Search

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to enhance the physical properties of water-based polyacrylate varnishes, a green-modified water-based nano-Al2O3 dispersion was successfully prepared by regulating the content of anti-sedimentation dispersant under the condition of ultrasonication. The results prove that the prepared water-based nano-Al2O3 dispersion is obtained under the condition of 0.4 wt% anti-sedimentation dispersant and 0.5 h ultrasonic time and storage stability is observed more than 3 months. After adding water-based nano-Al2O3 dispersion at 0.5 wt% mass fraction to water-based polyacrylate varnishes bought from Carpoly, the scratch load is increased from 900 to 1500 g. The analysis of scratch surface appearance also reveals that the damage of water-based polyacrylate/Al2O3 nanocomposites film is minimal. An easy green non-covalent surface modification of commercial nano-Al2O3 was carried out by using anti-sedimentation dispersant (alkylol ammonium salt of acidic polymer) and ultrasonication technology simultaneously, resulting in the formation of a highly well-stable dispersion reported firstly in water and good scratch resistance for water-based polyacrylate varnishes. [ABSTRACT FROM AUTHOR]

Background: Varnish is used in many domains to enhance wear resistance, mechanical behaviour or chemical resistance. To characterize varnish cohesion or adhesion on plane surface, a scratch-test is predominantly used. In order to investigate coating properties on fibres, the common method uses tensile tests. Objective: The aim of this paper was to investigate the adhesion of varnish on a monofibre of polyamide using an out of the box procedure based on scratch tests. To do so, a specific device was conceived to enable a scratch test on a single fibre. Methods: Adhesion between varnish and a monofibre of nylon was investigated using several series of scratch tests on fibres coated by two types of varnish. Coating toughness and adhesion were investigated according to the coating composition and thermal treatment. A comparison between the different prints was discussed to characterize the effect of varnish type on the scratch resistance and to determine the parameters that influence this adhesion using scratch-test. Results: The obtained results highlighted the influence of the thermal treatment imposed to the fibres on the mechanical behaviour. Tensile tests were conducted on the three types of samples in order to establish a link in terms of classification between a well-known characterization experiment and the presented scratch test. Conclusion: Beyond the investigation of varnish/nylon fibre adhesion, this paper mostly aims at validating an innovative process for the characterization of coatings deposited on curved surfaces like fibres. [ABSTRACT FROM AUTHOR]

The use of organic solvents considerably widens the possibilities for the conservation treatment of historic beeswax artifacts, e.g. the choice of effective cleaning methods, adhesives, consolidants, and varnishes. However, their use should always be considered carefully, since most of them dissolve at least some components of the original material. In an attempt to help conservators make well-informed decisions in this respect, the interactions of selected organic solvents with beeswax under various conditions were studied. Besides the importance of solvent type, the most carefully studied aspects were the effect of temperature, exposure duration, and the relative amount of solvent used. The surface action of the solvents on beeswax was monitored by optical microscopy, and the dissolved fraction of the individual components of beeswax was measured both quantitatively, using gravimetry, and qualitatively, using the GC-MS method. It was confirmed that all of the selected organic solvents dissolve beeswax to a certain extent. The authors believe, however, that by optimizing working conditions, the use of some of these solvents can be relatively safe and justifiable in many situations. [ABSTRACT FROM AUTHOR]

Copyright of Virtual Archaeology Review is the property of Virtual Archaeology Review and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Non-diffuse materials (e.g., metallic inks, varnishes, and paints) are widely used in real-world applications. Accurate spectral rendering relies on the bidirectional reflectance distribution function (BRDF). Current methods of capturing the BRDFs have proven to be onerous in accomplishing quick turnaround time, from conception and design to production. We propose a multi-layer perceptron for compact spectral material representations, with 31 wavelengths for four real-world packaging materials. Our neural-based scenario reduces measurement requirements while maintaining significant saliency. Unlike tristimulus BRDF acquisition, this spectral approach has not, to our knowledge, been previously explored with neural networks. We demonstrate compelling results for diffuse, glossy, and goniochromatic materials. [ABSTRACT FROM AUTHOR]

The scoping review objectives were to: 1) investigate the caries preventive potential of professionally deliverable fluoride (F)-containing agents with incorporated arginine (Arg); and 2) identify the future scope of research on Arg-F interventions for caries prevention. Of 150 identified records, 7 articles (6 in vitro investigations and 1 scoping review) were included for a complete review; with no clinical studies with/without appraisal. Arginine variants (L-Arg/Arg.HCl at 1% to 10% w/v.) were examined for a potential professional application aimed at caries prevention, as reported with in vitro studies. Of the included articles, four in vitro studies explored L-Arg enriched 5% NaF varnish (Duraphat®) as a promising caries preventive agent, while only one considered incorporating L-Arg in MI varnish®/nanohydroxyapatite and one investigated glass ionomer cement for primary/secondary and tertiary caries prevention. The scoping review highlighted the scope for incorporating Arg to professionally deliverable F-containing agents. No clinical data are available to make conclusive recommendations about the caries preventive potential of professionally deliverable F-containing agents with incorporated Arg. With Arg-F varnish being investigated predominantly through in vitro studies, the data so far suggest that Arg was incorporated exclusively in Duraphat®, while the potential of Arg to prevent caries in other F-containing varnishes remains unexplored. [ABSTRACT FROM AUTHOR]

