Surface Treatment Procedures Research Articles

Comparison of Various Surface Treatment Procedures on the Roughness and Susceptibility to Staining of Provisional Prosthodontic Materials.

Esthetically pleasing temporary prostheses are often necessary for extended periods in a variety of clinical scenarios. Adjustments to the occlusion or margins are commonly needed before cementing the temporary prosthesis. Therefore, it is clinically necessary to repolish the rough surface to avoid biological and esthetic issues associated with rough surfaces. The purpose of this in vitro study was to assess and compare the impact of various polishing protocols on the surface roughness and color stability of three resin materials used for provisional crowns. A total of 150 specimens were fabricated from auto-polymerizing polymethyl methacrylate, bis-acryl composite, and Methyl methacrylate-LC resin using a stainless steel mold. Each material group was divided into five groups (n = 10) based on the applied surface treatment: positive control group (G1): no roughening or surface treatment, Negative control group (G2): acrylic bur-roughened surface without any polishing, the different surface treatment groups of silicon carbide and aluminum oxide stone polishing (G3), diamond-coated rubber twist (G4), and Surface Glaze (G5). An optical profilometer was used to assess the surface roughness of all samples. After undergoing 6000 cycles of thermocycling followed by immersion in a coffee solution for 15 days at 37 °C, color parameters were measured using a spectrophotometer both before and after a storage period to evaluate color differences. A two-way ANOVA test with α = 0.05 significance level was carried out to determine the impacts of both the materials utilized and the polishing protocol. Among the three types of resin examined, the bisacryl group exhibited superior surface quality in positive control groups, while PMMA resin demonstrated higher polishability. The diamond-coated rubber twits resulted in lower Ra values of 0.36 (0.01) µm, 0.52 (0.11) µm, and 0.28 (0.05) µm for PMMA, BAMA, and MMLC resins, respectively. The application of photo-polymerized surface glaze led to a plaque accumulation threshold of 0.2 µm across all resin groups. The greatest mean color change occurred in the negative control group, indicating a propensity for more staining on rougher surfaces. The Bisacryl resin exhibited higher ΔE values, whereas PMMA showed better color stability. The lowest ΔE values were found when the surface glaze was applied to all of the provisional crown resins. Untreated Bisacryl resin exhibited the lowest Ra values, while PMMA resins demonstrated superior surface morphology after polishing. PMMA provisional crown resins showed increased resistance to staining. The use of surface glaze enhanced both smoothness and color stability on the surfaces.

Optimizing Sample Preparation for Destructive Testing in Resistance Spot Welding

Abstract The integrity and reliability of resistance spot welding, a crucial process in various manufacturing industries, are significantly influenced by the quality of sample preparation. This study focuses on advancing the methodologies and practices in the preparation of samples for resistance spot welding destructive tests, aiming to improve the precision and repeatability of the results. We discuss comprehensive approaches encompassing material selection, surface treatment, dimensional accuracy, and alignment procedures, emphasizing the importance of meticulous handling and preparation techniques, A significant focus is placed on the utilization of sophisticated alignment and measurement tools to enhance the consistency of the welding area subjected to destructive testing. our study demonstrates a significant improvement in the reliability and accuracy of welding machine calibration, ultimately contributing to the overall quality of the welding process. By integrating these refined processes, the study highlights a significant improvement in the reliability of welding tests, contributing to enhanced welding quality and performance in practical applications. Our findings underscore the critical role of detailed and standardized sample preparation in achieving accurate and reliable resistance spot welding destructive test outcomes, providing valuable insights for both industrial applications and further research in welding technology.

