Biomechanical evaluation of screw and cement placement strategies for treating medial uncontained tibial defects in total knee arthroplasty: A finite element analysis.

Total knee arthroplasty faces challenges in the management of medial uncontained tibial defects, affecting prosthesis stability and implant survival. The use of screws and bone cement is a preferred approach; however, optimal screw insertion techniques lack consensus in the existing literature. The present study aimed to address this gap by exploring optimal screw and cement placement strategies, focusing on their biomechanical implications. The present study conducted a finite element analysis using a knee prosthesis model with a defined uncontained tibial defect. Various parameters were systematically adjusted, including the number of screws (1, 2 or 3 screws), screw lengths (10, 18, 30 or 40 mm), lateral-medial screw positions (2, 4 or 6 mm laterally) and abduction rotation angles (0, 5, 10 or 15 degrees). These adjustments were made to evaluate their specific and combined impacts on the vertical displacement and abduction angles of the tibial tray. The results revealed that incorporating three-screw reinforcement markedly reduced vertical displacement, while the single screw in the middle position exhibited superior performance in preventing the deformation of abduction angles compared to scenarios with two screws at anterior and posterior positions without a middle screw. Longer screws and smaller abduction angles contributed to decreased movement of the tibial component. Furthermore, the lateral adjustment of the screw position led to an increase in vertical displacement values, reaching ~1.5% when shifted 6 mm laterally. On the whole, the finite element analysis in the present study suggests that, for the treatment of medial uncontained tibial defects, three-screw reinforcement is advantageous for larger defects. Longer screws and a smaller abduction angle are deemed favorable. Moreover, the results underscore the superiority of medial screw placement over lateral placement. It is imperative to note that further clinical validation is essential to corroborate the biomechanical implications observed herein.

Curettage of lesion combined with reconstruction of intramedullary nail and bone cement for the treatment of subtrochanteric metastatic tumors of the femur.

This study investigated subtrochanteric femoral metastases using a retrospective approach by analyzing data from 109 patients with bone metastases (2015-2019). Surgical methods were compared: curettage with intramedullary nail and bone cement versus prosthetic reconstruction. Post-surgical assessments included joint function, bone metastasis-related serum markers, and complications. Univariate and multivariate logistic regression analysis was used to screen independent risk factors affecting patients' prognosis. R language was used to construct a nomogram model for predicting patients' 1- and 2-year survival, which was validated through ROC curves and the calibration chart. Patients treated with curettage showed superior postoperative outcomes, exhibiting significantly higher Karnofsky Performance Status (KPS) scores (80.00 vs. 70.00, P < 0.001) and Musculoskeletal Tumor Society Scores (MSTS) (23.86 ± 2.57 vs. 21.67 ± 3.24, P < 0.001). Both methods demonstrated comparable efficacy in pain control (VAS: 3.00 vs. 3.00, P > 0.05) and bone metabolism impact (ALP: 85.93 ± 14.44 vs. 83.19 ± 21.19; CTX-I: 3.03 ± 1.56 vs. 3.15 ± 1.75; PINP: 10.30 ± 4.41 vs. 11.57 ± 3.90; all P > 0.05). Cox regression identified treatment regimen, age, diabetes, and pre-treatment KPS score as significant survival factors (all P < 0.05). The nomogram model demonstrated high accuracy in predicting one-year and two-year survival (AUC: 0.821 and 0.790, respectively). In conclusion, curettage with intramedullary nail and bone cement enhances postoperative functional recovery and quality of life for subtrochanteric femoral metastases patients, representing a promising treatment method.

Recent Advances in Minimally Invasive Management of Osteolytic Periacetabular Skeletal Metastases.

