Layer Technique Research Articles

Masking Ability of Subtractively and Additively Manufactured Dental Ceramic Restorations: A Systematic Review.

To conduct a systematic review on the masking ability of subtractively and additively manufactured dental ceramics. The study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The electronic search was carried out through MEDLINE, Scopus, and Website of Science databases with a date restriction being from 2001 onwards. Publications in English, invitro studies, and studies regarding the evaluation of the masking ability of crown materials that were subtractively and additively manufactured were included. Out of 619 eligible articles, 13 were included. A thickness of 1.5 mm for lithium disilicate (LD) resulted in a dramatic decrease in ∆Eab/∆E00 across all substrates compared to a 1 mm thickness. Low-translucent LD appeared to have the best masking ability regardless of the shade of the try-in paste. Layering flowable composite over the substrates improved masking ability. Darker substrates were the hardest to mask no matter the type of restorative material, try-in paste used, and layering technique. Bilayered restorative materials proved to be superior to monolithic materials regarding masking ability. Increasing the thickness of subtractively manufactured ceramics materials improves the masking ability. 1.5 mm thickness is found to provide the best masking ability for most ceramic materials. Darker substrates prove to be difficult to mask in comparison to lighter substrates and require either thicker materials and/or more opaque cements. Bilayered crowns are recommended for achieving optimal masking while preserving tooth structure. Despite the increasing demand, there is no study available on 3D-printed (additively manufactured) restoration's masking ability. This review provides a comparison of masking abilities of multiple subtractively manufactured ceramic materials and highlight the lack of current knowledge on additively manufactured crown materials. It also emphasizes the importance of having a universal approach to interpreting and communicating color changes between collaborative dental professionals to ensure the same shade predictions. In addition, when masking darker shades, clinicians should be aware that alternative material choice or clinical and technical procedures are essential.

Odontogenic keratocyst management using guided tissue regeneration: Literature review - Two case reports.

Odontogenic cysts of the jaws are pathologies that require timely recognition and management. The initial diagnosis is based on clinical and radiographic appearance and dental history. A variety of surgical treatments are used for odontogenic keratocyst (OKC) depending on the clinical and radiographic presentation. The aim of this report and literature review is to highlight methods to treat OKC combined with guided tissue regeneration (GTR). Two cases with similar clinical presentations are included. Case 1 was a 60-year-old healthy Caucasian female who presented with jaw expansion around teeth #'s 21 and 22. Initial exam revealed clinical gingival health on an intact periodontium. The patient presented with enlarged gingival tissue between teeth #'s 21 and 22 measuring 9 × 12mm and vital teeth without root displacement radiographically. Case 2 had a similar clinical and radiographic presentation located between teeth #'s 5-6. Case 1 treatment included excisional biopsy with complete enucleation of the cystic lesion. Thereafter, GTR was performed using allograft internally then covered with a xenograft externally, resorbable collagen membrane (RCM), and primary closure. Case 2 was managed with excisional biopsy with lesion enucleation, GTR with allogenic bone graft, enamel matrix derivative and RCM, and primary closure. OKC enucleation combined with GTR using mineralized allograft, enamel matrix derivative, and collagen membrane or a layering technique of allograft internally and xenograft externally covered by a collagen membrane showed proper regeneration with stable periodontium at 6-36 months. Guided tissue regeneration is an acceptable treatment for management of OKC. Complete enucleation of an OKC lesion is important to reduce recurrence. The use of allograft with xenograft or allograft with enamel matrix derivative and RCM can provide proper bone fill after OKC removal. Odontogenic cysts are growths that can form in the jaw or soft tissues around the teeth. If not treated, they can grow larger, damage the bone, and even push teeth out of place. To prevent this, it's important to diagnose and remove them early. The most common way to treat these cysts is through a surgical method called enucleation, where the cyst is carefully removed. In these two cases, enucleation was used along with guided tissue regeneration, a technique to help the bone and tissue heal better after surgery. In the first case, a bone graft (made from human and animal bone) and a special material called a resorbable collagen membrane were used to protect and support the healing area. In the second case, a mineralized bone graft along with a substance that helps repair tissues called an enamel matrix derivative, and the same collagen membrane were used. Both patients healed well, and over the next 6 to 36 months, their bone and tissues around the teeth regenerated properly.