Effect and performance analysis of different surface treatments on polymer-metal friction pairs

The reliability of machinery can be directly impacted by severe wear and failure of joint bearings, particularly under harsh operating conditions or after prolonged use. The study aimed to investigate the impact of various surface treatments on the properties of materials using a disc-disc contact friction machine to simulate working conditions similar to those experienced by joint bearings. The application of chrome plating resulted in a significant enhancement in performance, leading to a 20% reduction in the coefficient of friction and an 80% decrease in the wear rate to 0.071 and 1 × 10−5 mm3/(N·m), respectively, at 30 MPa and 42 mm/s. Additionally, it increased the bonding of the transfer film base by 20% compared to untreated specimens, as indicated by nano-scratch tests. On the one hand, the elevated hardness of the chrome-plated coating facilitates uniform load distribution, while on the other hand, the presence of microcracks on the surface aids in retaining a greater amount of abrasive debris and in the formation of a more effective transfer film. Consequently, this diminishes the wear of the polymer material. This discovery has the potential to influence the improvement of surface treatment procedures and the selection of materials for the advancement of engineering practices.

Fine-Tuning the Nanostructured Titanium Oxide Surface for Selective Biological Response.

Cardiovascular diseases are a pre-eminent global cause of mortality in the modern world. Typically, surgical intervention with implantable medical devices such as cardiovascular stents is deployed to reinstate unobstructed blood flow. Unfortunately, existing stent materials frequently induce restenosis and thrombosis, necessitating the development of superior biomaterials. These biomaterials should inhibit platelet adhesion (mitigating stent-induced thrombosis) and smooth muscle cell proliferation (minimizing restenosis) while enhancing endothelial cell proliferation at the same time. To optimize the surface properties of Ti6Al4V medical implants, we investigated two surface treatment procedures: gaseous plasma treatment and hydrothermal treatment. We analyzed these modified surfaces through scanning electron microscopy (SEM), water contact angle analysis (WCA), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analysis. Additionally, we assessed in vitro biological responses, including platelet adhesion and activation, as well as endothelial and smooth muscle cell proliferation. Herein, we report the influence of pre/post oxygen plasma treatment on titanium oxide layer formation via a hydrothermal technique. Our results indicate that alterations in the titanium oxide layer and surface nanotopography significantly influence cell interactions. This work offers promising insights into designing multifunctional biomaterial surfaces that selectively promote specific cell types' proliferation─which is a crucial advancement in next-generation vascular implants.

Influence of clinical zirconia surface treatments on microscopic characteristics and adhesion-proliferation behavior of human gingival fibroblasts

Zirconia is favored in dental implant applications due to its biocompatibility, mechanical properties, and esthetic appeal, particularly in its interaction with soft oral tissues such as the gingiva. To optimize zirconia for clinical use, surface treatments like sanding and polishing are essential. The aim of this study was to investigate the effects of clinical surface treatments on the microscopic characteristics of zirconia and the adhesion and proliferation of human gingival fibroblasts (HGFs). Scanning electron microscopy (SEM) and fluorescence microscopy were utilized to examine the microscopic morphology and roughness resulting from various clinical surface treatment procedures on zirconia and to assess their impact on the microscopic appearance and behavior of HGFs. The results showed that the application of surface treatment procedures, particularly polishing treatments, resulted in the formation of a regular shallow groove morphology and a significant reduction in roughness in zirconia. This was accompanied by improved cell proliferation, cell adhesion, and the expression of integrin β1 in HGFs. The results suggest that smoother zirconia surfaces promote better cell-material interactions, potentially improving the clinical success of dental implants. This research contributes to our understanding of the optimal surface roughness for soft tissue adhesion and the effect of different micro-morphologies on HGF attachment.

Surface modification of polycaprolactone nanofibers through hydrolysis and aminolysis: a comparative study on structural characteristics, mechanical properties, and cellular performance