Painful skeletal osteolytic metastases, impending pathological fractures, and nondisplaced fractures present as a devastating clinical problem in advanced stage cancer patients. Open surgical approaches provide excellent mechanical stabilization but are often associated with high complication rates and slow recovery times. Percutaneous minimally invasive interventions have arisen as a pragmatic and logical treatment option for patients with late-stage cancer in whom open surgery may be contraindicated. These percutaneous interventions minimize soft tissue dissection, allow for the immediate initiation or resumption of chemotherapies, and present with fewer complications. This review provides the most up-to-date technical and conceptual framework for the minimally invasive management of osseous metastases with particular focus on periacetabular lesions. Fundamental topics discussed are as follows: (1) pathogenesis of cancer-induced bone loss and the importance of local cytoreduction to restore bone quality, (2) anatomy and biomechanics of the acetabulum as a weight-bearing zone, (3) overview of ablation options and cement/screw techniques, and (4) combinatorial approaches. Future studies should include additional studies with more long-term follow-up to better assess mechanical durability of minimally invasive interventions. An acetabulum-specific functional and pain scoring framework should be adopted to allow for better cross-study comparison.

Primary life cycle inventory data for cement production, with relevance to sustainability assessment-Indian cases.

The data provided is primary data related to cement production collected from the six different cement plants in India. This serves as the inventory for conducting material flow analysis, supply chain forecasting, and life cycle assessment of cement and concrete systems. The dataset is given in three data sheets with information relevant to the steps followed in line with the life cycle assessment (LCA) methodology, i.e., inventory, characterization factors and impacts (here, carbon footprint and energy consumed). The data includes the amounts of raw materials (type and source), the electricity (source and amount) used in the clinker and other products produced, such as OPC (Ordinary Portland Cement), PPC (Portland Pozzolana Cement), PSC (Portland Slag Cement) and GGBS (Ground Granulated Blast Furnace Slag). The data is presented (in Sheet A and C) for the relevant functional unit, i.e., one tonne of material produced in each plant. Sheet B gives one of its kind data related to electricity produced (1 kWh) in the thermal power plant associated with the cement plant, also called as captive power plant. As the cement production process contributes to 8% of the anthropogenic CO2 emissions, it is important to understand the environmental impacts associated with it, and primary data generated are essential for assessing the impacts and to modify the processes with higher contribution to reduce the impacts. This dataset can, therefore, serve as a basis to collect the data from similar plants in any part of the world and benchmarking.

Histological response of inflamed pulp to hydraulic calcium silicate cements in direct pulp capping: Systematic review of pulpitis models.

This systematic review aimed to compare the histological response of inflamed pulpodentinal complex to the hydraulic calcium silicate cements in experimental animal models of pulpitis. Articles that evaluated the histological response of inflamed pulp to mineral trioxide aggregate (MTA) in comparison with other restorative materials were selected and analysed in detail. The risk of bias assessment was conducted using SYRCLE's RoB tool. The GRADEpro tool was used to determine the overall quality of evidence. Out of the 2947 retrieved articles from databases, five articles fulfilled the inclusion criteria. MTA induced significantly more hard tissue formation compared to calcium hydroxide. The use of pulp-capping material containing fluocinolone acetonide and ASP/PLGA-ASP/ACP/PLLA-PLGA composite membrane was comparable. This systematic review could not demonstrate enhanced efficiency of capping materials compared to MTA. Future well-conducted animal studies are warranted for demonstrating the hard tissue formation abilities of pulp-capping materials with convenient inflammatory conditions.

Investigation and performance analysis of eco-friendly coco fiber concrete hybridized with CNT blend.

With the development of the technical trend, concrete using waste alternate material instead of sand material found economic potential for good structural behaviour. Besides, the susceptible crack, low strength-to-weight ratio, and low compressive strength are the reasons for shrinkage. Due to this reason, the investigation aims to limit the shrinkage under live load and increase the compression and flexural strength by the introduction of coconut waste chopped fiber (wCF), waste fly ash (wFA), and carbon nanotube powder (CNT) blended with conventional Portland paste. The developed concrete consists of 5 wt% wCF, 10 wt% wFA, and 0, 5, 10, and 15 wt% of CNT and is subjected to X-ray diffraction analysis, bulk density, compression and flexural strength, and water absorption studies. The X-ray diffraction pattern revealed the wCF, wFA, CNT, and matrix compositions. The concrete developed with 5 wt% wCF, 10 wt% wFA, and 15 wt% CNT cured within 28 days recorded maximum behaviour of compression strength (47 ± 1.8 MPa), flexural strength (4.9 ± 0.19 MPa), and water absorption of (2.8 ± 0.05 %).

