Effectiveness of a New Broadrick Flag Support for Assisting Students With the Design of an Occlusal Plane.

OBJECTIVE: 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. MÉTHODOLOGY: 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. RÉSULTS: 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. CONCLUSION: 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.

Improving the Mechanical Properties of Hot Rolled Low-Carbon Copper-Containing Steel by Adjusting Quenching Roll Speed.

This paper presents a comprehensive study of the impact of quenching roll speed on enhancing the low-temperature toughness of a low-carbon copper-containing steel. The microstructure characteristics, such as the prior austenite grains, and the distribution and volume fraction of precipitates, are observed using optical microscopy, scanning electron microscopy, transmission electron microscopy, and small-angle scattering X-ray. The results show that a decrease in the quenching roller speed (2 m/min) contributes to the achievement of more excellent low-temperature toughness (the average value is 232 J), although the prior austenite grains exhibit a relatively larger size in this case. The tempering treatment results in the precipitation of a large amount of 9R-type Cu-rich particles, regardless of the quenching roller speed. Reducing the quenching roller speed contributes to the increase in the volume fraction of Cu-rich particles, which is considered to be the main factor contributing to the achievement of excellent low-temperature toughness.

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OBJECTIVES: To assess the effectiveness and safety of prone positioning in the treatment of neonatal respiratory distress syndrome (NRDS) using invasive respiratory support. METHODS: A prospective study was conducted from June 2020 to September 2023 at Suining County People's Hospital, involving 77 preterm infants with gestational ages less than 35 weeks requiring invasive respiratory support for NRDS. The infants were randomly divided into a supine group (37 infants) and a prone group (40 infants). Infants in the prone group were ventilated in the prone position for 6 hours followed by 2 hours in the supine position, continuing in this cycle until weaning from the ventilator. The effectiveness and safety of the two approaches were compared. RESULTS: At 6 hours after enrollment, the prone group showed lower arterial blood carbon dioxide levels, inspired oxygen concentration, oxygenation index, rates of tracheal intubation bacterial colonization, and Neonatal Pain, Agitation and Sedation Scale scores compared to the supine group (P<0.05). There were no significant differences between the groups in terms of pH, arterial oxygen pressure, positive end-expiratory pressure, duration of mechanical ventilation, accidental extubation, ventilator-associated pneumonia, air leak syndrome, skin pressure sores, feeding intolerance, and grades II-IV intraventricular hemorrhage (P>0.05). CONCLUSIONS: Compared to supine positioning, prone ventilation effectively improves oxygenation, increases comfort, and reduces tracheal intubation bacterial colonization in neonates requiring mechanical ventilation for NRDS, without significantly increasing adverse reactions.

Effect of Reheating Temperature on the Microstructure and Properties of Cu-Containing 440 MPa Grade Non-Tempered Ship Plate Steel.

This study investigated the effects of reheating temperature on the microstructure and mechanical properties of Cu-containing 440 MPa grade non-tempered ship plate steel. The mechanical properties test, thermodynamic simulation, optical microscopy, scanning electron microscopy, transmission electron microscopy, and other tests were performed. The results revealed that with increasing reheating temperature, the ferrite grain size of Cu-containing 440 MPa non-tempered ship plate steel increased. Also, with increasing reheating temperature, the size of copper particles and niobium-titanium composite precipitates in the original austenite decreased. Consequently, this led to a weakening of the pinning effect on the original austenite and an increase in the size of the transformed ferrite grains. Moreover, with increasing reheating temperature, the number of Cu precipitates in the test steel after air cooling and rolling increased, while the size of the precipitates decreased, thereby weakening the solid solution strengthening effect of Cu, and precipitation was enhanced. Additionally, as the reheating temperature increased, the tensile strength and yield strength of the air-cooled test steel after rolling increased, while the impact toughness decreased.

Engineering Precise Interconnected Porosity in ß-Tricalcium Phosphate (ß-TCP) Matrices by Means of Top-Down Digital Light Processing.

