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ABSTRACT Objective Méthodology Résults Conclusion Prosthetic restorations require functional occlusal planes to ensure therapeutic success. The purpose of the present study was to develop a new Broadrick flag support for a semi‐adjustable articulator and to investigate the effectiveness of occlusal planes drawn using the Broadrick flag method by inexperienced practitioners in complex situations such as skeletal class II relationships associated with edentulous areas.The Broadrick flag support was designed and manufactured by the additive technique and was adapted to the Quick Master articulator. The QR code of the manufacturing file of the Broadrick flag support is accessible to any practitioner. Thirty‐seven third‐year students (inexperienced practitioners) were randomised into two groups for drawing occlusal planes on two models either with or without the Broadrick flag method. A prosthodontic professor (experienced practitioner) drew occlusal planes on the models to serve as references. Each model was analysed using a standardised method to measure the distances between the occlusal planes drawn by experienced and inexperienced practitioners.Only the distance measured for the right second molar of the first model with the Broadrick flag method was significantly shorter than those measured without using this method (p < 0.05, Wilcoxon test). Visual observations showed that only the second molar drawings of the inexperienced practitioners were above the drawings of the experienced practitioner.The Broadrick flag method helped inexperienced practitioners to draw occlusal planes of models in complex skeletal class II relationships associated with edentulous areas with natural teeth located both anterior and posterior to them. [ABSTRACT FROM AUTHOR]

Introduction: Acquiring insights into the framework design of metal‐based removable partial dentures (mRPD) is a current challenge in dental education. The aim of the present study was to explore the effectiveness of a novel 3D simulation tool to teach designing mRPD by investigating the learning gain and the acceptance and motivation towards the tool of dental students. Materials and Methods: A 3D tool based on 74 clinical scenarios was developed for teaching the design of mRPD. Fifty‐three third year dental students were randomly divided into two groups, with the experimental group (n = 26) having access to the tool during 1 week while the control group (n = 27) had no access. Quantitative analysis was based on a pre‐ and post‐test in order to evaluate the learning gain, technology acceptance and motivation towards using the tool. Moreover, qualitative data was collected by means of an interview and focus group to get additional insights into the quantitative results. Results: Although the results showed a higher learning gain for students in the experimental condition, the study did not find a significant difference between both conditions based on quantitative results. However, during the focus groups, all students of the experimental group revealed that the 3D tool improved their understanding of mRPD biomechanics. Moreover, survey results revealed that students positively evaluated the perceived usefulness and ease of use of the tool and indicated to have the intention to use the tool in the future. Suggestions were made for a redesign (e.g. creating scenarios themselves) and further implementation of the tool (e.g. analysing the scenarios in pairs or small groups). Conclusion: First results of the evaluation of the new 3D tool for teaching the design framework of mRPD are promising. Further research based on the design‐based research methodology is needed to investigate the effects of the redesign on motivation and learning gain. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to evaluate the influence of height and length variations of alumina ceramics manufactured by stereolithography on deformations caused by the manufacturing process and on the 3D shrinkage ratio to control the final dimensions and improve the adaptation of stereolithographic ceramic dental prostheses. Two different U-shaped models were designed with variable heights or lengths. The specimens were manufactured by stereolithography and were scanned using a microtomographic device before and after the heat treatment. Dimensional variations were measured using inspection software. The number and surface of layers of alumina ceramic influenced the reliability of the stereolithography manufacturing but did not influence the 3D shrinkage ratio. The larger the layer surface, the larger the deformation of the ceramic. Dental ceramics manufactured by stereolithography with smallest layer surface are the most reliable. This helps in the selection of the build orientation. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate two agents for bonding denture bases and teeth manufactured either by stereolithography (SLA) or by the subtractive mixed technique. Methods: Two types of cylinders [small for the tooth resin and large for the base resin) were designed using CAD software according to the ANSI/ADA 15-2008 (R2013)] specification. For SLA manufacturing, 30 small cylinders were shaped with Denture Teeth resin and 30 large cylinders with Denture Base resin. For the mixed technique, 30 large cylinders were manufactured by SLA with V-print dentbase resin, and 30 small cylinders were milled with a CediTEC DT disk. Half the specimens were bonded with liquid Denture Base resin and half with CediTEC Primer and Adhesive, according to the manufacturers' protocols. Shear bond strength was measured using a universal testing machine. The failure mode was noted for all the specimens. Results: The shear bond strength values were not significantly different between the groups (P> 0.05). Specimens bonded with liquid Denture Base resin displayed cohesive failure (P> 0.05, Χ²= 0). Of the specimens bonded with CediTEC Primer and Adhesive, cohesive failures were observed with five specimens manufactured with the SLA technique and one specimen manufactured with the mixed technique (P> 0.05, Χ²= 3.33). The Chi-square test results were significant between groups with different bonding agents regardless of the technique used (P< 0.001). Within the limitations of the present study, even if the shear bond strength values were similar, the failure mode analysis suggests that the uncured liquid Denture Base resin may be more effective than the CediTEC Primer and Adhesive for bonding denture bases and teeth manufactured either by SLA or the mixed technique. [ABSTRACT FROM AUTHOR]