Investigating the Impact of Superabsorbent Polymer Sizes on Absorption and Cement Paste Rheology.

This study aims to understand the water retention capabilities of Superabsorbent Polymers (SAPs) in different alkaline environments for internal curing and to assess their impact on the rheological properties of cement paste. Therefore, the focus of this paper is on the absorption capacities of two different sizes of polyacrylic-based Superabsorbent Polymers : SAP A, with an average size of 28 µm, and SAP B, with an average size of 80 µm, in various solutions, such as pH 7, pH 11, pH 13, and cement filtrate solution (pH 13.73). Additionally, the study investigates the rheological properties of SAP-modified cement pastes, considering three different water-to-cement (w/c) ratios (0.4, 0.5, and 0.6) and four different dosages of SAPs (0.2%, 0.3%, 0.4%, and 0.5% by weight of cement). The results showed that the absorption capacity of SAP A was higher in all solutions compared to SAP B. However, both SAPs exhibited lower absorption capacity and early desorption in the cement filtrate solution. In contrast to the absorption results in pH 13 and cement filtrate solutions, the rheological properties, including plastic viscosity and yield stress, of the cement paste with a w/c ratio of 0.4 and 0.5, as well as both dry and wet (presoaked) SAPs, were higher than those of the cement paste without SAP, indicating continuous absorption by SAP. The viscosity and yield stress increased over time with increasing SAP dosage. However, in the mixes with a w/c ratio of 0.6, the values of plastic viscosity and yield stress were initially lower for the mixes with dry SAPs compared to the reference mix. Additionally, cement pastes containing wet SAP showed higher viscosity and yield stress compared to the pastes containing dry SAP.

Chloride Binding Behavior and Pore Structure Characteristics of Low-Calcium High-Strength Cement Pastes.

While Portland cement produces large amounts of carbon dioxide, low-calcium high-strength cements effectively reduce carbon emissions by decreasing the proportion of high-calcium minerals. In order to enhance the practical application value of low-calcium high-strength cement, the effects of mineral admixtures on the chloride binding capacity and pore structure characteristics of low-calcium high-strength cement pastes were investigated by equilibrium method and mercury intrusion method. The results showed that the chloride binding capacity of low-calcium high-strength cement pastes is superior to that of Portland cement. Fly ash and slag enhance this capacity by promoting monosulfoaluminate and C-S-H gel formation, with fly ash being more effective. Ground limestone also boosts chloride binding when incorporated at less than 10 wt%. However, sulfates have a more significant negative impact on chloride binding capacity in low-calcium high-strength cement pastes compared to Portland cement. The porosity of low-calcium high-strength cement pastes exhibits contrasting trends with the addition of fly ash, ground limestone, and slag. Fly ash and limestone initially coarsen the pore structure but later facilitate the transition of larger pores to smaller ones. In contrast, slag initially has little impact but later promotes the conversion of large capillary pores to medium ones, optimizing the pore structure. Notably, above 10 wt% fly ash, the critical pore diameter decreases with additional fly ash except at 10% where it increases for 3 days. Ground limestone enlarges the critical pore diameter, and this effect intensifies with higher content. During early hydration, slag decreases the critical pore diameter, but its impact diminishes in later stages.

Experimental Study on the Strength Deterioration and Mechanism of Stabilized River Silt Reinforced with Cement and Alginate Fibers.