This study evaluated the biocompatibility and accuracy of 3D-printed ß-tricalcium phosphate (ß-TCP) pure ceramic scaffolds. A specific shaping process associating a digital light processing (DLP) 3D printer and a heat treatment was developed to produce pure ß-TCP scaffolds leaving no polymer binder residue. The ß-TCP was characterised using X-ray diffraction, infrared spectroscopy and the detection of pollutants. The open porosity of produced matrices and their resorption were studied by hydrostatic weighing and calcium release measures. The biocompatibility of the printed matrices was evaluated by mean of osteoblast cultures. Finally, macroporous cubic matrices were produced. They were scanned using a micro-Computed Tomography scanner (micro-CT scan) and compared to their numeric models. The results demonstrated that DLP 3D printing with heat treatment produces pure ß-TCP matrices with enhanced biocompatibility. They also demonstrated the printing accuracy of our technique, associating top-down DLP with the sintering of green parts. Thus, this production process is promising and will enable us to explore complex phosphocalcic matrices with a special focus on the development of a functional vascular network.

The Effect of Direct Quenching on the Microstructure and Mechanical Properties of NiCrMo and Cu-Bearing High-Strength Steels.

In this work, two types of 590 MPa grade steels, composed of NiCrMo steel and Cu-bearing steel, were processed using traditional offline quenching and tempering and direct quenching (DQ) and tempering. The influence of DQ on microstructural evolution and strengthening mechanisms of these two types of steel was investigated. Grain refinement and dislocation density increase were determined by controlled rolling and following the DQ process in both two types of steel. In Cu-bearing steels, the refined grains and high-density dislocation further promoted the precipitation behavior of Cu-rich particles and alloyed carbides during the tempering treatment. Compared with traditionally quenched and tempered steels, NiCrMo steels after the direct quenching and tempering (DQT) process achieved 106 MPa higher yield strength through grain refinement strengthening and dislocation strengthening, while the Cu-bearing steels after the DQT process achieved 159 MPa higher yield strength through grain refinement strengthening, dislocation strengthening, and precipitation strengthening. The contribution degree of different strengthening mechanisms was quantitatively analyzed. Grain refinement also compensated for the toughness loss caused by the increase in dislocation, leading to an impact energy of 237 J and 248 J at -84 °C for NiCrMo and Cu-bearing steels after DQT, respectively.

Effect of Manganese on the Strength-Toughness Relationship of Low-Carbon Copper and Nickel-Containing Hull Steel.

The influence of varying the manganese (Mn) contents of high-strength copper-containing hull steel on its microstructural evolution and mechanical properties was investigated. With increasing Mn content from 2 to 5%, the tensile strength of the steel increased by ~100 MPa, while the elongation of steel remained at ~23.5%, indicating good plasticity. However, the 2Mn sample had 128 J higher low-temperature (-84 °C) impact work than the 5Mn sample. The microstructures of different Mn steels were composed of fresh martensite (FM), ferrite/tempered martensite (F/TM), and reversed austenite (RA). The increase in Mn content markedly increased the presence of RA and intensified the work hardening caused by the transformation-induced plasticity (TRIP) effect during the tensile process. However, as the phase transformation in different Mn steels occurred in the early stage of strain and did not extend throughout the entire plastic deformation process, increasing plasticity via phase transformation was difficult. In addition, although the volume fraction of RA increased significantly in 4Mn and 5Mn steels, the stability of RA significantly decreased. The presence of numerous metastable blocks and coarse lath-like RA contributed little to low-temperature impact work and was even detrimental to toughness. The substantial fresh martensite resulting from phase transformation facilitated microcrack generation, owing to rapid volume expansion and mutual impacts, thus reducing the work required for crack formation. Additionally, the abundance of deformation twins significantly reduced the work needed for crack propagation. These combined actions significantly reduced the low-temperature toughness of 4Mn and 5Mn steels.

