Touch-cure activation by marketed universal resin luting cements of their associated primer to dentin.

PURPOSE: The aim of this study was to investigate the dentin shear bond strength (SBS) and bonding interface of three recently developed "universal" resin luting cements based on different modalities. METHODS: The dentin SBS and interfacial analysis of three recently launched "universal" resin luting cements, namely, G-Cem One, RelyX Universal and Panavia SA cement universal, were studied. All bonding protocols, including the previous use of their dedicated primer or universal adhesive in touch-cure mode or light-cure mode were performed. Variolink Esthetic LC used in conjunction with Scotchbond Universal Plus was used as a control group. For each group (n = 9), 10 specimens were tested for dentin SBS and two were examined by scanning electron microscopy. SBS were analyzed by two-way ANOVA followed by Dunnett's test. RESULTS: SBS values showed that the three "universal" resin luting cements tested exhibit different adhesive behaviors. G-Cem One with its touch-cure activated primer had a greater SBS to dentin (25.5 MPa) than that of the control group (22.1 MPa). CONCLUSION: "Universal" resin luting cements have variable efficacy when used in self-curing mode. The touch-curing mode is also of concern but may show high potential for some formulations.

Perceptions regarding the use of a three-dimensionally-printed manufactured educational simulator for periodontal treatment of intraosseous and interradicular lesions.

PURPOSE/OBJECTIVES: Treating intraosseous lesions (IOLs) and interradicular bone lesions (IRLs) is an extremely technical dental procedure in periodontics. Instrumentation of these lesions is often perceived as difficult by students and inexperienced dentists before they perform a certain number of procedures on patients in the clinic. The aim of this article is to evaluate a cost-effective three-dimensional (3D)-printed educational simulator for the periodontal treatment of IOLs/IRLs (including scaling, incisions and sutures). METHODS: The simulators were first developed digitally, and then manufactured using printable resins and specific materials; finally, they were assembled using different bonding systems. To evaluate the simulators, assessments were gathered from two target populations: undergraduate students and periodontics experts. These individuals tested the simulator and completed a cross-sectional questionnaire based on a Likert scale with comparative and pedagogical items scored from one to five. The purpose of the questionnaire was to compare our simulator to clinical reality (i.e., operation on human jaws) and to an animal simulator (i.e., simulation of porcine jaws). The results are expressed as the mean and standard deviation and were statistically analyzed with the Wilcoxon signed-rank test. RESULTS: Overall, the results were satisfactory for both groups of testers (4.70 and 4.61 out of five for students and experts, respectively, for global satisfaction). CONCLUSIONS: The overall educational relevance of the simulator designed herein highlights the fact that 3D-printed educational simulators could enable efficient cognitive-functional learning for clinical IOL/IRL treatment.

Creation and evaluation of an educational escape room for preclinical training on 3D printing in dentistry.

INTRODUCTION: The benefit of pedagogical escape rooms for dental students' stimulation, interest and knowledge strengthening has been suggested by several studies. However, in previous studies, only a few students were evaluated. This study aims to confirm the purpose of this innovative pedagogical tool in terms of learning consolidation and team building from students' perceptions. We directly incorporated an educational escape game into the fundamental academic formation as a practical-work course for fifth-year dental students. MATERIALS AND METHODS: The present escape game focused on 3D printing, whose implementation fit the different steps of an escape game well. This study was conducted in March 2022. All fifth-year dental students (n = 212) were divided into 5-6 student groups to match the conditions of an escape game. Before entering the room, each student had to complete a cross-sectional knowledge true/false test of 8 questions to assess their general level. Additionally, an 18-question appreciation survey was completed when leaving the room. RESULTS: The students perceived the 3D-printing escape game to be relevant and especially expressed the benefit of being part of a team to exchange and build knowledge. These results suggest knowledge strengthening. The instructional benefit of this process seemed to exceed its mere fun and appealing aspect. CONCLUSION: Our results with a large number of students showed that, from the students' perception, the educational escape game significantly improved knowledge and team-building. It created a supportive learning environment and increased students' motivation. It can provide a fun and effective way to diversify instruction.