River silt deposited by water in coastal areas is unsuitable for engineering construction. Thus, the in situ stabilization treatment of river silt as the bearing layer has been an important research area in geotechnical engineering. The strength degradation behavior and mechanism of stabilized river silt reinforced with cement and alginate fibers (AFCS) in different engineering environments are crucial for engineering applications. Therefore, freeze-thaw (F-T) cycle tests, wetting-drying (W-D) cycle tests, water immersion tests and seawater erosion tests were conducted to explore the strength attenuation of stabilized river silt reinforced with the same cement content (9% by wet weight) and different fiber contents (0%, 0.3%, 0.6% and 0.9% by weight of wet soil) and fiber lengths (3 mm, 6 mm and 9 mm). The reinforcement and damage mechanism of AFCS was analyzed by scanning electron microscopy (SEM) imaging. The results indicate that the strength of AFCS was improved from 84% to 180% at 15 F-T cycle tests, and the strength of AFCS was improved by 26% and 40% at 30 W-D cycles, which showed better stability and excellent characteristics owing to the hygroscopic characteristics of alginate fiber arousing the release of calcium and magnesium ions within the alginate. Also, the strength attenuation of AFCS was reduced with the increase in the length and content of alginate fibers. Further, the strength of specimens in the freshwater environment was higher than that in the seawater environment at the same fiber content, and the softening coefficient of AFCS in the freshwater environment was above 0.85, indicating that the AFCS had good water stability. The optimal fiber content was found to be 0.6% based on the unconfined compressive strength (UCS) reduction in specimens cured in seawater and a freshwater environment. And the strength of AFCS was improved by about 10% compared with that of cement-stabilized soil (CS) in a seawater environment. A stable spatial network structure inside the soil was formed, in which the reinforcing effect of fibers was affected by mechanical connection, friction and interfacial bonding. However, noticeable cracks developed in the immersed and F-T specimens. These microscopic characteristics contributed to decreased mechanical properties for AFCS. The results of this research provide a reference for the engineering application of AFCS.

Development of Negative-Temperature Cement Emulsified Asphalt Spraying Materials Based on Spraying Performance and Rheological Parameters.

To develop a cement emulsified asphalt composite (CEAC) that can be sprayed under a plateau negative temperature environment, the effects of the water-solid ratio, calcium aluminate cement substitution rate, emulsified asphalt content, sand-binder ratio, and polyvinyl alcohol (PVA) fiber content on the spraying performance and rheological parameters of CEAC were explored through the controlled variable method. Additionally, the correlation between the spraying performance and rheological parameters of CEAC was established, and the optimal proportion of CEAC was determined. Then, the difference in frost resistance and pore structure between the cement slurry (CS) without emulsified asphalt and CEAC at the optimum proportion was analyzed. The results showed that the optimum proportions for sprayed CEAC were 0.14 water-solid ratio, 0.5 sand-binder ratio, 25% substitution of calcium aluminate cement, 5% emulsified asphalt content, and 1.5% PVA fiber volume mixing. The yield stress and plastic viscosity of CEAC were positively correlated with the build-up thickness, whereas the rebound rate and the latter showed a negative correlation. The spraying performance may be described by the rheological parameters; the ranges of yield stress and plastic viscosity of 2.37-3.95 Pa·s and 77.42-108.58 Pa, respectively, produced the best spray ability. After undergoing an equivalent number of freeze-thaw cycles, CEAC exhibited lower mass and strength loss rates compared to CS, thereby demonstrating superior frost resistance. In addition, the pore structure analysis showed that the difference in capillary and macropore contents was the main reason for the variability in frost resistance between CS and CEAC.

The Multifaceted Comparison of Effects of Immobilisation of Waste Imperial Smelting Furnace (ISF) Slag in Calcium Sulfoaluminates (CSA) and a Geopolymer Binder.

