Effect of different finishing and polishing systems on surface properties of universal single shade resin-based composites.

BACKGROUND: Recently, universal single-shade resin composites have become increasingly available in the dental market. The modification of their composition can have an inadvertent effect on their physical and surface properties, and subsequently determinantal effect on their clinical function and longevity. Therefore, this study aimed to evaluate the effect of different finishing and polishing (F/P) systems on surface roughness (Ra), surface gloss (GU), and Vickers microhardness (VMH) of universal single-shade RBCs. MATERIALS AND METHODS: Four commercial RBCs were used; the universal single-shade RBCs were Omnichroma, Charisma® Diamond ONE, and Vittra APS Unique, and a conventional nanocomposite Filtek™ Z250 XT was used as a control. The 3 F/P systems were Sof-Lex™ XT, Enhance®/PoGo®, and Diacomp® Plus Twist. A total of 160 discs were used for the 3 F/P system groups for all RBCs (n = 10). After F/P, the Ra, GU, and VMH were assessed. The data were analyzed using 2-way ANOVA at p-value < 0.05. RESULTS: Significant differences were found among the four RBCs and the 3 F/P systems (p < .000). Omnichroma showed the lowest Ra and acceptable GU, but the lowest VMH. Charisma showed the highest Ra, acceptable GU, and VMH. Vittra showed acceptable Ra, GU, and VMH and Filtek showed the highest GU, VMH, and acceptable Ra. CONCLUSION: Although conventional nanohybrid RBC (Filtek Z250 XT) showed better GU and VMH values, the universal single-shade RBCs demonstrated comparable surface properties. The highest GU & VMH and lowest Ra were achieved by Diacomp followed by Enhance and Soflex.

The effect of instructional methods on dental students' performance in a preclinical endodontic course: A comparative ambispective cohort study.

OBJECTIVE: The aim of this ambispective cohort study was to examine the effect of instructional methods on dental students' performance in a preclinical endodontic course. Two cohorts of undergraduate students were included. The pre-pandemic (retrospective) cohort, which had been taught via traditional instruction (live lecture and live demonstration), and the pandemic (prospective) cohort group, which had been taught via a blended learning approach (online/video recorded lecture and video demonstration, combined with practical training in the simulation laboratory). METHODS: A total of 263 dental students' competencies and written exam results were reviewed, with 137 students from the traditional and 126 from the blended learning groups. Students' performances in the competency practical and written exams for both groups were compared. Additionally, a post-course survey was designed to explore the students' perceptions of blended learning and was sent to the blended learning cohort. RESULTS: There was a statistically significant difference between both groups in students' weekly practical project scores. The average score for females was significantly higher than that of males. However, their practical competency exam scores were comparable. On the other hand, the written exam scores were significantly higher in the blended than in the traditional group, with females demonstrating significantly higher written exam scores compared to males (p < 0.001). CONCLUSION: Blended learning is an effective teaching method for preclinical endodontic courses. It could be more useful than traditional learning methods for the course's theoretical content. Additionally, the students preferred to continue learning using this model.

Simulated skill complexity and perceived cognitive load during preclinical dental training.

INTRODUCTION: Cognitive Load theory (CLT) focuses on the information processing aspect of learning and how the working memory handles the mental effort associated with new task. The aim of this study is to investigate the association between the perceived cognitive load and performance amongst dental students during preclinical simulation training at various levels of procedural task complexity. Additionally, some cognitive load-modifying factors were examined. MATERIALS AND METHODS: This cross-sectional study evaluated the perceived cognitive load amongst second-year dental students (n = 34), using the validated National Aeronautics and Space Administration's Task Load Index (NASA TLX index) after training on four dental tasks at two levels of complexity, in addition to structured online anonymous questionnaire about demographics, feedback and performance. The NASA TLX raw scores and the weighted global score were calculated for each exercise. Descriptive statistics and Pearson's correlations between performance and the corresponding NASA TLX-weighted score were calculated. Mean differences in the perceived cognitive load across the exercise levels were assessed using RM-ANOVA with Bonferroni corrections at p < .05. RESULTS: Reduced performance was significantly associated with higher cognitive load particularly in high complexity dental task (class II-mirror vision). Simulated exercise complexity significantly influenced the students' perceived mental demand, physical demand and temporal demand; all were significantly higher for class II- mirror vision task than for direct vision tasks. The majority of participants (82.1%) preferred detailed feedback from instructors, and more than half of the participants (60.7%) preferred continuous feedback throughout the training session. CONCLUSION: Complex dental tasks are associated with higher cognitive load in novice dental students during preclinical training. The NASA TLX index is a useful instrument to explore the level of perceived cognitive load associated with performance of simulated complex dental skills. Cognitive load theory is relevant to simulation-based dental education to improve the preclinical instructional efficiency and to enhance students learning.