Ensemble deep learning and EfficientNet for accurate diagnosis of diabetic retinopathy

Diabetic Retinopathy (DR) stands as a significant global cause of vision impairment, underscoring the critical importance of early detection in mitigating its impact. Addressing this challenge head-on, this study introduces an innovative deep learning framework tailored for DR diagnosis. The proposed framework utilizes the EfficientNetB0 architecture to classify diabetic retinopathy severity levels from retinal images. By harnessing advanced techniques in computer vision and machine learning, the proposed model aims to deliver precise and dependable DR diagnoses. Continuous testing and experimentation shows to the efficiency of the architecture, showcasing promising outcomes that could help in the transformation of both diagnosing and treatment of DR. This framework takes help from the EfficientNet Machine Learning algorithms and employing advanced CNN layering techniques. The dataset utilized in this study is titled ’Diagnosis of Diabetic Retinopathy’ and is sourced from Kaggle. It consists of 35,108 retinal images, classified into five categories: No Diabetic Retinopathy (DR), Mild DR, Moderate DR, Severe DR, and Proliferative DR. Through rigorous testing, the framework yields impressive results, boasting an average accuracy of 86.53% and a loss rate of 0.5663. A comparison with alternative approaches underscores the effectiveness of EfficientNet in handling classification tasks for diabetic retinopathy, particularly highlighting its high accuracy and generalizability across DR severity levels. These findings highlight the framework’s potential to significantly advance the field of DR diagnosis, given more advanced datasets and more training resources which leads it to be offering clinicians a powerful tool for early intervention and improved patient outcomes.

Effect of Glass Fiber Reinforcement on Marginal Microleakage in Class II Composite Restorations: An In Vitro Pilot Study.

Background: Polymerization shrinkage of composite resins affects the marginal closure of direct dental restorations. It is responsible for developing secondary caries and indirectly affects the survival rate of restorations. This study aims to investigate the null hypothesis, which states that there are no significant differences in the marginal microleakage of Class II restorations when examined in vitro using different dental adhesives, whether the restoration material used is a composite with glass fiber reinforcement or not. Methods: Class II cavities were prepared on both proximal surfaces of thirty-six extracted human molars. A single-component (Universal VivaPen) and a two-component (Futurabond DC) self-etch adhesive system were used for the restorations in the control group (Charisma Classic) and the experimental group (Charisma Classic with Interlig glass fiber strip). An oblique layering technique and a 40-s soft-start light-curing polymerization were used. After selective pre-isolation, the specimens were placed in a 0.2% methylene blue solution and incubated at 37 °C for 24 h. The teeth were sectioned in the mesiodistal direction, and two examiners examined and graded the extent of dye penetration. Statistical analysis was conducted using the Mann-Whitney U and chi-square tests (p < 0.05). Results: All the composite restorations reinforced with glass fiber showed significantly reduced dye infiltration compared to the control group (p < 0.05). A significant difference (p < 0.05) was also observed between the two adhesives. Conclusions: The null hypothesis was rejected. Glass fiber strips significantly reduced composite restoration microleakage regardless of the adhesive. The marginal fit of the restoration was also influenced by the adhesive system used.

REVIEW ON PELLETIZATION: DRY POWDER LAYERING OF PELLETS USING TANGENTIAL SPRAY ROTOR PROCESSOR/INSERT

Pelletization turns fine powders or granules into small, round pellets for easy flow and handling. These pellets offer advantages such as improved absorption, modified drug release patterns &amp; reduced irritation at application sites. Dry powder layering is gaining popularity in the pharmaceutical industry due to its cost and time efficiency. This method is an effective and straightforward process, can be alternative to liquid-based coating techniques. In recent years, active pharmaceutical ingredient layering onto multi-particulate core materials. One innovative pelletization method uses a rotor processor for powder layering. This process involves applying drug powder onto sugar spheres &amp; spraying a binder solution to achieve uniform distribution and enhance drying efficiency. Compared to traditional methods, this dry powder layering is faster &amp; more energy-efficient, reducing drying time &amp; energy consumption. It is a streamlined and eco-friendly method as no solvent is required which makes it beneficial for pellet coating. This article provide insights on the powder layering technique with innovative fluid bed pelletizing technologies like rotor processor, glatt powder coater granulator series, tangential spray in the rotary insert, complex perfect sphere insert and glatt procell series &amp; their applications.