Using waste materials as replacements for sand in building materials helps reduce waste and improve the properties and sustainability of the construction materials. Authors proved the possibility of using imperial smelting furnace (ISF) slag granules as a 100% substitute for natural sand in self-compacting (SCC) cement-based mortars of calcium sulfoaluminates (CSA). The study proved that ISF slag's radioactive properties meet this area's requirements. CSA cement eliminates the noted problem in the case of concrete with Portland cement, which is the extended setting of the cement binder. The research findings indicate that using slag to replace sand up to 100% in mortars without grains smaller than 0.125 mm allows high flowability, compaction, low porosity and mechanical parameters. The compressive strength of the CSA cement mortars was about 110 MPa, and more than 140 MPa for geopolymer mortar. Unfortunately, the alkaline pH of a geopolymer causes high leachability of barium and sodium. Thus, the CSA cement is in a more favourable binder to achieve high strength, is environmentally friendly, and is a self-compacting mortar or concrete.

Effect of Exposure Conditions on Mortar Subjected to an External Sulfate Attack.

This study aims to investigate the influence of exposure conditions on the behavior of mortar subjected to an external sulfate attack (ESA). Three different exposure conditions (full immersion, semi-immersion, and drying/wetting cycles) were tested on mortar prisms made with Portland cement and two w/c ratios (0.45 and 0.6). To monitor degradation, it was necessary to evaluate variations in length (expansion), mass changes, compressive and tensile strengths, changes in the total porosity measured using water accessible porosity tests, and changes in the macroscopic behavior of the samples. Mercury intrusion porosimetry (MIP) was used to determine the size distribution of the pores. It was demonstrated that mixing mortar with the lower w/c ratio of 0.45 results in improved performance against an ESA. This study also demonstrates that the type of exposure to an ESA has no significant effect on the kinetics of sulfate penetration during the exposure period. However, the sample's surface becomes more cracked when subjected to repeated drying and wetting cycles. For all the considered exposure conditions, expansion occurred in three stages. In stage 1, the reaction product (ettringite) precipitated in large voids, without causing significant expansion (the expansion remained low and stable). During the second stage, the reaction products generated growing internal stress. The final stage of expansion resulted in microcracks, strength losses, and the formation of macropores, which ultimately lead to material failure. The MIP results indicate that major changes in the porosity and pore volume distribution occur at the surface layer in regard to the gel and capillary pore ranges.

Microcrack and Porosity Development in Sealed Cement Mortars Measured with Micro-Computed Tomography.

For the first time, this paper explores the role of hydration kinetics on microcrack development in cement mortars using the µ-CT technique with a resolution of 2.2 µm. Three binders were tested: fine-grained ordinary Portland cement (OPC) with Blaine fineness of 391 m2/kg, coarse-grained OPC made from the same clinker with Blaine fineness of 273 m2/kg, and H-cement as a representative of the alkali-activated binder. It was found that most microcracks have a width in the range of 5-10 µm, increasing their occurrence with the progress of sealed hydration. While H-cement and coarse-grained OPC showed a comparable number of microcracks, fine-grained OPC exhibited more than twice the number of microcracks. In this sense, high hydration kinetics induce more microcracks, promoting later coalescence into visible cracks and disintegration of concrete at the end. Therefore, durable concrete with minimum microcracks should be derived from slow hydration kinetics or alkali-activation processes.

Optimal Limestone Content on Hydration Properties of Ordinary Portland Cement with 5% Ground Granulated Blast-Furnace Slag.

In this study, the effect of limestone content on the mechanical performance and the heat of hydration of ordinary Portland cement (OPC) was investigated. Changes in the phase assemblage were analyzed through XRD and thermodynamic modeling. The purpose of the study was to identify the optimal limestone content in OPC. As a result of the experiment, all samples were found to have equal fluidity. Increasing the limestone content accelerated the hydration of the cement before approximately 13 h and shortened the setting time due to the acceleration of the initial hydration reaction. The compressive strength of the cement mortar showed a dilution effect, with lower compressive strength compared to the reference sample at an early age, but it gradually recovered at a later age. This is because, as shown in the XRD and thermodynamic modeling results, the carboaluminate phases formed due to the chemical effect of limestone contributed to the development of compressive strength. As a result, within the scope of this study, it is believed that maintaining the limestone content in OPC within 10% is optimal to minimize quality degradation.