Hydrolysis and aminolysis are two main commonly used chemical methods for surface modification of hydrophobic tissue engineering scaffolds. The type of chemical reagents along with the concentration and treatment time are main factors that determine the effects of these methods on biomaterials. In the present study, electrospun poly (ℇ-caprolactone) (PCL) nanofibers were modified through hydrolysis and aminolysis. The applied chemical solutions for hydrolysis and aminolysis were NaOH (0.5–2 M) and hexamethylenediamine/isopropanol (HMD/IPA, 0.5–2 M) correspondingly. Three distinct incubation time points were predetermined for the hydrolysis and aminolysis treatments. According to the scanning electron microscopy results, morphological changes emerged only in the higher concentrations of hydrolysis solution (1 M and 2 M) and prolonged treatment duration (6 and 12 h). In contrast, aminolysis treatments induced slight changes in the morphological features of the electrospun PCL nanofibers. Even though surface hydrophilicity of PCL nanofibers was noticeably improved through the both methods, the resultant influence of hydrolysis was comparatively more considerable. As a general trend, both hydrolysis and aminolysis resulted in a moderate decline in the mechanical performance of PCL samples. Energy dispersive spectroscopy analysis indicated elemental changes after the hydrolysis and aminolysis treatments. However, X-ray diffraction, thermogravimetric analysis, and infrared spectroscopy results did not show noticeable alterations subsequent to the treatments. The fibroblast cells were well spread and exhibited a spindle-like shape on the both treated groups. Furthermore, according to the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the surface treatment procedures ameliorated proliferative properties of PCL nanofibers. These findings represented that the modified PCL nanofibrous samples by hydrolysis and aminolysis treatments can be considered as the potentially favorable candidates for tissue engineering applications.

Surface Modified Synthetic Plastic Aggregate for Concrete – Experimental and Analytical Studies

In order to reduce the plastic waste accumulation, and also to decrease consumption volume of natural resources for concrete production, in this paper, an attempt is made to produce novel lightweight coarse aggregate using PET based plastic waste. Use of plastic aggregate normally reduces the strength of concrete primarily due to smoother surface and poor bonding with adjacent cement matrix. Towards improving the bonding characteristics with cement matrix, different surface treatment procedures employing dispersion of sand and ceramic waste particles were tried. Experimental study consisted of using different percentages of plastic aggregate as partial replacement for conventional coarse aggregate. The mechanical properties of concrete such as workability, density, compressive strength and flexural-tensile strength were determined. Correlations studies to predict the concrete strength based on percentage of replacement, and equation relating compressive and flexural-tensile strengths of the concrete were also conducted. The studies indicated that it is possible to improve the bonding property of plastic aggregate for achieving strength and integrity similar to that of control concrete.

Ageing-resistant bonding on stainless steels by laser treatment followed by flame silicatization

In many technological areas, especially in the medical sector, stainless steel parts are being used due to their longevity, good biocompatibility, and high resistance against hygrothermal conditions related to sterilization procedures. Numerous medical products include an adhesive bond that have to reliably withstand these harsh conditions encountered, for example, during autoclaving. However, well established adherent treatment procedures require hazardous chemicals or are not suitable for small fragile parts, for example, components of endoscopes. Therefore, efficient alternatives are necessary. This publication thus presents a combined surface treatment procedure of laser ablation/structuring and flame silicatization. The investigations demonstrate that the resistance to hygrothermal ageing of stainless steel adhesive joints can be significantly increased by pulsed laser irradiation. However, a drastic improvement can only be achieved when the laser fluence exceeds a certain threshold value and, in addition, a nanoporous oxide layer with a reduced chromium content is formed. For substrates of this surface type, ageing resistance can be increased even further by subsequent flame silicatization treatment. The combined methods have proven to be superior as compared to well established processes like sand blasting and coating or corundum blasting.

Repair bond strength of different CAD-CAM ceramics after various surface treatments combined with laser irradiation.