Systematic literature review of in vivo rat femoral defect models using biomaterials to improve the induced membrane technique: a comprehensive analysis.

Purpose: The aim of this study was to conduct a systematic literature review analyzing the results of in vivo rat femoral defect models using biomaterials for improving the induced membrane technique (IMT). Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, the PubMed, Embase, and Web of Science databases were searched. Inclusion criteria were studies reporting results of the IMT in in vivo rat femoral critical-sized defect models using a biomaterial possibly combined with molecules. Methodologic quality was assessed with the Animal Research: Reporting In Vivo Experiments guidelines. Results: Twenty studies met the inclusion criteria. Femoral stabilization with plate and screws was the most frequent. Histologic, biomechanical, and/or radiologic analyses were performed. In two-stage strategies, the PMMA spacer could be associated with bioactive molecules to enhance IM growth factor expression and improve bone formation. Modulating the roughness of spacers could increase IM thickness and accelerate its formation. In one-stage strategies, human tissue-derived membranes combined with bone grafting achieved bone formation comparable to a standard IMT. All calcium phosphate grafts seemed to require a functionalization with growth factors or bone marrow mononuclear cells to improve outcomes compared with non-functionalized grafts. Conclusion: This systematic review described the main parameters of the in vivo rat femoral defect models using biomaterials to improve the induced membrane technique. Although the studies included had several methodological limitations that may limit the scope of these conclusions, one- and two-stage strategies reported promising results with biomaterials to improve the IMT.

First-in-Human Study of the Reversible BTK Inhibitor Nemtabrutinib in Patients with Relapsed/Refractory Chronic Lymphocytic Leukemia and B-Cell Non-Hodgkin Lymphoma.

Nemtabrutinib is an orally bioavailable, reversible inhibitor of Bruton tyrosine kinase (BTK) and C481S mutant BTK. We evaluated the safety, pharmacology, and antitumor activity of nemtabrutinib in relapsed/refractory hematologic malignancies. Forty-eight patients with chronic lymphocytic leukemia (CLL), B-cell non-Hodgkin lymphoma (NHL), or Waldenström macroglobulinemia (WM), relapsed/refractory after ≥2 prior therapies were enrolled in the open-label, single-arm, phase I MK-1026-001 study (NCT03162536) to receive nemtabrutinib 5 to 75 mg once daily in 28-day cycles. Dose finding progressed using a 3 + 3 dose escalation design. Primary endpoints were safety and the recommended phase II dose (RP2D). Among 47 treated patients, 29 had CLL, 17 had NHL, and 1 had WM. Grade ≥3 treatment-emergent adverse events occurred in 37 (89%), most commonly neutropenia (11; 23.4%), febrile neutropenia (7; 14.9%), and pneumonia (7; 14.9%). The RP2D was 65 mg daily. An overall response rate of 75% was observed in patients with CLL at 65 mg daily. SIGNIFICANCE: This first-in-human phase I study demonstrates the safety and preliminary efficacy of nemtabrutinib in patients with relapsed/refractory B-cell malignancies. These data support further exploration of nemtabrutinib in larger clinical studies. This article is featured in Selected Articles from This Issue, p. 5.

Parameter Optimization of Model Predictive Direct Motion Control for Distributed Drive Electric Vehicles Considering Efficiency and the Driving Feeling.