Purpose: This in vitro study evaluated the effect of sodium carbonate (Na2CO3) concentration on adhesion between two layers of irreversible hydrocolloid wash impression material. Methods: The first layer of irreversible hydrocolloid was brushed with three concentrations (0.1, 0.7, or 7.0 wt.%) of Na2CO.3. Irreversible hydrocolloid not brushed with Na2CO3 was used as a negative control. Adhesion between the two layers (bond strength and adhesion energy) was then evaluated using a traction test, and the fracture modes were identified. The results of traction test were analyzed with a one-way ANOVA followed by a Tukey post hoc test. Chi-square test was used for analyzed failure mode after testing (a= 0.05). Results: The bond strength (0.0340±005 MPa) and adhesion energy (60.240 *12.817 J.m-2) of the 0.7% Na2CO3 group were significantly higher than those of the other groups (P< 0.05). The 0.7% Na2CO3 group displayed only cohesive failure (x²= 16; P< 0.0001). [ABSTRACT FROM AUTHOR]

Objectives: An innovative calibrated bur, aiming to improve precision during reduction of the incisal edge, was recently proposed to guide practitioners during tooth preparation. However, limited information is available concerning its usefulness in dental preclinical education. The aim of this study was to evaluate whether using this innovative guided bur improves learning experience quality and the performance of students during tooth preparation. Material and methods: After having provided written consent, 60 second‐year students were divided into two groups. One group used a 1‐mm rounded bur to perform depth grooves, whereas the second group used the innovative guided bur, consisting in a 2‐mm‐depth marker with a stopping surface. Once the grooves were obtained, they were then connected using the same wheel bur in both groups. The aim was to obtain a final 2‐mm reduction of the incisal edge. Quality of the learning experience (stress level, motivation to restart, self‐evaluation of the preparation, and difficulty) was quantified using a visual analog scale. Duration of the procedure was also measured in both groups. 3D measurements for each tooth were performed using an STL comparison software. Results: There were no significant differences between groups in terms of stress and self‐evaluation of the preparation. Students in the guided bur group reported significantly lower perception of exercise difficulty (p <.001) and significantly higher motivation to restart the procedure (p <.001). The guided bur group performed the procedure in 16.4% less time than the rounded bur group. The use of the guided bur led to a 23% over‐reduction, whereas the use of the rounded bur led to a 10% under‐reduction. Conclusions: Overall, the present study shows that the guided bur provides significant improvement in the student's learning experience with increased motivation and decreased perception of difficulty. It shortens the duration of procedure performance, but it also induces a reduction in preparation accuracy. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the performance of ceramic, hybrid ceramic, and commercial plastic bloc root canal simulator (RCS) as preclinical training aids in the learning phase of endodontic treatments. A previously developed hydroxyapatite ceramic RCS was improved by adding epoxy resin to the ceramic matrix to more closely mimic the organic phase of dentin and to simulate the clinical situation as realistically as possible. The sintered hydroxyapatite ceramic RCS was vacuum infiltrated with epoxy resin, and the degree of infiltration was evaluated by methylene blue staining. The suitability of the resin-infiltrated ceramic simulator (CR) for preclinical endodontic training was compared to that of a non-infiltrated ceramic simulator (C) and a commercial epoxy bloc (P) using a cohort of 30 dental students at one dental school in France. The study was conducted in 2016. The students' perceptions following the required exercises using the CR, C, and P were scored using a questionnaire. The learning outcomes were also assessed by examining the canal preparations that the students performed on extracted teeth using a master cone try-in test. The vacuum process resulted in a good degree of resin infiltration into the ceramic. The questionnaire showed that the C and CR groups generally reported greater satisfaction, especially for radiographic visualizations, than the P group. The CR group had a higher score than the P group for tactile sensation. There was no significant difference among the three groups with respect to the canal preparations using extracted teeth. Resin infiltration improved the performance of the ceramic RCS, especially with respect to perception during root canal instrumentation. A larger scale student training investigation and an assessment by experienced endodontists are required to validate the model. [ABSTRACT FROM AUTHOR]