Mechanical Properties and Durability of Composite Cement Pastes Containing Phase-Change Materials and Nanosilica.

Escalating global surface temperatures are highlighting the urgent need for energy-saving solutions. Phase-change materials (PCMs) have emerged as a promising avenue for enhancing thermal comfort in the construction sector. This study assessed the impact of incorporating PCMs ranging from 1% to 10% by mass into composite Portland cement partially replaced by fly ash (FA) and nanosilica particles (NS). Mechanical and electrochemical techniques were utilized to evaluate composite cements. The results indicate that the presence of PCMs delayed cement hydration, acting as a filler without chemically interacting within the composite. The combination of FA and PCMs reduced compressive strength at early ages, while thermal conductivity decreased after 90 days due to the melting point and the latent heat of PCMs. Samples with FA and NS showed a significant reduction in the CO2 penetration, attributed to their pozzolanic and microfiller effects, as well as reduced water absorption due to the non-absorptive nature of PCMs. Nitrogen physisorption confirmed structural changes in the cement matrix. Additionally, electrical resistivity and thermal behavior assessments revealed that PCM-containing samples could reduce temperatures by an average of 4 °C. This suggested that PCMs could be a viable alternative for materials with thermal insulation capacity, thereby contributing to energy efficiency in the construction sector.

Factors Influencing Chloride Ion Diffusion in Reinforced Concrete Structures.

Reinforced concrete structures are prone to the corrosion of steel bars when exposed to chloride-rich environments, which can severely impact their durability. To address this issue, a comprehensive understanding of the factors influencing chloride ion diffusion in concrete is essential. This paper provides a summary of recent domestic and foreign research on chloride ion transport in concrete, focusing on six key factors: water-binder ratio, additive content, crack width, ambient temperature, relative humidity, and dry-wet cycles. The findings show that the diffusion coefficient of chloride ions in concrete increases with a higher water-binder ratio and decreases with increased additive content. Additionally, wider cracks result in a greater diffusion of chloride ions. The permeability resistance of concrete to chloride ions decreases with rising temperature and humidity, and dry-wet cycles further accelerate the diffusion of chloride ions. The article concludes by discussing various anti-corrosion measures, such as the use of corrosion inhibitors, surface coatings, and electrochemical treatments, to ensure the longevity of the structure. Finally, directions for future research are proposed.

Study on the Preparation and Compressive Strength of Boron Mud-Based Basic Magnesium Sulfate Cement.

The direct discharge of boron mud poses significant environmental hazards to soil and groundwater. Despite extensive research efforts, the reprocessing of boron mud has not yielded significant advancements. Recently, the development of magnesium cement has spurred interest in the reutilization of boron mud. However, the direct treatment of boron mud remains challenging, necessitating pre-treatment in most studies to achieve substantial results. Consequently, research on the direct incorporation of untreated boron mud is scarce. This study explores the feasibility of using uncalcined boron mud as a base material in basic magnesium sulfate cement (BMSC), composed of lightly calcined magnesia and magnesium sulfate heptahydrate. The effects of varying boron mud content on the compressive strength of the BMSC system were investigated. The results indicate that the 5·1·7 phase is the primary strength phase of BMSC. When the boron mud content is 30%, the uncalcined boron mud has a minimal impact on the formation of the 5·1·7 phase. Additionally, the 28 days compressive strength of BMSC-B30 showed a slight difference compared to the control group BMSC-C, registering at 66.7 MPa. TG-DSC analysis revealed that the presence of a small amount of boron mud inhibits the micro-expansion trend of the BMSC structure. Furthermore, XRD and SEM analyses confirmed that the addition of uncalcined boron mud does not significantly alter the phase structure of the 5·1·7 phase in BMSC. This study provides a foundational basis for the long-term development of direct boron mud treatment.