The aim of this study was to evaluate the effect of different surface treatments combined with laser irradiation on the shear bond strength of different CAD-CAM ceramics to composite resin. A total of hundred forty-seven ceramic specimens with thicknesses of 2.5mm were prepared from three different CAD-CAM ceramics (an yttrium oxide partially stabilized tetragonal zirconia polycrystal (Y-TZP); a zirconia-reinforced lithium silicate glass ceramic (ZLS); and a lithium disilicate-strengthened lithium aluminosilicate glass ceramic (LD-LAS)) and subjected to seven groups of treatment (n = 7): (1) control (no treatment), (2) Er:YAG laser irradiation, (3) Nd:YAG laser irradiation, (4) etching with hydrofluoric acid (HFA), (5) Er:YAG + HFA, (6) Nd:YAG + HFA, and (7) sandblasting. After surface treatment procedures, a ceramic primer (Clearfil Ceramic Primer Plus, Kuraray, Japan) was applied to the ceramics. Bonding agent (Single Bond Universal Adhesive, 3M ESPE, USA) was then applied, and the composite resin (Estelite Sigma Quick, Kuraray, Japan) was layered on the ceramic surfaces. The shear bond strength test was performed using a universal testing machine at a load of 0.5mm/min. Data were analyzed by 2-way analysis of variance (ANOVA), and the Bonferroni correction was used for pairwise comparisons (α = 0.05). Compared to the bond strength of the control group, irradiation by Er:YAG and Nd:YAG lasers alone improved the bond strength of the composite resin to the Y-TZP (P < 0.001) but did not change the bond strength of composite resin to the ZLS and LD-LAS (P > 0.05). Compared to the bond strength of the control group, etching with HFA alone increased the bond strength of the composite resin to the ZLS and LD-LAS (P < 0.001) but did not affect the bond strength of the composite resin to the Y-TZP (P > 0.05). The highest bond strength of ZLS was obtained using HFA + Er:YAG, and the highest bond strength for LD-LAS was obtained using HFA + Nd:YAG. It was concluded that Er:YAG and Nd:YAG laser treatments presented the highest repair bond strength between the composite resin and Y-TZP ceramics. Er:YAG and Nd:YAG laser treatments in conjuction with HFA presented the highest repair bond strength between the composite resin and the glassy ceramics, ZLS, and LD + LAS.

Electrochemically Stable Ligands of ZnO Electron-Transporting Layers for Quantum-Dot Light-Emitting Diodes

Thin films of ZnO nanocrystals are actively pursued as electron-transporting layers (ETLs) in quantum-dot light-emitting diodes (QLEDs). However, the developments of ZnO-based ETLs are highly engineering oriented and the design of ZnO-based ETLs remains empirical. Here, we identified a previously overlooked efficiency-loss channel associated with the ZnO-based ETLs: i.e., interfacial exciton quenching induced by surface-bound ethanol. Accordingly, we developed a general surface-treatment procedure to replace the redox-active surface-bound ethanol with electrochemically inert alkali carboxylates. Characterization results show that the surface treatment procedure does not change other key properties of the ETLs, such as the conductance and work function. Our single-variable experimental design unambiguously demonstrates that improving the electrochemical stabilities of the ZnO ETLs leads to QLEDs with a higher efficiency and longer operational lifetime. Our work provides a crucial guideline to design ZnO-based ETLs for optoelectronic devices.

Comparative evaluation of shear bond strength of orthodontic brackets bonded to three-dimensionally-printed and milled materials after surface treatment and artificial aging.

This study aimed to evaluate the shear bond strength (SBS) of orthodontic brackets bonded to three-dimensionally (3D)-printed materials after various surface treatments and artificial aging compared with that bonded to computer-aided design/computer-aided manufacturing (CAD-CAM) polymethyl methacrylate (PMMA)-milled materials. Eighty cylindrical specimens were 3D printed and divided into the following four subgroups (n = 20 each) according to the surface treatment and artificial aging procedure. Group A, sandblasted with 50 μm aluminum oxide particles (SA) and aging; group B, sandblasted with 30 μm silica-coated alumina particles (CO) and aging; group C, SA without aging; and group D, CO without aging. For the control group, 20 CAD-CAM PMMA-milled cylindrical specimens were sandblasted with SA and aged. The SBS was measured using a universal testing machine (0.25 mm/min), examined at ×2.5 magnification for failure mode classification, and statistically analyzed (p = 0.05). The retention obtained with the 3D-printed materials (groups A-D) was higher than that obtained with the PMMA-milled materials (control group). However, no significant difference was found between the study and control groups, except for group C (SA without aging), which showed significantly higher retention than the control group (PMMA-SA and thermocycling) (p = 0.037). Study groups A-D predominantly exhibited a cohesive specimen mode, indicating specimen fracture. Orthodontic brackets bonded to 3D-printed materials exhibit acceptable bonding strengths. However, 3D-printed materials are prone to cohesive failure, which may result in crown fractures.