Vat Photopolymerization 3D Printing in Dentistry: A Comprehensive Review of Actual Popular Technologies.

In this comprehensive review, the current state of the art and recent advances in 3D printing in dentistry are explored. This article provides an overview of the fundamental principles of 3D printing with a focus on vat photopolymerization (VP), the most commonly used technological principle in dental practice, which includes SLA, DLP, and LCD (or mSLA) technologies. The advantages, disadvantages, and shortcomings of these technologies are also discussed. This article delves into the key stages of the dental 3D printing process, from computer-aided design (CAD) to postprocessing, emphasizing the importance of postrinsing and postcuring to ensure the biocompatibility of custom-made medical devices. Legal considerations and regulatory obligations related to the production of custom medical devices through 3D printing are also addressed. This article serves as a valuable resource for dental practitioners, researchers, and health care professionals interested in applying this innovative technology in clinical practice.

Degree of conversion of 3D printing resins used for splints and orthodontic appliances under different postpolymerization conditions.

OBJECTIVES: To measure the degree of conversion (DC) of different 3D printing resins used for splints or orthodontic appliances under different postpolymerization conditions. MATERIALS AND METHODS: Five 3D-printed photopolymer resins were studied. Each resin was analyzed in liquid form (n = 15), and then cylindrical specimens (n = 135) were additively manufactured and postcured with Form Cure (Formlabs) at different times (10, 60, and 90 min) and temperatures (20 °C, 60 °C, and 80 °C). The DC of each specimen was measured with Fourier transform infrared spectroscopy (FTIR). The data were statistically analyzed using a 3-way ANOVA followed by Tukey's post hoc test. RESULTS: The time and temperature of postpolymerization significantly influenced the DC of each resin: when time and/or temperature increased, the DC increased. For all resins tested, the lowest DC was obtained with a postcuring protocol at 10 min and 20 °C, and the highest DC was obtained at 90 min and 80 °C. However, at 80 °C, the samples showed a yellowish color. CONCLUSIONS: With the Form Cure device, the time and temperature of postcuring could have an impact on the DC of the 3D printing resins studied. The DC of the 3D printing resins could be optimized by adjusting the postpolymerization protocol. CLINICAL RELEVANCE: Regardless of the resin used, when using the Form Cure device, postcuring at 60 min and 60 °C would be the minimal time and temperature conditions for achieving proper polymerization. Beyond that, it would be preferable to increase the postcuring time to boost the DC.

Flexural properties and dentin adhesion in recently developed self-adhesive bulk-fill materials.

PURPOSE: This study investigated the flexural properties, shear bond strength (SBS) and interface to dentin of three recently developed self-adhesive bulk-fill materials. METHODS: Bars of Surefil One (SO), Cention N (CN), Activa BioActive Restorative (AB) and EQUIA Forte HT Fil (EQUIA) were tested for flexural strength and flexural modulus in self-curing and light-curing modes. In addition, SBS to dentin was tested in specimens without pretreatment and after application of universal adhesive (Scotchbond Universal). EQUIA was used as the control material. RESULTS: The flexural properties were significantly better in light-curing mode for all materials except CN. CN had the highest SBS values after universal adhesive application (33.8 MPa), and SO had the highest SBS without pretreatment (20.9 MPa). CONCLUSION: The mechanical and adhesive properties of these new materials varied widely.

3D-printed protected face shields for health care workers in Covid-19 pandemic.

The coronavirus pandemic resulted in a shortage of protective equipment. To meet the request of eye-protecting devices, an interdisciplinary consortium involving practitioners, researchers, engineers and technicians developed and manufactured thousands of inexpensive 3D-printed face shields, inside hospital setting. This action leads to the concept of "concurrent, agile, and rapid engineering".