Clinical evaluation of SonicFill bulk resin technique in the restoration of proximal deep caries of primary molars: a two-year randomized controlled trial

Background/purposeTraditional restorative composites require time-consuming incremental layering techniques which poses challenges in pediatric dentistry. SonicFill bulk resin allows for thicker layers to be placed efficiently, reducing treatment time and enhancing filling quality. This prospective, parallel, randomized, controlled clinical study aimed to compare the operative time and outcomes between SonicFill bulk resin and conventional restorative composite for deep proximal restorations in primary molars.Materials and methodsA total of 129 primary molars in patients with proximal deep caries were randomly assigned to two groups. The experimental group (n = 66) received SonicFill bulk resin treatment, while the control group (n = 63) underwent restoration using traditional composite. The operative time was documented, and all teeth were evaluated at 6, 12, 18, and 24 -months post-treatment based on the modified criteria from the United States Public Health Service and radiographic examination score.ResultsThe operative time for SonicFill resin (137.5 ± 5.2 s) revealed a significant reduction compared to traditional composite (193.5 ± 14.4 s), (t = 29.64, P < 0.05). No significant differences were observed between the two groups in terms of colour match, marginal adaptation and so on. Success rates were 95.2% for the control group and 89.4% for the experimental group (χ2 = 1.44, P>0.05).ConclusionThe SonicFill resin technique has proven to be a viable and time-efficient option for the restoration of primary molars with deep proximal caries.Trial registrationThis study was registered in the Chinese Clinical Trial Registry (ChiCTR2200055570) on the date of 13/01/2022.

Microstructural Evolution and Mechanical Property Enhancement in WAAM Components

Abstract Wire arc additive manufacturing (WAAM) is increasingly being recognized as a favourable method for producing large-scale products. The microstructural evolution during the solidification of molten pool in WAAM is influenced by factors such as heat input and the deposited layer sequence. In this study, the impact of different layering sequences on grain growth, microstructure, and mechanical properties was investigated by depositing Inconel 825 alloy using gas metal arc welding. Different layering sequences were employed to minimize the development of columnar grains that typically outcome from oscillating beads and bead upon bead within a single layer. The unidirectional heat flow in conventional layering techniques encourages grain growth in the direction of the heat source, with grains forming at the fusion boundaries and growing upwards. At the interface between previously solidified beads and the liquid metal, nucleation and epitaxial grain growth occur, prominent to the formation of transverse columnar grains, with their size determined by the grain structure of the preceding layer. While traditional stacking sequences tend to produce columnar grains, a zigzag layering approach was found to refine grain growth by disrupting the direction of heat flow and grain development. This resulted in smaller, more fragmented grains, which enhanced the isotropic properties of the material. The study further demonstrated that the anisotropic behavior of wire arc additively manufactured components is closely related to grain growth direction and size, both of which are significantly influenced by the layering sequence. The zigzag layering sequence not only improved hardness and tensile strength compared to conventional layering methods but also enhanced the resolution and linearity of the deposited walls.

Effects of Thin Cell Layer Technique and Nutrient Media Contents of Regeneration and Browning Characteristics of the Laurus nobilis L. Explants