Roughness of the Surface of Zirconia Reinforced Lithium Disilicate Ceramic Treated by Different Procedures.

Lithium disilicate and zirconia are the two most popular materials for aesthetic and dental prosthetic work; however, due to their limitations, a new material is being researched, namely zirconia-reinforced lithium disilicate, the surface of which is treated with different procedures to achieve the best possible surface properties. In this study, the surface of zirconia-reinforced lithium disilicate glass-ceramic was treated using different methods (conventional and laser) to determine the effects of the treatment procedures on the surface properties and surface roughness to achieve a higher strength of adhesion from the self-adhesive resin cement to zirconia-reinforced lithium disilicate. The treated surfaces were investigated using profilometry, X-ray diffraction and energy dispersive X-ray fluorescence. The results obtained were statistically evaluated. The results show that the surface roughness is highest for the samples treated with Er:YAG (erbium-doped yttrium aluminium garnet laser) and silanisation. Furthermore, the surface treatment procedures applied did not change the composition of the surface.

Quantitative evaluation of surface cleanliness of weathering steel treated by continuous wave laser

A 3 kW continuous-wave (CW) laser was used for the laser cleaning of weathering steel with artificial corrosion pits. Specimens with different degrees of corrosion were obtained by NaCl deposition in artificial pits of 10 mg/m2, 100 mg/m2 and 1000 mg/m2 through constant dew point dry and wet cycles for one year. To develop quantitative evaluation methods that can be applied on-site, the cleanliness of the laser-cleaned surface was evaluated through visual observation, turning time, and photographic analysis. The results reveal that the photometric analysis based on the CIE L*a*b* color space can be used to evaluate the surface cleanliness of surfaces treated with a CW laser, which is consistent with the results of the turning time test. The color difference of the surface before and after the laser treatment can be used as a quantitative index to evaluate cleanliness. The proposed laser surface treatment procedures can provide a reference for cleaning corroded weathering steel structures and achieve cleanliness of more than 80 % and a longer turning time.

Evaluating the color stability of two esthetic ceramic materials after different surface treatments and accelerated aging procedures

Aim: Observing and evaluating the long/short-term discoloration tendency of the esthetic prosthetic materials of lithium disilicate-based glass-ceramics (IPS e.max CAD LT) and leucite-based feldspathic glass-ceramics (VITA Mark II) materials, which are esthetically very close to each other at first glance.&#x0D; Methodology: 80 samples of A2 colored lithium disilicate and feldspathic blocks samples were overglazed and polished separately to evaluate the surface treatment procedures according to CIELAB color coordinates. For accelerated aging purposes, half of the examples were treated to red wine, and the other half were treated to coffee. Color changes were calculated using the ΔE formula. The results were put into record as ΔE-1, ΔE-2, and ΔE-3. Records of the results were evaluated using IBM SPSS Statistics Standard Concurrent User V 25 statistics package program. Data distribution regarding numerical variety and changes were evaluated using the Shapiro Wilk normality test and Q-Q graphics. &#x0D; Results: The data was evaluated using O'Brien clinical color tolerance scales. None of the samples has shown a perfect (ΔE=0-0.5) color match after 4 weeks of accelerated aging. Every group has shown results of significant statistical changes at various rates and percentages and divided into 4 subgroups as excellent, good, clinically acceptable and incompatible categories.&#x0D; Conclusion: Since aging procedures affect ceramic systems' ΔE values in a variety of ways, the aging protocol utilizing in vitro aging techniques for color changing should be evaluated alongside ceramic type and surface finishing procedures.