This paper presents a novel motion control strategy based on model predictive control (MPC) for distributed drive electric vehicles (DDEVs), aiming to simultaneously control the longitudinal and lateral motion while considering efficiency and the driving feeling. Initially, we analyze the vehicle's dynamic model, considering the vehicle body and in-wheel motors, to establish the foundation for model predictive control. Subsequently, we propose a model predictive direct motion control (MPDMC) approach that utilizes a single CPU to directly follow the driver's commands by generating voltage references with a minimum cost function. The cost function of MPDMC is constructed, incorporating factors such as the longitudinal velocity, yaw rate, lateral displacement, and efficiency. We extensively analyze the weighting parameters of the cost function and introduce an optimization algorithm based on particle swarm optimization (PSO). This algorithm takes into account the aforementioned factors as well as the driving feeling, which is evaluated using a trained long short-term memory (LSTM) neural network. The LSTM network labels the response under different weighting parameters in various working conditions, i.e., "Nor", "Eco", and "Spt". Finally, we evaluate the performance of the optimized MPDMC through simulations conducted using MATLAB and CarSim software. Four typical scenarios are considered, and the results demonstrate that the optimized MPDMC outperforms the baseline methods, achieving the best performance.

Development of impression trays for treating infants with trisomy 21 before their deciduous teeth erupt.

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.

Shaping Ability of F6 SkyTaper®, Hyflex® EDM One File, and One Curve®: A Micro-computed Tomographic Evaluation in Curved Root Canals.

OBJECTIVE: The present study aimed to compare the shaping ability of the F6 SkyTaper® (F6S), HyFlex® EDM OneFile (HEDM), and One Curve® (OC) nickel-titanium single-file instruments using micro-computed tomography. METHODS: Fifty-two mesiobuccal roots of maxillary first molars, with a degree of curvature between 20° and 42°, were randomised into three experimental groups (n=15 per group): F6S, HEDM, and OC, and a non-instrumented control group (n=7). All specimens were scanned by micro-computed tomography before and after instrumentation. The following parameters were evaluated: preparation time, volume of dentine removed, cutting efficiency, unshaped surfaces, and canal transportation. Cutting efficiency was analysed using an ANOVA parametric test and Tukey's multiple comparison post hoc test. Other parameters were analysed using a non-parametric Kruskall-Wallis test followed by Dunn's multiple comparison post hoc test. RESULTS: No instrument separation occurred during instrumentation. No significant differences were found between the instrument groups with respect to all the parameters (p>0.05). All the instruments induced morphological changes in the root canal dentine (p<0.05) and tended to increase canal transportation toward the coronal portion of the root canals (p>0.05). CONCLUSION: All instruments were able to shape curved canals and preserve their original anatomy. Single-file endodontic procedures with these instruments can be used with comparable changes in the root canal shape with minimal transportation. (EEJ-2022-01-06).

In Vitro and In Vivo Evaluation of a Bio-Inspired Adhesive for Bone Fixation.

Compared to metallic hardware, an effective bone adhesive can revolutionize the treatment of clinically challenging situations such as comminuted, articular, and pediatric fractures. The present study aims to develop such a bio-inspired bone adhesive, based upon a modified mineral-organic adhesive with tetracalcium phosphate (TTCP) and phosphoserine (OPS) by incorporating nanoparticles of polydopamine (nPDA). The optimal formulation, which was screened using in vitro instrumental tensile adhesion tests, was found to be 50%molTTCP/50%molOPS-2%wtnPDA with a liquid-to-powder ratio of 0.21 mL/g. This adhesive has a substantially stronger adhesive strength (1.0-1.6 MPa) to bovine cortical bone than the adhesive without nPDA (0.5-0.6 MPa). To simulate a clinical scenario of autograft fixation under low mechanical load, we presented the first in vivo model: a rat fibula glued to the tibia, on which the TTCP/OPS-nPDA adhesive (n = 7) was shown to be effective in stabilizing the graft without displacement (a clinical success rate of 86% and 71% at 5 and 12 weeks, respectively) compared to a sham control (0%). Significant coverage of newly formed bone was particularly observed on the surface of the adhesive, thanks to the osteoinductive property of nPDA. To conclude, the TTCP/OPS-nPDA adhesive fulfilled many clinical requirements for the bone fixation, and potentially could be functionalized via nPDA to offer more biological activities, e.g., anti-infection after antibiotic loading.