The aim of this study is in order to investigate the effects of explant source, explant type and MS media composition containing different concentrations of sucrose, activated carbon and Coconut milk for regeneration and browning of Laurus nobilis L. using thin cell layer (TCL) culture system. A higher rate of callus (57.15%) and shoot (2%) regeneration and a lower rate of blackening were determined in transversely cut stem TCL explants compared to leaf explants. While 1.33% callus regeneration was achieved in leaf explants; shoot regeneration could not be achieved. While more callus regeneration (35.17%) was found in explants taken from the field, more shoot regeneration (1.5%) and lower rate of browning were obtained in explants taken from in vitro. In the sugar trials, the highest callus regeneration (40.83%) was defined in MS medium containing 30 g/L sucrose supplemented with 1 mg/L BAP, and the highest shoot regeneration (2.5%) was determined in MS medium containing 45 g/L and 60 g/L sucrose supplemented with 1 mg/L BAP. When explant type, explant source and nutrient media composition are considered together; the highest callus regeneration (100%) was obtained in field-sourced stem TCL explants cultured in medium containing 25 mL/L coconut milk and 1 mg/L BAP. The highest shoot regeneration (6.6%) was determined in in vitro stem TCL explants cultured in MS media containing 30, 45, 60 g/L sucrose and 1 mg/L BAP. The lowest percentage of browning (50%) was obtained from in vitro stem TCL explants cultured in MS medium containing 2 g/L activated carbon and 1 mg/L BAP.

An efficient high-quality cutting method for thick SiCf/SiC ceramic matrix composites using UV laser multiline layered scanning with focus increment optimization

Laser-layered scanning techniques have achieved considerable success in cutting and drilling applications. However, their effectiveness in processing SiCf/SiC ceramic matrix composites—critical materials for next-generation aerospace thermal components—remains less than optimal. This study addresses the challenge of enhancing the quality and efficiency of cutting thick samples by being the first to highlight the crucial influence of focus increment adjustments in the laser-layered scanning process. Specifically, it examines the relationship between the predetermined laser focus drop per layer and the actual ablation depth achieved. Systematic analysis explores the impact of focus increment adjustments on both the macroscopic structural alterations during cutting and the microstructural characteristics of the cut surfaces. The findings demonstrate that the UV nanosecond laser multi-line layered scanning technique is particularly effective for processing thick SiCf/SiC samples, achieving a surface area of 5 × 5 mm² (Sa 366.92 nm) in just 117.58 s. By optimising the focus increment, a high and stable material removal rate is maintained throughout the process, reducing surface oxidation, minimising the formation of a recast layer, and reducing fibre interface debonding. Additionally, the study reveals the mechanism behind the formation of surface taper and presents a method to achieve a taper-free surface by adjusting the laser incidence angle. These findings provide valuable insights for the rapid and high-quality machining of matrix composites, offering significant improvements over existing methods.

Engineering plant-based chicken substitutes: Application of fava bean (Vicia Faba) and wheat gluten blend (Triticum Aestivum) via novel layering technique

This study explores feasibility of producing a plant-based chicken analogue using an innovative layering method with sprouted fava bean flour, wheat gluten and beet powder. Analyses of raw and cooked samples were conducted to mimic conventional chicken properties. Results indicate that sprouting process significantly improve protein and amino acid profile of meat analogue from 22 % to 45 % respectively, outperforming conventional chicken. The meat analogue has higher unsaturated fatty acids (UFA) compared to chicken's higher saturated fatty acids (SFA). Prominent enhancements in colour and vitamin B12 enrichment were observed in the meat analogue, underlining the significance of this research. Scanning electron microscopic examination revealed fibrous structures in the meat analogue, with a complex matrix in arrangement. Flavor, texture, and chewiness significantly influenced the organoleptic evaluation, correlating with the texture profile and beany flavor. Ongoing refinements are necessary to address limitations in mimicking chicken and to align with evolving consumer preferences.

Manufacturing Novel Cathodes for Improved Fuel Cell Performance

In Proton Exchange Membrane Fuel Cells (PEMFCs) water generation and management can become a difficult challenge for sustained operation. In short, too much water can flood the electrodes and block the reactant gases, while too little water can induce membrane dehydration and decreased protonic conductivity, highlighting the necessity for optimized hydration of the electrodes. To address this challenge, our efforts are directed toward the refinement of the cathode architecture, to improve the overall mass transport of the reactants and management of product water. The experimental design includes varying the Pt-loading, while optimizing the degree of porosity within the electrode structure. The cathode is fabricated by using an ultrasonic spray-coating method and its loading is determined by X-Ray Fluorescence (XRF). Porosity is managed by the pore size distribution of the additives and unique layering techniques. The performance of these cathodes is isolated by keeping all other materials, components, and parameters identical (e.g., anode loading, membrane, etc.), allowing us to elucidate the performance.