Direct visualization of the drug release process of non-conductive polymeric implants via molecular imaging

Long-acting parenteral (LAP) implant has garnered the attraction as a drug delivery technique in recent years. Understanding the drug release process is critical for the study of underlying release mechanism. In this paper, we present a novel application of matrix-assisted laser desorption/ionization-mass spectrometry imaging (MADLI-MSI) for the direct visualization of the drug release process from non-conductive polymeric based LAP implants at molecular level. Custom-made sample holders were designed for LAP sample introduction in place of traditional conductive glass slides. The main technical obstacles of applying MALDI-MSI to study non-conductive materials are surface conductivity which can lead to charge build-up. In order to obtain homogeneous imaging of non-conductive sample surfaces, we developed a new sample surface treatment procedure, which is a critical control step to ensure the data reliability and accuracy in understanding kinetics of drug release process of LAP. Overall, this is the first comprehensive report of a sample preparation methodology tailored for imaging LAP at molecular level, allowing for the direct chemical identification and 2D mapping of an active pharmaceutical ingredient (API) distribution during LAP release process. Furthermore, this work has established the foundation to apply MALDI-MSI to the understanding of LAP implant formulation homogeneity, chemical composition, and degradation. More importantly, this work enabled the extension of MALDI-MSI technique to study a wide range of non-conductive materials.

Low radioactive material screening and background control for the PandaX-4T experiment

PandaX-4T is a ton-scale dark matter direct detection experiment using a dual-phase TPC technique at the China Jinping Underground Laboratory. Various ultra-low background technologies have been developed and applied to material screening for PandaX-4T, including HPGe gamma spectroscopy, ICP-MS, NAA, radon emanation measurement system, krypton assay station, and alpha detection system. Low background materials were selected to assemble the detector. Surface treatment procedures were investigated to further suppress radioactive background. Combining measured results and Monte Carlo simulation, the total material background rates of PandaX-4T in the energy region of 1–25 keVee are estimated to be (9.9 ± 1.9) × 10−3 mDRU for electron recoil and (2.8 ± 0.6) × 10−4 mDRU for nuclear recoil. In addition, natKr in the detector is estimated to be < 8 ppt.

Modeling and Analysis of Automotive Engine Crankshaft Made of Composite and Functionally Graded Materials

With the consistent advancement and technical improvisation in the automobile industry, the researchers are working on the material optimization techniques to select and utilize the materials effective in power transmission. It is well know that power transmission systems in the mechanical industries and, namely, in automotive machinaries, require a durable material with proper properties to ensure the optimum operational conditions during power transmission. The material utilized in the driving shaft must have a proper endurance and considerable yielding limit that means they have that ability to sustain the fatigue in the power transmission elements. The method of study is that engine shafts are a major part of the automobiles and the production of these shafts is an important requirement for the resistance against bending and torsion. The torsion and bending resisting moments are important before selecting the material. As a result, selecting the optimal material and surface treatment procedure to offer the highest performance for the shaft is crucial. Wear resistance and corrosion resistance are the two most important factors to consider when selecting a material for a surface. This paper is able to show the effect of materials of the crankshaft on those two elements. The research discusses the shafts of three different types of materials: homogeneous, composite, and functionally graded materials (FGM). For the optimum performance of the vehicle engine shaft, FGM is the ideal material to consider. It has been shown that the performance of crankshaft was improved in case of FGM. Based on the results of the modal and harmonic analysis, it is concluded that FGM crankshaft would offer the best durability and show optimum performance when compared with the other two material crankshafts investigated in this study.

Flexible White Lighting Fabricated With Quantum Dots Color Conversion Layers Excited by Blue Organic Light-Emitting Diodes

