting
The participant demographics and study settings varied, encompassing undergraduate dental students at different stages of their training and institutions located across different regions of the world.The studies were conducted on undergraduate dental students enrolled on the dentistry programme in their first [23,24,26,28,29], second [25,27], third [24,29,31], fourth [24], fifth [24] and sixth [30] years of training.All the studies took place at various dental colleges and universities across the world with a majority being done in Europe (UK [24,25,28], Netherlands [23,26]) and Asia (Hong Kong [27], Spain [29], Japan [30], and Saudi Arabia [31]).

Duration
The study duration varied from practically no pretraining to an exercise period of fifteen minutes to a longitudinal study where students who completed the first year were followed for 2 years and re-evaluated in the third year [24,28,29].Another study followed up with students in their 2 nd year to 2 years later when they performed on patients [25].

Pre-training
The duration and intensity of practice varied across studies, with some studies incorporating short practice sessions while others implemented longer and more extensive practice periods.Hattori et al. gave the participants free practice time of 10 min to become acquainted with the device, followed by crown preparation [30].
Farag and Hashem permitted the the students to practise for 20 min per day for four weeks [31].De Boer et al. allowed participants to practice for three months with a standard amount of force feedback (FFB) to enhance their fine motor skills [26].In another study students underwent four sessions of 45 min each before their test session [23].

Outcome measure assessment
Seven out of the nine studies measured the efficacy of Simodont in restorative work either by operating on the standard caries removal protocol or the cutting of some form of geometric shape [23-27, 29, 31].Real time feedback on performance was presented on a computer monitor which was assessed by experienced trainers [23][24][25][26][27][29][30][31].For a few studies the conventional simulator preparations were compared to those done using simodont [25,27,31].Studies used various factors for evaluation such as target, error scores, drill time [24] or procedures done at different levels of force feedback [23,26].One study compared work done on the Simodont by experienced clinicians to that done by dental students [28].Two studies measured the efficacy of Simodont in crown preparation [25,30].Their performance on patients was compared to their performance in VR and the conventional typodont 2 years prior [25].Scores for preparations of the occlusal surface, margin design, surface smoothness, taper angle, total cut volume and overall impression of the products for both the conventional simulator and Simodont were compared [30].

Effect of intervention
Nine studies were reviewed to evaluate the heterogeneity of results and to determine if Simodont is a valid tool for preclinical undergraduate education.Out of the nine studies, eight reported that Simodont is a valid tool for training dental students [23][24][25][26][27][28][29]31], while Hattori et al.reported lower scores for students performing tooth preparation using the haptic simulator compared to the conventional method [30].
Studies found that the effect of force feedback was important in achieving high precision tasks in dentistry.Students practicing with the effect of force feedback outperformed those practicing without it [23].Manual dexterity skill was found to be transferable from one level of force feedback to another if the students practiced for a  sufficient amount of time [26].On comparing work done by experienced and novice students the authors reported that Simodont showed sensitivity to performance differences between the two thus can be used for measuring dental performance and student education [24].Studies comparing performance on conventional simulators versus haptic simulators showed that incorporating Simodont training would be a valuable adjunct in dental education [25,27,29,31].