Do Self-adhesive Resin Composites Release More Monomers? A Comparative High-performance Liquid Chromatographic Analysis.

PURPOSE: To comparatively evaluate the elution of residual monomers (bis-GMA, bis-EMA, TEG-DMA, and HEMA) from two self-adhesive flowable resin composites, a giomer, and a nano-flowable resin composite over five different time intervals, using high-performance liquid chromatography (HPLC). MATERIALS AND METHODS: Four flowable resin composites were investigated (Vertise Flow, Constic, Beautifil Flow Plus F03, and Filtek Z350 XT). Immediately after polymerization, each sample was immersed in 75% ethanol/water solution and stored in amber-colored bottles at room temperature. HPLC analysis was performed at predefined time intervals: 1 h, 24 h, 4 days, 8 days and 16 days. The extraction solution was changed after each analysis. Data were analyzed with repeated-measures ANOVA and one-way ANOVA with Tukey's post-hoc test at p < 0.05. RESULTS: The highest mean concentration of residual monomers was eluted from Beautifil, followed by Filtek, and both were significantly higher (p < 0.05) than the mean concentration of eluates from self-adhesive resin composites (Vertise Flow and Constic). Vertise Flow released significantly higher concentrations of HEMA than all the other tested materials. At 1 h post-immersion, 52.2% of monomers were eluted, and continued to elute at a reduced rate throughout the study duration. TEG-DMA was the fastest monomer to leach out, while bis-GMA exhibited significantly higher total mean concentration. The elution rate was significantly dependent on the molecular weight of the eluted monomers. CONCLUSION: No specific elution behavior can be attributed to self-adhesive RBCs. Elution of residual monomers is dependent on each material's composition, resin matrix characteristics, and the monomer's molecular weight.

Comparative evaluation of Rheological characteristics of Giomers and other Nano-flowable resin composites in vitro.

OBJECTIVE: The purpose of this research was to determine the viscoelastic properties of a group of commercially available nano-flowable resin composites; and to explore the relation between these properties and the materials' composition (with/without fluoride), filler size description (nano-filled, nanohybrid and submicron-filled) and filler loading (by volume). METHODS: Rheological measurements were performed using a rheometer. A Dynamic frequency sweep test was conducted to evaluate the complex viscosity, storage and loss moduli, loss tangent, and complex shear modulus at an angular frequency (ω) of 0.1-100 rad/s. Comparative evaluations of the nano flowable resin composites on rheological properties was performed, and statistically analyzed using one-way ANOVA. RESULTS: The results indicated that all the tested materials exhibited shear-thinning flow behaviour. As the shear rate increased, the complex viscosity of the nano-flowable composites decreased. The nanohybrid filled flowable resin composites exhibited the highest complex viscosity, while the nano-filled flowable resin composites exhibited the lowest value. The submicron-filled materials exhibited the lowest complex shear moduli and loss tangent values. Conclusions: The findings from the current study provided comprehensive evaluation of the rheological properties of different nano-flowable composites. The observed differences in rheological properties among the tested materials were independent of their fluoride content or filler size. Furthermore, no relationship was found between the complex viscosity of the tested nano-flowable resin composites and their filler volume.

The utility of haptic simulation in early restorative dental training: A scoping review.