In this study, HATCN is coated on flexible PET/indium tin oxide (ITO) substrate as a modified layer and a hole injection layer to improve the hole injection from ITO. Then a blue organic light emitting diode (OLED) can successfully be fabricated without a surface treatment procedure (O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> plasma or UV Ozone treatment). The new blue TADF series fluorescent material is employed as emitting layer with a luminescence wavelength of 456 nm. Also, it has a narrow full width at a half maximum (FWHM) of 26 nm featuring excellent color chromaticity. Quantum dot (QD) photoresist is a perfect color conversion material featuring good color adjustability, narrow emission spectrum, high luminous efficiency, and simple spin-coating processes. In this study, the photoresist mixed with green and red quantum dots is used as a color conversion layer (CCL), and a blue OLED is utilized to excite green and red CCL. To test the material of QD photoresist, it is coated on the substrate of another piece of glass first and then the blue OLED is utilized to remotely excite green and red QD CCL. The fluorescence characteristic of QD photoresist is explored to acquire a spectrum of 528 nm and 620 nm. In the device structure of a blue OLED, the electron-and hole-only current density is compared and the hole transport layer TAPC thickness is adjusted to improve the luminance and efficiency. Finally, green and red quantum dot photoresist is mixed using a proper ratio and then directly coated on the back of the PET/ITO substrate. Furthermore, the thickness of the QD photoresist is adjusted to increase the QD excited fluorescence. The blue OLED and QD CCL was integrated to generate three primary colors, i.e., blue, green, and red. Finally, a flexible white OLED lighting panel is successfully fabricated using simple processes. Moreover, it features high-spectrum stability. The CIE coordinates will not drift with bias, thus, it can resist the voltage variation.

Factors Affecting Sorption and Solubility of Denture Base Acrylic Materials: A Review

Heat-cured PMMA is one of the most frequently used materials in the manufacture of removable dentures. Heat-cured material used to fabricate dentures contain soluble elements, allowing the material to absorb and release substances. These factors all directly affect the longevity and performance of protheses fabricated from polymethyl methacrylate denture base material. Various procedures associated with fabrication of removable dentures from heat-cure denture base material are reported to significantly influence the sorption and solubility experienced by the prosthesis. A comprehensive search of peer-reviewed journals located within academic databases was conducted to identify relevant literature pertaining to sorption and solubility of denture base materials. Key aspects of each paper were captured in Microsoft® Excel® to record author/s, location, study design, sample size, methodology, results and conclusions. Mixing ratios and polymerisation cycles have been identified as variables that can negatively influence the rate of sorption and solubility of denture base materials during the fabrication process. Certain surface treatment procedures, as well as storing the denture in artificial saliva solution may reduce the levels of sorption and solubility experienced and optimise its lifespan. In this review we identify these factors and consider the detrimental effects of sorption and solubility on denture base acrylic materials.

In vitro response of THP-1 derived macrophages to antimicrobially effective PHMB-coated Ti6Al4V alloy implant material with and without contamination with S. epidermidis and P. aeruginosa

AimPeriprosthetic joint infections are a devastating complication after arthroplasty, leading to rejection of the prosthesis. The prevention of septic loosening may be possible by an antimicrobial coating of the implant surface. Poly (hexamethylene) biguanide hydrochloride [PHMB] seems to be a suitable antiseptic agent for this purpose since previous studies revealed a low cytotoxicity and a long-lasting microbicidal effect of Ti6Al4V alloy coated with PHMB. To preclude an excessive activation of the immune system, possible inflammatory effects on macrophages upon contact with PHMB-coated surfaces alone and after killing of S. epidermidis and P. aeruginosa are analyzed.MethodsTHP-1 monocytes were differentiated to M0 macrophages by phorbol 12-myristate 13-acetate and seeded onto Ti6Al4V surfaces coated with various amounts of PHMB. Next to microscopic immunofluorescence analysis of labeled macrophages after adhesion on the coated surface, measurement of intracellular reactive oxygen species and analysis of cytokine secretion at different time points without and with previous bacterial contamination were conducted.ResultsNo influence on morphology of macrophages and only slight increases in iROS generation were detected. The cytokine secretion pattern depends on the surface treatment procedure and the amount of adsorbed PHMB. The PHMB coating resulted in a high reduction of viable bacteria, resulting in no significant differences in cytokine secretion as reaction to coated surfaces with and without bacterial burden.ConclusionTi6Al4V specimens after alkaline treatment followed by coating with 5–7 μg PHMB and specimens treated with H2O2 before PHMB-coating (4 μg) had the smallest influence on the macrophage phienotype and thus are considered as the surface with the best cytocompatibility to macrophages tested in the present study.