Discussion
Haptic feedback devices have emerged as valuable tools in dental education, offering a three-dimensional virtual reality environment that replicates real dental settings.This controlled environment allows students to practice diverse dental procedures, and their effectiveness in preclinical training has been an ongoing subject of research and discussion [23-28, 31, 35, 36].Through a comprehensive analysis of nine selected studies, this systematic review focused on assessing the impact of adopting Simodont in preclinical dental training, with a particular emphasis on the development of psychomotor skills, motor skills, manual dexterity, and clinical performance.
Studies reported that Simodont assisted in the acquisition and retention of fundamental psychomotor abilities needed for performing operative dentistry, particularly when combined with instructor feedback [25].However, it's worth noting that not all studies were unanimous in their support for haptic simulators, with some reporting lower scores compared to conventional training for specific evaluation items.The differences in hand manipulation during preclinical procedures in the simulators may have contributed to the differences in students' performance.Furthermore, individual differences in the depth perception ability and different retinal disparities may also have lead students to find depth perception difficult in the simulator [30].The distinctive attributes of Simodont such as the generation of three-dimensional images through stereo viewers, have a discernible impact on the performance of operators and the perception of evaluators.Hence, it is imperative to design curriculum that takes into account such features offered by each simulator [30].Overall, majority of studies reported the positive potential of Simodont as a valid tool for enhancing motor skills, manual dexterity, and clinical performance [23,24,[26][27][28]31].
The force feedback feature in haptic technology emerged as a critical aspect, enabling students to achieve the high precision levels necessary for manual dexterity tasks in dentistry [23].Skills learned in virtual reality (VR) can be translated to real-world situations when students practise for long enough at one level of force feedback and then go on to the next [26].
The continuous evaluation of students using haptic simulators, along with sensory feedback during the preparation of enamel and dentine, enhanced hand-eye coordination and fine psychomotor control, thereby improving their psychomotor skills [31].Simulation exercises were particularly valuable in assessing the students' grasp of the concept of caries removal [28].The results provide important implications for the use of Simodont in preclinical training of dental students.The sensitivity of Simodont in detecting performance differences between novice and experienced students suggests that it is a useful tool for measuring dental performance and student education [24].
Simodont's advantages could extend beyond the technical aspects, as it has the potential to reduce anxiety levels among dental students.The immediate feedback provided by haptic devices promotes self-assessment, allowing students to identify areas for improvement [37,38].Moreover, the ability to repeat procedures on haptic devices until acceptable skill levels are demonstrated without risking actual patients, can improve student confidence and competence and help in facilitating patient safety.Ethical decision-making training offered by Simodont enables students to navigate complex patient situations responsibly and ethically, enhancing overall patient care.This type of training provides unlimited reproducibility, objective evaluation of preparation by computer assessment, and cost reduction.It also narrows down the gap between preclinical and clinical skill levels [39].Overall, Simodont proved efficient in training dental students in hand-eye coordination and spatial reasoning skills, improving preparation accuracy and shortening preparation time [40][41][42][43][44].
Multiple studies have reported that instantaneous feedback on student performance improved self-assessment, adaptation and eliminated subjectivity [40][41][42].This finding corroborates earlier findings by Vincent et al.where haptic simulators could monitor and guide the progression of novices during cavity preparation [45]; though the role of teacher and verbal instructions cannot be ruled out [36].VR simulators have become popular due to their ability to provide high-quality education, decrease inequality, and reduce waste [46].However, patient oral environments of gingival tissues, saliva, tongue movements, and reflexes, such as gagging, cough, and head movement simulation, still need to be incorporated for better skill training and teaching emergency management [47].
It is recommended that students practice for a sufficient amount of time to ensure transferability of the skill in real-life situations.Urbankova et al. suggested that eight hours of computerized dental simulation training delivered early in the preclinical operative dentistry course is required to improve students' performance [48].Data from virtual simulators can help stratify dental students and predict their clinical performance, providing an opportunity to tailor the learning process to meet individual diversity in students' expertise and allow students to work at their own pace, thus helping them reach optimal performance [36].
A major strength of this review is the comprehensive search strategy, which aimed to identify all relevant studies on virtual Objective Structured Clinical Examination (OSCE) in dental education.The use of two independent reviewers in study selection, data extraction, and quality assessment also enhances the reliability of the findings.However, the review also has several limitations that need to be considered.The number of studies included in the review is relatively small, and the sample sizes of the individual studies are generally low, which may affect the generalizability of the findings.Additionally, the study designs and assessment methods used in the included studies were not standardized, which limits the ability to draw definitive conclusions.The studies included in the review also had a moderate to serious risk of bias, which may affect the validity of the findings.Furthermore, the review only focused on Simodont in dental education, limiting the generalizability of the findings to other haptic training devices.Given the limited availability of data, these results warrant cautious interpretation.A majority of studies were conducted in first world countries with no studies conducted in lower and middle-income countries (LMICs) where where infrastructural resources may be relatively scarce.Hence, larger datasets are required to validate and replicate these findings, which could potentially contribute to the assessment, design, and targeting of haptic interventions.
Overall, Simodont has the potential to be an effective and accepted adjunctive training method in dental education, but further research is needed to determine its full impact.Overall, our review addresses the need for dental educators to adopt new and innovative methods of teaching preclinical skills to dental students, and provides valuable insights into the potential benefits of haptic feedback devices in this regard.The findings of this review may inform educators and policymakers about the potential benefits of Simodont haptic feedback devices as a teaching tool for preclinical dental training.The incorporation of Simodont can bridge the gap between preclinical simulation and real-world clinical practice, enhancing the preparation of dental students for patient care.Given the potential benefits and positive outcomes observed in the selected studies, further research, and collaboration between dental educators and Simodont developers are essential to maximize the impact of this technology on dental education and, ultimately, improve patient outcomes [49][50][51][52][53][54][55][56][57].

Conclusions
This systematic review evaluated the effectiveness of Simodont in the preclinical training of dental students.Based on the limited evidence available, there is low-certainty evidence that Simodont is effective in improving the motor skills, manual dexterity, and clinical performance of dental students.The effect of force feedback feature is important to acquire manual skills and if practised for long enough these skills can be transferred to reality.While acknowledging the limitations in reporting and study designs, the majority of the reviewed studies highlight the value of Simodont in preclinical dental education.However, well-planned highquality studies with larger sample sizes are required for further evaluation of the assessment methods.

Fig. 2
Fig. 2 Summary of risk of bias assessment for randomised studies (RoB-2)

Fig. 3
Fig. 3 Summary of risk of bias assessment for non-randomised studies (ROBINS-I)

Table 1
Search strategy dental"[MeSH Terms] OR ("students"[All Fields] AND "dental"[All Fields]) OR "dental students"[All Fields] OR ("dental"[All Fields] AND "student"[All Fields]) OR "dental student"[All Fields]) 19 Scopus TITLE-ABS-KEY ( Haptic AND dental AND training) 3 Web of Science Haptic (All Fields) and dental students (All Fields)

Table 2
Characteristics of the selected studies

Table 3
Summary of findings tablea Three showed high risk of bias; six studies were rated to have some concerns