Breeding evaluations in aquaculture using neural networks

Deep learning comes with a portfolio of highly flexible models, known as neural networks (NNs), capable of solving various problems and setting new high standards for prediction accuracy. Nevertheless, whether NNs could be of value in aquaculture selective breeding settings is unclear as the whole topic is underexplored. Furthermore, fine-tuning a plethora of hyperparameters before fitting a neural network is a daunting task. Using simulated and a publicly available dataset on genetic resistance in carp against koi herpes virus (KHV), various neural network architectures were benchmarked against commonly used animal breeding models. More specifically, the simulated datasets comprised 36000 phenotyped animals genotyped for 54000 single nucleotide polymorphisms (SNPs). In contrast, the carp dataset included 1255 carp juveniles with survival recordings for KHV that were genotyped for 15615 SNPs. The assessed NN architectures included multilayer perceptrons (MLPs), convolution neural networks (CNNs) and local convolution neural networks (LCNNs). In addition, the effect of various hyperparameters of neural networks, such as the number of hidden layers, neurons per layer, activation function, learning rate, batch size, and regularisation techniques like dropout, were examined. In the simulated datasets, fully connected models with 5 hidden layers and 100 neurons per layer performed slightly better (1 – 4 %) than ridge-regression best linear unbiased prediction (rrBLUP), while the CNNs gave the lowest prediction accuracies (∼ 14 % lower than MLPs) and the ones from LCNN in between the above (∼ 8 lower than MLPs). Nevertheless, the estimated breeding values from NNs appeared more biased than rrBLUP (mean regression slope of 1.2 for the NN with the highest prediction accuracy vs 1.08). A reverse picture was observed in the case of the carp dataset, where following the application of receiver operating characteristic (ROC) curves, the animal breeding models outperformed neural networks by more than 2 % (based on the area under the curve index). In this case the LCNN had the highest area under the curve index from all NNs. Overall, NNs could be valuable tools in aquaculture breeding programs, though large training datasets of tens of thousands or more of phenotyped and genotyped animals seem to be required.

Explainable deep learning on multi-target time series forecasting: An air pollution use case

Urban air pollution represents a significant threat to public health and the environment, with nitrogen oxides, ozone, and particulate matter being among the most harmful pollutants. These contribute to respiratory and cardiovascular diseases, particularly in urban areas with high traffic and elevated temperatures. Machine learning, especially deep learning, shows promise in enhancing the prediction accuracy of prediction of pollutant's concentrations. However, the “black box” nature of these models often limits their interpretability, which is crucial for informed decision-making. Our study introduces a Temporal Selection Layer technique within deep learning models for time series forecasting to tackle this issue. This technique not only improves prediction accuracy by embedding feature selection directly into the neural network, but also enhances interpretability and reduces computational costs. In particular, we applied this method to hourly concentration data of pollutants, including particulate matter, ozone, and nitrogen oxides, from five urban monitoring sites in Graz, Austria. These concentrations were used as target variables to predict, while identifying the most relevant features and periods that affect prediction accuracy. Comparative analysis with other embedded feature selection methods showed that the Temporal Selection Layer significantly enhances both model effectiveness and transparency. Additionally, we applied explainable techniques to evaluate the impact of weather and time-related factors on air pollution, which also helped assess feature importance. The results show that our approach improves both prediction accuracy and model interpretability, leading finally to more effective pollution management strategies.

The influence of suturing and or gluing of perforated Schneiderian membrane during sinuslift procedure on the outcome: a retrospective study