Efficacy of Intra-Articular Injection of Botulinum Toxin Type A (IncobotulinumtoxinA) in Temporomandibular Joint Osteoarthritis: A Three-Arm Controlled Trial in Rats.

Temporomandibular disorders (TMD) are complex pathologies responsible for chronic orofacial pain. Intramuscular injection of botulinum toxin A (BoNT/A) has shown effectiveness in knee and shoulder osteoarthritis, as well as in some TMDs such as masticatory myofascial pain, but its use remains controversial. This study aimed to evaluate the effect of intra-articular BoNT/A injection in an animal model of temporomandibular joint osteoarthritis. A rat model of temporomandibular osteoarthritis was used to compare the effects of intra-articular injection of BoNT/A, placebo (saline), and hyaluronic acid (HA). Efficacy was compared by pain assessment (head withdrawal test), histological analysis, and imaging performed in each group at different time points until day 30. Compared with the rats receiving placebo, those receiving intra-articular BoNT/A and HA had a significant decrease in pain at day 14. The analgesic effect of BoNT/A was evident as early as day 7, and lasted until day 21. Histological and radiographic analyses showed decrease in joint inflammation in the BoNT/A and HA groups. The osteoarthritis histological score at day 30 was significantly lower in the BoNT/A group than in the other two groups (p = 0.016). Intra-articular injection of BoNT/A appeared to reduce pain and inflammation in experimentally induced temporomandibular osteoarthritis in rats.

Injectable Chitosan-Based Hydrogels for Trans-Cinnamaldehyde Delivery in the Treatment of Diabetic Foot Ulcer Infections.

Diabetic foot ulcers (DFU) are among the most common complications in diabetic patients and affect 6.8% of people worldwide. Challenges in the management of this disease are decreased blood diffusion, sclerotic tissues, infection, and antibiotic resistance. Hydrogels are now being used as a new treatment option since they can be used for drug delivery and to improve wound healing. This project aims to combine the properties of hydrogels based on chitosan (CHT) and the polymer of ß cyclodextrin (PCD) for local delivery of cinnamaldehyde (CN) in diabetic foot ulcers. This work consisted of the development and characterisation of the hydrogel, the evaluation of the CN release kinetics and cell viability (on a MC3T3 pre-osteoblast cell line), and the evaluation of the antimicrobial and antibiofilm activity (S. aureus and P. aeruginosa). The results demonstrated the successful development of a cytocompatible (ISO 10993-5) injectable hydrogel with antibacterial (99.99% bacterial reduction) and antibiofilm activity. Furthermore, a partial active molecule release and an increase in hydrogel elasticity were observed in the presence of CN. This leads us to hypothesise that a reaction between CHT and CN (a Schiff base) can occur and that CN could act as a physical crosslinker, thus improving the viscoelastic properties of the hydrogel and limiting CN release.

Effect of Microstructural Evolution on the Mechanical Properties of Ni-Cr-Mo Ultra-Heavy Steel Plate.

In this study, microstructural evolution and its effects on mechanical properties across the thickness of a 120 mm Ni-Cr-Mo industrial ultra-heavy steel plate were quantitatively investigated by means of optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM) and electron back-scatter diffraction (EBSD). The results show that the martensite fraction is 65% at 10 mm and disappears at 40 mm, while granular bainite appears at 35 mm and climbs up to as high as 32% at 60 mm, with M-A constituents significantly coarsened. The strength drops with the gradual coarsening of the laths as well as decreased martensite fraction from the surface to the centre. The toughness is mainly affected by the block size and the morphology and quantity of M-A constituents. This study established a multivariate function between the microstructure and toughness (50% fibre area transition temperature, FATT50) with careful consideration of the influence of effective grain size (EGS) and M-A constituent size distribution.

Evaluation of a Medical Grade Thermoplastic Polyurethane for the Manufacture of an Implantable Medical Device: The Impact of FDM 3D-Printing and Gamma Sterilization.