Shear bond strength and interfacial analysis of high-viscosity glass ionomer cement bonded to dentin with protocols including silver diammine fluoride.

PURPOSE: High-viscosity glass ionomer cements (HV-GICs) are reinforced with ultrafine, highly reactive glass particles, as well as a higher-molecular-weight polyalkenoic acid component. Silver diammine fluoride (SDF) is an agent with promising activity against active caries. The present study aimed to evaluate the shear bond strength (SBS) and interfacial morphology of a new HV-GIC bonded to dentin after treatment with various adhesive protocols including SDF. METHODS: HV-GIC cylinders were bonded to dentin after various surface treatments (6 groups, n = 22): water; polyalkenoic acid; SDF; SDF + potassium iodide (KI); SDF + KI + polyalkenoic acid; SDF + KI + two weeks of storage in water + polyalkenoic acid. For each group, 20 samples were tested for SBS after 48 h, and 2 samples were cut and subjected to environmental scanning electron microscopy (E-SEM) and energy-dispersive X-ray (EDX) analysis. RESULTS: No significant differences in SBS were found between any of the protocols tested. However, E-SEM and EDX images showed different interfaces when SDF was applied. CONCLUSION: SDF has no influence on the adhesion of HV-GIC to sound dentin and could potentially improve the cario-resistance of the dentin/HV-GIC interface.

The safety and efficacy of 'over the counter' bleaching products in the UK.

Introduction EU council directive 2011/84/EU resulted in a demand for over the counter (OTC) bleaching products. The industry has latched onto this renewed demand by developing a range of non-hydrogen peroxide OTC products. Aims To determine whether non-hydrogen peroxide OTC whitening products available in the UK are safe and to determine the lightening effect of those products. Materials and methods A total of 21 extracted teeth (11 incisors and ten premolars) were collected and stored in chloramine-T solution. Five days before the study, all teeth were immersed in 5 ml of a standard green tea solution at room temperature (22±2 °C). Roots were sectioned from the teeth and cleaned using an ultrasonic bath. Teeth were then embedded in epoxy resin and sectioned inciso-gingivally to serve as paired test and control specimens. A positive control of 10% carbamide peroxide was used while saline was used as a negative control. Five OTC products were selected from two major British consumer outlets. Initially, products were applied to the teeth samples for two one-hour cycles, followed by the equivalent of one-week's application, according to the manufacturer's instruction. Samples were stored overnight in saline to minimise any effects of dehydration. Shades of teeth were taken blindly by a single trained clinician in a natural light environment against a grey background before and after application of the products. Vickers microhardness tests and scanning electron microscopy (SEM) analysis were undertaken. Results SEM analysis showed surface morphology alterations to varying degrees, with several samples demonstrating a distinct etching pattern post-exposure to the OTC products. Sample three ('Brilliant 5 minute kit') and sample five ('iWhite instant teeth whitening') produced the most extensive surface alterations. Samples three and five also resulted in a significant reduction (p = 0.008) in Vickers microhardness. Two OTC products resulted in a lightening effect less than the negative control saline, whereas two other OTC products resulted in a lightening effect greater than carbamide peroxide. Conclusion This study suggests that non-hydrogen peroxide OTC products have the potential to damage enamel and lighten teeth. The lightening effect of the OTC products is variable, however, it is most likely to occur in sodium chlorite based products.

Shear bond strength and interface analysis between a resin composite and a recent high-viscous glass ionomer cement bonded with various adhesive systems.