Cure State Sensing of Polymethylmethacrylate Using a Vibrating Axial Probe.

A new axially vibrating sensor based on an audio voice coil transducer and a lead zirconate titanate (PZT) piezoelectric disc microphone was developed as a probe for the measurement of in vitro rheological fluid properties, including curing progress for polymethylmethacrylate (PMMA) mixtures with important uses as bone cement in the field of orthopedics. The measurement of the vibrating axial sensor's acoustic spectra in PMMA undergoing curing can be described by a damped harmonic oscillator formalism and resonant frequency (ca. 180 Hz) shift can be used as an indicator of curing progress, with shifts to the blue by as much as 14 Hz. The resonant frequency peak was measured in 19 different 4.0 g PMMA samples to have a rate of shift of 0.0462 ± 0.00624 Hz·s-1 over a period of 400 s while the PMMA was in a dough state and before the PMMA transitioned to a hard-setting phase. This transition is unambiguously indicated by this sensor technology through the generation of a distinct circa 5 kHz high-Q under-damped ring-down response.

Biological interaction, esthetics, handling, and loss rate of temporary luting cements - a clinical single-blind randomized controlled trial.

OBJECTIVES: To evaluate three temporary luting cements in terms of their restoration loss rates, biological interactions, esthetic properties, and handling characteristics. MATERIALS AND METHODS: 75 adults requiring fixed prosthodontics voluntarily participated in a single-blind, randomized controlled trial. After preparation, temporary restorations were luted with a randomly selected temporary luting cement (either Provicol QM Plus (PQP), Bifix Temp (BT), or Provicol QM Aesthetic (PQA)). Clinical examinations were performed one to two weeks after cementation. The following criteria were evaluated: tooth vitality, percussion, hypersensitivity, gingival bleeding, odor formation, esthetics, cement handling, removability, cleanability, and retention loss. Antagonistic teeth served as controls. Statistical analysis was performed using the paired t-test, one-way ANOVA, Pearson's chi-square and Fisher's exact test, where appropriate. RESULTS: The overall loss rate of temporary restorations was 16.0%, showing no cement-specific differences. Postoperative hypersensitivity occurred in 8% of cases regardless of cement type. Esthetic impairment was reported by 31% of the PQP-fixed restorations, compared with 4.0% and 4.2% of the BT and PQA-bonded restorations. Cement application was reported to be easy in 100% of cases, excess removal in 88-96%, depending on the cement used. CONCLUSIONS: The choice of luting material affects the esthetic appearance of a temporary restoration and should be considered, particularly in restorations in esthetically demanding areas. No significant differences between the cements were identified regarding biocompatibility, handling, and loss rate. CLINICAL RELEVANCE: Translucent cements can help to reduce color interferences, resulting in a more appealing appearance of the temporary restoration.

Major vault protein is part of an extracellular cement material in the Atlantic salmon louse (Lepeophtheirus salmonis).

Major vault protein (MVP) is the main component of the vault complex, which is a highly conserved ribonucleoprotein complex found in most eukaryotic organisms. MVP or vaults have previously been found to be overexpressed in multidrug-resistant cancer cells and implicated in various cellular processes such as cell signaling and innate immunity. The precise function of MVP is, however, poorly understood and its expression and probable function in lower eukaryotes are not well characterized. In this study, we report that the Atlantic salmon louse expresses three full-length MVP paralogues (LsMVP1-3). Furthermore, we extended our search and identified MVP orthologues in several other ecdysozoan species. LsMVPs were shown to be expressed in various tissues at both transcript and protein levels. In addition, evidence for LsMVP to assemble into vaults was demonstrated by performing differential centrifugation. LsMVP was found to be highly expressed in cement, an extracellular material produced by a pair of cement glands in the adult female salmon louse. Cement is important for the formation of egg strings that serve as protective coats for developing embryos. Our results imply a possible novel function of LsMVP as a secretory cement protein. LsMVP may play a role in structural or reproductive functions, although this has to be further investigated.