Purpose: To compare the effect of different treatments (heat capsule, ultrasound, and dual treatments) on the setting kinetics and maturation properties of a conventional GIC (EQUIA, GC) to that of standard setting. Methods: The optimal durations of the heat and ultrasonic treatments were determined by monitoring changes in the COO-/COOH ratio, surface hardness, and temperature within the samples. The influence of optimal treatments on the maturation properties of the GIC (microhardness, and 3-point flexural strength) were assessed using GIC samples incubated in artificial saliva for 24 hours, 1 month, and 3 months. Results: The optimal durations of the heat and ultrasonic treatments for accelerating setting were 5 minutes and 35 seconds, respectively. The dual treatment using the optimal conditions of the individual treatments further enhanced the setting kinetics. A temperature peak (49°C) within the GIC was detected during setting. Only the dual treatment increased the mechanical properties of the GIC after 24 hours compared to the control, while no significant difference was observed after 1 and 3 months. [ABSTRACT FROM AUTHOR]

The treatment of infants with trisomy 21 (TS21) with a myostimulation plate can improve their development and quality of life. The manufacture of these plates requires an accurate cast of the maxilla, and their efficacy relies on their stability and retention. As such, the quality of the impression is a determining factor. The lack of commercially available stock trays for infants with TS21 creates difficulties, including inadequate impression quality and the risk of inhaling impression material. The present technique simplifies impression making for infants with TS21 from 3 months of age to when their maxillary deciduous teeth erupt by using computer-aided design and computer-aided manufacturing (CAD-CAM) impression trays. Sixty-five stored gypsum maxillary casts from infants with TS21 that had been used to manufacture myostimulation plates were analyzed to select four differently sized representative casts for designing the impression trays. A CAD software program was used to digitally shape four sizes of the impression tray from the selected gypsum casts. Practitioners interested in this approach can download and export the standard tessellation language (STL) files using a quick response (QR) code. The impression trays should be manufactured with the stereolithography additive technique using biocompatible resin. This technique allows practitioners to make accurate maxilla impressions for infants with TS21 by manufacturing their own impression trays using the free-access STL files rather than the cumbersome conventional method., (Copyright © 2023 Editorial Council for The Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Objective: The aim of this study was to evaluate the influence of root canal curvature (curved and straight root canals), prepared using reciprocating and rotary files, on wall cleanliness during root canal treatments., Methods: Thirty curved and 30 straight human root canals were prepared using ProTaper (Dentsply), Pro- Taper Next (Dentsply) and Reciproc files (Dentsply) (n=20/group). The roots were split longitudinally and observed using a scanning electron microscope. Six micrographs were obtained at 1, 3 and 5 mm from the working length (WL). Two blinded observers scored the amount of debris. Mean debris scores were compared using a non-parametric the Mann-Whitney U test or Kruskal-Wallis test, and a Bonferroni correction was used for multiple comparisons., Results: Considering all the shaping systems together, the debris scores were lower in curved root canals (P<0.05). Reciproc and ProTaper Next performed better than ProTaper in straight canals (P<0.05). No difference was found between ProTaper Next and Reciproc regardless of the canal curvature or distance from the WL. Considering all the shaping systems together, cleanliness increased when pulling away from the WL., Conclusion: The anatomical configuration of the root canal influences the quality of cleaning by shaping instruments regardless of the instrument kinematics during endodontic procedures. In every circumstance, the last millimetres of the apical third remain the most difficult area to clean., Competing Interests: Conflict of Interest: No conflict of interest was declared by the authors., (Copyright: © 2020 European Endodontic Journal.)