OBJECTIVE: This study investigated the shear bond strength (SBS) and interface between a resin composite and a new high-viscous glass ionomer cement (HV-GIC), a HV-GIC, a resin-modified glass ionomer cement (RM-GIC), a bulk-fill flowable composite, and a regular flowable composite bonded with various adhesive systems. METHODS AND MATERIALS: A resin composite (Filtek Z350) was bonded to a new HV-GIC (EQUIA Forte Fil) using various adhesive systems, including a universal adhesive in self-etch and etch-and-rinse mode (Scotchbond Universal), a two-step etch-and-rinse adhesive (Scotchbond 1-XT), a one-step self-etch adhesive (Optibond All-in-one) tested also after silane application (Monobond Plus), and a coating material (EQUIA Forte Coat). The resin composite was also bonded to a HV-GIC (Fuji IX GP), a RM-GIC (Fuji II LC), a bulk-fill flowable composite (SDR), and a regular flowable composite (Tetric Evo Flow) with the universal adhesive in self-etch mode (Scotchbond Universal). Two-way ANOVA followed by Dunnett's post hoc test was used to investigate the difference in SBS. Failures were analyzed by chi-square test. Bonding interfaces were examined by environmental scanning electron microscopy (E-SEM). RESULTS: SBS to EQUIA Forte Fil was significantly lower with Scotchbond 1-XT than with all other adhesive systems. By using Scotchbond Universal with the self-etch technique, the SBS to EQUIA Forte Fil was significantly higher than the SBS to Fuji IX GP and significantly lower than the SBS to Fuji II LC, SDR, and Tetric Evo Flow. E-SEM images showed an intimate contact at all interfaces examined. CONCLUSION: EQUIA Forte Fil showed satisfactory SBS and interfaces with all adhesives tested. CLINICAL RELEVANCE: Bonding between the resin composite and HV-GIC can be achieved using a universal adhesive in self-etch mode, an easy-to-use adhesive system.

Effects of High-Temperature-Pressure Polymerized Resin-Infiltrated Ceramic Networks on Oral Stem Cells.

OBJECTIVES: The development of CAD-CAM techniques called for new materials suited to this technique and offering a safe and sustainable clinical implementation. The infiltration of resin in a ceramic network under high pressure and high temperature defines a new class of hybrid materials, namely polymer infiltrated ceramics network (PICN), for this purpose which requires to be evaluated biologically. We used oral stem cells (gingival and pulpal) as an in vitro experimental model. METHODS: Four biomaterials were grinded, immersed in a culture medium and deposed on stem cells from dental pulp (DPSC) and gingiva (GSC): Enamic (VITA®), Experimental Hybrid Material (EHM), EHM with initiator (EHMi) and polymerized Z100™ composite material (3M®). After 7 days of incubation; viability, apoptosis, proliferation, cytoskeleton, inflammatory response and morphology were evaluated in vitro. RESULTS: Proliferation was insignificantly delayed by all the tested materials. Significant cytotoxicity was observed in presence of resin based composites (MTT assay), however no detectable apoptosis and some dead cells were detected like in PICN materials. Cell morphology, major cytoskeleton and extracellular matrix components were not altered. An intimate contact appeared between the materials and cells. CLINICAL SIGNIFICANCE: The three new tested biomaterials did not exhibit adverse effects on oral stem cells in our experimental conditions and may be an interesting alternative to ceramics or composite based CAD-CAM blocks.

Aging of monolithic zirconia dental prostheses: Protocol for a 5-year prospective clinical study using ex vivo analyses.

BACKGROUND: Recent introduction of computer-aided design/computer-aided manufacturing (CAD/CAM) monolithic zirconia dental prostheses raises the issue of material low thermal degradation (LTD), a well-known problem with zirconia hip prostheses. This phenomenon could be accentuated by masticatory mechanical stress. Until now zirconia LTD process has only been studied in vitro. This work introduces an original protocol to evaluate LTD process of monolithic zirconia prostheses in the oral environment and to study their general clinical behavior, notably in terms of wear. METHODS/DESIGN: 101 posterior monolithic zirconia tooth elements (molars and premolars) are included in a 5-year prospective clinical trial. On each element, several areas between 1 and 2 mm2 (6 on molars, 4 on premolars) are determined on restoration surface: areas submitted or non-submitted to mastication mechanical stress, glazed or non-glazed. Before prosthesis placement, ex vivo analyses regarding LTD and wear are performed using Raman spectroscopy, SEM imagery and 3D laser profilometry. After placement, restorations are clinically evaluated following criteria of the World Dental Federation (FDI), complemented by the analysis of fracture clinical risk factors. Two independent examiners perform the evaluations. Clinical evaluation and ex vivo analyses are carried out after 6 months and then each year for up to 5 years. DISCUSSION: For clinicians and patients, the results of this trial will justify the use of monolithic zirconia restorations in dental practice. For researchers, the originality of a clinical study including ex vivo analyses of material aging will provide important data regarding zirconia properties.Trial registration: ClinicalTrials.gov Identifier: NCT02150226.