Three-dimensional printing (3DP) of thermoplastic polyurethane (TPU) is gaining interest in the medical industry thanks to the combination of tunable properties that TPU exhibits and the possibilities that 3DP processes offer concerning precision, time, and cost of fabrication. We investigated the implementation of a medical grade TPU by fused deposition modelling (FDM) for the manufacturing of an implantable medical device from the raw pellets to the gamma (γ) sterilized 3DP constructs. To the authors' knowledge, there is no such guide/study implicating TPU, FDM 3D-printing and gamma sterilization. Thermal properties analyzed by differential scanning calorimetry (DSC) and molecular weights measured by size exclusion chromatography (SEC) were used as monitoring indicators through the fabrication process. After gamma sterilization, surface chemistry was assessed by water contact angle (WCA) measurement and infrared spectroscopy (ATR-FTIR). Mechanical properties were investigated by tensile testing. Biocompatibility was assessed by means of cytotoxicity (ISO 10993-5) and hemocompatibility assays (ISO 10993-4). Results showed that TPU underwent degradation through the fabrication process as both the number-averaged (Mn) and weight-averaged (Mw) molecular weights decreased (7% Mn loss, 30% Mw loss, p < 0.05). After gamma sterilization, Mw increased by 8% (p < 0.05) indicating that crosslinking may have occurred. However, tensile properties were not impacted by irradiation. Cytotoxicity (ISO 10993-5) and hemocompatibility (ISO 10993-4) assessments after sterilization showed vitality of cells (132% ± 3%, p < 0.05) and no red blood cell lysis. We concluded that gamma sterilization does not highly impact TPU regarding our application. Our study demonstrates the processability of TPU by FDM followed by gamma sterilization and can be used as a guide for the preliminary evaluation of a polymeric raw material in the manufacturing of a blood contacting implantable medical device.

Comparison of chemical-induced temporomandibular osteoarthritis rat models (monosodium iodoacetate versus collagenase type II) for the study of prolonged drug delivery systems.

OBJECTIVE: To compare two agents that can induce a rat model of temporomandibular joint osteoarthritis (TMJOA) by chemical induction: monosodium iodoacetate (MIA) and collagenase type 2 (Col-2). We wished to ascertain the best agent for assessing drug-delivery systems (DDSs). METHOD: Male Wistar rats underwent intra-articular injection with MIA or Col-2. They were manipulated for 30 days. The head withdrawal threshold (HWT), immunohistological assessment, and positron emission tomography (PET) were used to evaluate the relevance of our models. RESULTS: For both the MIA and Col-2 groups, pain persisted for 30 days after injection. Change in the HWT showed that Col-2 elicited a strong action initially that decreased progressively. MIA had a constant action upon pain behavior. Histology of TMJ tissue from both groups showed progressive degradation of TMJ components. CONCLUSIONS: MIA and Col-2 induced orofacial pain by their local chemical action on TMJs. However, based on a prolonged and greater sustained effect on the pain threshold, persistent histological changes, and imaging results, MIA appeared to be more suitable for creation of a rat model of TMJOA for the study of DDSs.

Impact of type of bonding agent on adhesion of CAD-CAM denture bases and teeth manufactured using different techniques: A preliminary study.

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, ײ= 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, ײ= 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. CLINICAL SIGNIFICANCE: The present study suggests that the uncured liquid resin (Denture Base) used as a bonding agent and the denture base and tooth materials (V-Print and CediTEC DT) manufactured by SLA and the subtractive technique are clinically compatible.

Sodium carbonate improves adherence of two-layer alginate for preliminary impressions of complete dentures.

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 Na2CO3. 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 (α= 0.05). RESULTS: The bond strength (0.034 ±0.005 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 (ײ= 16; P< 0.0001). CLINICAL SIGNIFICANCE: Conditioning the surface of the first layer of irreversible hydrocolloid with 0.7% sodium carbonate improved adhesion between the two layers and may help clinicians improve the quality of the preliminary impressions of removable complete dentures.