The sinus lift procedure has become the most common method for maxillary bone augmentation. The most frequently observed intraoperative complication is the perforation of the Schneiderian membrane. Various treatment options have been proposed for managing these perforations, including the use of resorbable membranes, centrifugated blood products as PRF, or PRGF, suturing, and fibrin glue application. While long-term studies exist for the use of resorbable membranes to close perforations, there is limited data on the long-term outcomes of suturing or gluing the perforated sinus membrane. The aim of this retrospective study is to evaluate the long-term outcomes of suturing and/or applying fibrin glue to repair perforated sinus mucosa during sinus floor elevation procedures. Between 2005 and 2009, a total of 692 patients underwent 923 sinus lift surgeries, and Schneiderian membrane perforation occurred in 202 sinus floor elevations (21.98%) across 168 patients. The main documented causes of perforations, which ranged from 2 to 10 mm in diameter, were the presence of septa, followed by thin and adherent membranes. Of the perforations, 100 (49.5%) were treated with microsurgical suturing combined with fibrin glue, 78 (38.6%) were treated with fibrin glue alone, and 24 (11.9%) were treated exclusively with suturing. Sinus grafting was performed using autogenous bone in combination with a biomaterial, following the layering technique. All surgeries resulted in primary healing without complications, enabling all patients to undergo restoration as planned. The long term clinical and radiological evaluations of 44 randomly selected patients who followed the recall program up to 10 years post operative confirmed the effectiveness of this treatment approach.

Radiofrequency sheath rectification on WEST: application of the sheath-equivalent dielectric layer technique in tokamak geometry*

Abstract Radiofrequency sheath rectification is a phenomenon relevant to the operation of Ion Cyclotron Range of Frequencies (ICRFs) actuators in tokamaks. Techniques to model the sheath rectification on 3D ICRF antenna geometries have only recently become available (Shiraiw et al 2023 Nucl. Fusion 63 026024; Beers et al 2021 Phys. Plasmas 28 093503). In this work, we apply the ‘sheath-equivalent dielectric layer’ technique, used previously only on linear devices (Beers et al 2021 Phys. Plasmas 28 103508), in tokamak geometry, computing rectified sheath potentials on the WEST ICRF antenna. Advancing the state of the art in sheath rectification modeling, we compute the sheath potentials not just on the limiters, but also on the Faraday Screen bars. The calculations show a peak rectified DC potential of 300 V on the limiters and 500 V on the Faraday screen. Assuming a typical sputtering yield curve, the RF sheath rectification increases the sputtering yield from the limiters by a factor of 2.6 w.r.t. the sputtering due to the non-rectified thermal sheath.

Layered MXene Films via Self-Assembly.

MXene has attracted significant attention as a 2D material family due to its metallic conductivity and abundant surface functional groups and has been extensively studied and applied as bulk materials and microscale thin films. MXene possesses ionizable surfaces and edges, as well as high surface area. Its customizable dispersibility demonstrates unique advantages in self-assembly solution processing. Recent studies have demonstrated the application value of layered MXene films at the nanoscale thickness and the reliance of processing on self-assembly techniques. However, this field currently lacks sufficient attention. Here, the regulatory mechanisms are summarized for the preparation of layered MXene films through self-assembly techniques, as well as introduce their applications. Moreover, the future challenges of large-scale applications of MXene self-assembly techniques are proposed. It is believed that this review would provide a dynamic and promising path for the development of layered MXene self-assembly techniques.

Aerobic Oxidation of Alcohol Over Copper(II)‐Based Metal–Organic Framework: Synthesis, X‐Ray Structure, and Catalytic Study

ABSTRACTA copper‐based one‐dimensional framework compound [Cu2(L1)4(L2)]n (1) [L1 = 3‐(2‐thienyl)acrylic acid, L2 = 4,4′‐bipyridine] has been synthesized by slow diffusion of layers technique and characterized by spectroscopic methods and single‐crystal X‐ray crystallography. X‐ray diffraction analysis reveals that the compound is crystallized in the triclinic crystal system with space group Pī. Two neighboring Cu centers are bridged by four carboxylato groups from four different L1 ligands, leading to the formation of a paddle‐wheel [Cu2(COO−)4] secondary building unit (SBU). The paddle‐wheel units are interconnected by bidentate 4,4′‐bipyridine ligands to form a one‐dimensional infinite chain network. In [Cu2(L1)4(L2)]n (1), Cu(II) ion features a penta‐coordinated environment around it. Notably, [Cu2(L1)4(L2)]n (1) is capable of activating molecular oxygen to efficiently catalyze the oxidation of alcohols under base‐free conditions.