Clinical risk factors related to failures with zirconia-based restorations: an up to 9-year retrospective study.

OBJECTIVES: The first objective of this study was to retrospectively evaluate zirconia-based restorations (ZBR). The second was to correlate failures with clinical parameters and to identify and to analyse chipping failures using fractographic analysis. METHODS: 147 ZBR (tooth- and implant-supported crowns and fixed partial dentures (FPDs)) were evaluated after a mean observation period of 41.5 ± 31.8 months. Accessorily, zirconia implant abutments (n=46) were also observed. The technical (USPHS criteria) and the biological outcomes of the ZBR were evaluated. Occlusal risk factors were examined: occlusal relationships, parafunctional habits, and the presence of occlusal nightguard. SEM fractographic analysis was performed using the intra-oral replica technique. RESULTS: The survival rate of crowns and FPDs was 93.2%, the success rate was 81.63% and the 9-year Kaplan-Meier estimated success rate was 52.66%. The chipping rate was 15% and the framework fracture rate was 2.7%. Most fractographic analyses revealed that veneer fractures originated from occlusal surface roughness. Several parameters were shown to significantly influence veneer fracture: the absence of occlusal nightguard (p=0.0048), the presence of a ceramic restoration as an antagonist (p=0.013), the presence of parafunctional activity (p=0.018), and the presence of implants as support (p=0.026). The implant abutments success rate was 100%. CONCLUSIONS: The results of the present study confirm that chipping is the first cause of ZBR failure. They also underline the importance of clinical parameters in regards to the explanation of this complex problem. This issue should be considered in future prospective clinical studies. CLINICAL SIGNIFICANCE: Practitioners can reduce chipping failures by taking into account several risk parameters, such as the presence of a ceramic restoration as an antagonist, the presence of parafunctional activity and the presence of implants as support. The use of an occlusal nightguard can also decrease failure rate.

Compatibility of five self-etching adhesive systems with two resin luting cements.

PURPOSE: The aim of this study was to evaluate the compatibility between five self-etching bonding systems (SEBSs) and two resin luting cements (RLCs) assessed by use of an in vitro dentin shear bond test. MATERIALS AND METHODS: The selected RLCs were: Variolink II in a dual-cure mode and Multilink in a self-cure mode. The SEBSs combined with the RLCs were: two one-step SEBSs (One Up Bond F and Xeno III) and three two-step SEBSs (Clearfil SE Bond, Unifil Bond, and Xeno III primer coupled with Clearfil SE Bond bonding resin as an experimental combination). One hundred fifty human molars were divided into ten groups of fifteen samples each. The samples were tested in shear after seven days of storage at 100% RH and 37°C. After each test, the failure mode was recorded. RESULTS AND CONCLUSIONS: Significant differences in shear bond strength (SBS) were observed according to both the curing mode of the RLC and the adhesive. The one-step systems Xeno III and One Up Bond F revealed a total incompatibility when bonded with the chemical-curing RLC. Conversely, the two-step SEBSs were compatible with chemical and dual-curing RLC. Failure modes and shear values were in good agreement. A positive correlation was found between the pH of the tested adhesive solutions or resins and the SBS data