BACKGROUND: Haptic dental simulators are becoming increasingly available in dental schools around the world; however, there is a paucity of evidence on their pedagogical effectiveness particularly in early dental training for the acquisition of the highly specific fine motor dental skills. METHODS: A scoping review was performed to broadly map the available evidence and to detect knowledge gaps on the utility of haptic dental simulation in early dental training. The review is reported using the PRISMA-ScR guidelines. Eight bibliographic databases were searched: Web of Science, Scopus, MEDLINE via PubMed, Cochrane library, CENTRAL, ERIC, IEEE Xplore, and TRIP. Charted data were reported by clustering results according to study characteristics, research themes, research purpose, and type of validity evidence identified. RESULTS: The review process resulted in the inclusion of 36 studies published between 2009 and 2020. The majority of the studies were cross-sectional in design with short-term evaluation data. Of the studies included, 64% investigated commercially available haptic simulators, while 36% investigated experimental haptic simulators. The research themes identified were skill acquisition and transfer, task-specific haptic training, trainee level discrimination, feedback, subjective user evaluation, performance prediction, and human factors in haptic training. CONCLUSION: Short-term evaluation evidence from reviewed studies indicates the usefulness of the haptic simulators in early dental training. They complement the existing phantom head simulators by offering qualitatively different features. Further empirical research is needed to investigate the long-term impact of training with haptic dental simulators, to improve the availability of validation evidence and to enhance the results generalizability.

Early assessment with a virtual reality haptic simulator predicts performance in clinical practice.

Background: Prediction of clinical training aptitude in medicine and dentistry is largely driven by measures of a student's intellectual capabilities. The measurement of sensorimotor ability has lagged behind, despite being a key constraint for safe and efficient practice in procedure-based medical specialties. Virtual reality (VR) haptic simulators, systems able to provide objective measures of sensorimotor performance, are beginning to establish their utility in facilitating sensorimotor skill acquisition, and it is possible that they may also inform the prediction of clinical performance. Methods: A retrospective cohort study examined the relationship between student performance on a haptic VR simulator in the second year of undergraduate dental study with subsequent clinic performance involving patients 2 years later. The predictive ability was tested against a phantom-head crown test (a traditional preclinical dental assessment, in the third year of study). Results: VR scores averaged across the year explained 14% of variance in clinic performance, while the traditional test explained 5%. Students who scored highly on this averaged measure were ~10 times more likely to be high performers in the clinical crown test. Exploratory analysis indicated that single-trial VR scores did not correlate with real-world performance, but the relationship was statistically significant and strongest in the first half of the year and weakened over time. Conclusions: The data demonstrate the potential of a VR haptic simulator to predict clinical performance and open up the possibility of taking a data-driven approach to identifying individuals who could benefit from support in the early stages of training.

Drilling into the functional significance of stereopsis: the impact of stereoscopic information on surgical performance.

PURPOSE: One suggested advantage of human binocular vision is the facilitation of sophisticated motor control behaviours via stereopsis - but little empirical evidence exists to support this suggestion. We examined the functional significance of stereopsis by exploring whether stereopsis is used to perform a highly skilled real-world motor task essential for the occupational practice of dentistry. METHODS: We used a high fidelity virtual reality simulator to study how dentists' performance is affected by the removal of horizontal retinal image disparities under direct and indirect (mirror) observation. Thirteen qualified dentists performed a total of four different dental tasks under non-stereoscopic and stereoscopic vision conditions, with two levels of task complexity (direct and indirect observation) using a virtual reality dental simulator. RESULTS: Depth related errors were significantly higher under non-stereoscopic viewing but lateral errors did not differ between conditions. Indirect observation led to participants drilling less of the target area compared to direct viewing, but this did not interact with the stereopsis manipulation. CONCLUSIONS: The data confirm that dental practitioners use stereopsis and its presence results in improved dental performance. It remains to be determined whether individuals with stereo-deficits can compensate adequately. Nevertheless, these findings suggest an important role for stereopsis within at least one occupation and justify the design of simulators with 3D displays.