Cost-Effective High Gain Wideband Antenna with Dual Partially Reflective Surface for 5G-mmWave Application

This research presents the performance improvement of the of rectangular patch microstrip antenna. The purpose is to increase gain and bandwidth with design on the PRS (Partially Reflective Surface) dual layer technique. There is a developing the low-cost substrate-based antennas suitable for 5G millimeter-wave. The prototype antenna achieves a maximum gain of 11.8 dBi at a frequency of 25.5 GHz. The gain increases by 6 dB throughout its operational frequency range, with an OBW (Overlap bandwidth) of 20.9%, covering frequencies from 24.0 GHz to 29.9 GHz. The performance achieved results indicate that the prototype antenna can be effectively utilized for 5G millimeter-wave communication applications in Thailand.

Clinical, radiographic and biochemical assessment of proximal cavities restored with composite resin using incremental vs. bulk packing techniques: One-year randomized clinical trial

BackgroundBulk-fill resin composites may suffer from recurrent caries around compound proximal restorations in posterior teeth, especially at the proximo-gingival interface.Over 12 months, will the bulk fill technique affect the caries recurrence rate at gingival margins when compared to the conventional incremental packing technique? How early will the first clinical, radiographical, and biochemical evidence of caries recurrence occur?MethodsAfter randomization, in 30 patients with two compound (OM or OD) supragingival lesions, one tooth was restored using the bulk fill technique on one side (group 1) (n = 15). In contrast, the other tooth on the other side was restored utilizing the incremental layering technique (group 2) (n = 15). Both teeth received restorative material (X-tra fil, Voco, Cuxhaven, Germany). The FDI criteria were used to evaluate restorations. As for the periodontal assessment, the gingival index, plaque index, papillary bleeding scoring index and periodontal pocket depth were evaluated. The gingival crevicular fluid (GCF) specimens were gathered, and MMP-9 was extracted and quantitated by ELISA. A customized radiographic template was designed, and 3D printed digital bitewing radiographs were taken. Assessments were done clinically, radiographically and biochemically at baseline (1 week) and after 3, 6 and 12 months. Data was statistically analyzed.ResultsThe null hypothesis was accepted clinically; no statistically significant differences appeared between bulk and incrementally filled posterior restorations. As for the radiographic assessment, the null hypothesis was accepted except for increased periodontal ligament width at 3 months. The null hypothesis for the biochemical evaluation was rejected as there were significant changes in levels of MMP-9 at different testing times.Conclusions1. With similar results but less sensitivity and significant time saving, the bulk fill technique can be considered an efficient alternative to the incremental fill technique in restoring proximal cavities. 2. Early evidence of caries recurrence can be correlated to an increase in the MMP-9 level in gingival crevicular fluid, followed by an increase in radiographic periodontal ligament width measurement.Trial registrationAn ethical approval from the Research Ethics Committee at the Faculty of Dentistry, October 6 University, (Approval No. RECO6U/5-2022). The study was registered at the Pan African Clinical Trials Registry on 24/07/2023 with an identification number (PACTR202307573531455).

Complex Diagnostics of Silicon-on-Insulator Layers after Ion Implantation and Annealing

A technology was developed for activating ion-implanted dopants in silicon-on-insulator layers at a low annealing temperature (600°C) using the pre-amorphization technique of a silicon device layer. In the case of phosphorus implantation, silicon was amorphized directly by dopant ions. In the case of boron implantation for pre-amorphization, the layers were preliminary irradiated with argon or fluorine ions. Complex diagnostics of the implanted layers was carried out using secondary ion mass spectrometry, X-ray diffractometry and small-angle X-ray reflectometry. The combination of methods made it possible to characterize the impurity distribution, the degree of silicon crystallinity, the layer thicknesses, and the interface widths in structures. The results of diagnostics of the structure and composition correlate well with calculations in the SRIM software package and the electrophysical characteristics of the layers after annealing. It was shown that the use of argon for pre-amorphization of silicon interfered with the recrystallization process and did not make it possible to achieve acceptable electrical characteristics of the doped layer. Amorphization with phosphorus and pre-amorphization with fluorine during boron implantation allowed obtaining the required values of the resistance of the doped layers after annealing at a temperature of 600°C. The use of a complex approach made it possible to optimize the modes of amorphization, ion doping, and annealing of silicon-on-insulator structures at low temperatures, necessary for the creation of light-emitting device structures based on silicon-germanium nanoislands.