Background: Dentin hypersensitivity (DH) is one of the most common conditions clinicians encounter in clinical practice. New techniques are continuously being set forth to treat this condition. In recent times, casein phosphopeptide-amorphous calcium phosphate (CPPACP) has garnered attention owing to its ability to improve remineralization and prevent enamel demineralization. Consequently, it has been indicated as an advanced treatment for DH. Purpose: This clinical trial aims to assess the efficacy of a CPP-ACP varnish in the management of non-carious cervical hypersensitivity and compare it with that of a dentin desensitizer. Methods: Patients between the ages of 20 and 65 years who reported to our institute with complaints of DH were selected for this study. Forty teeth were chosen for this study and randomly assigned to two groups. The test group was treated with a CPP-ACP varnish (MI Varnish®, GC Corporation, Japan), while the control group was treated with a dentin desensitizer (Gluma®, Heraeus-Kulzer, Germany). Dentin hypersensitivity assessments were conducted during pre-treatment, immediately following treatment, and 2 and 4 weeks after treatment. Statistical analysis was performed after data collection. Results: An intragroup comparison showed both the CPP-ACP varnish and the dentin desensitizer achieved a maximum decrease in sensitivity in the time interval from baseline to post-op, and these desensitizing effects were sustained through the second and fourth week following treatment. An intergroup comparison revealed no statistically significant difference in sensitivity between the two groups at different time intervals. Conclusion: It could be concluded that CPP-ACP varnish and dentin desensitizer possess similar efficacy in the treatment of DH. [ABSTRACT FROM AUTHOR]

This study aimed to clarify the effects of high-concentration fluoride varnish application on the inhibition of the progression of initial enamel caries. Remineralization capacity and acid resistance following high-concentration fluoride varnish application were compared with untreated models and models treated with fluoride mouthwash. Bovine enamel was used to create a model of initial enamel caries. The high-concentration fluoride varnishes Enamelast and Clinpro White Varnish and the fluoride mouthwash Miranol were used. Specimens were evaluated using Contact Microradiography (CMR) and an Electron Probe Micro-Analyzer (EPMA). While a single application of high-concentration fluoride varnish and short-term fluoride mouthwash use did not appear to cause remineralization in the subsurface demineralized layer, improvements in acid resistance were observed, leading to reduced demineralization under subsequent acidic challenges. [ABSTRACT FROM AUTHOR]

Ethanol production by fermentation results in obtaining, in addition to the main product, ethyl alcohol, by-products and secondary products, which include carbon dioxide, fusel oil, and ester–aldehyde cut. Fusel oil, despite its low yield and the large volume of ethanol production, accumulates at distilleries, which ultimately raises the question of its disposal or the rational use of this by-product. Fusel oil, being a complex mixture, can serve as a source of technical alcohols used in various sectors of the economy, including the food industry, pharmaceuticals, organic synthesis, perfume, and cosmetics industries, as well as the production of paints and varnishes. However, the complexity of using fusel oil lies in its difficult separation. The reason for this is the presence of water, which forms low-boiling azeotropes with aliphatic alcohols. Our study aimed to develop a process flow diagram (PFD) that allows individual components from fusel oil to be obtained without extraneous separating agents (not inherent in fusel oil). This condition is necessary to obtain products labeled as natural for further use in the food, perfume, cosmetic, and pharmaceutical industries. The distinctive feature of this work is that the target product is not only isoamyl alcohol but also all other alcohols present in the composition of fusel oil. To achieve this goal and create a mathematical model, the Aspen Plus V14 application, the Non-Random Two Liquid (NRTL) thermodynamic model, and the Vap-Liq/Liq-Liq phase equilibrium were used. Fusel oil separation was modeled using a continuous separation PFD to obtain ethanol, water, isoamyl alcohol, and raw propanol and butanol cuts. The Sorel and Barbet distillation technique was used to isolate ethanol. The isolation of isopropanol and 1-propanol, as well as isobutanol and 1-butanol, was modeled using the batch distillation method. The isolation of fusel oil components was based on their thermodynamic properties and the selection of appropriate techniques for their separation, such as extraction, distillation, pressure swing distillation, and decantation. The simulation of fusel oil separation PFD showed the possibility of obtaining the components of a complex mixture without separating agents, as discussed earlier. Ethanol corresponds to the quality of rectified ethyl alcohol, and 1-butanol and isoamyl alcohols to anhydrous alcohols, whereas isopropanol (which contains an admixture of ethanol), 1-propanol, and isobutanol are obtained as aqueous solutions of different concentrations of alcohols. However, due to a distillation boundary in the raw propanol and butanol cuts, these mixtures cannot be separated completely, which leads to the production of intermediate fractions. To eliminate intermediate fractions and obtain anhydrous isopropanol, 1-propanol, and isobutanol in the future, it is necessary to solve the dehydration problem of either fusel oil or the propanol–butanol mixture. [ABSTRACT FROM AUTHOR]

The measurability and predictability of the printing process are influenced by the impact of various coating methods. Besides enhancing and protecting the printed product, these methods can alter the colorimetric properties of spot colors across different wavelengths. Prediction models based on ink trapping formulas were analyzed, particularly those from Deshpande, Green, and Hoffstadt, designed to forecast colorimetric values in overprinted spot color scenarios. This study examined the influence of coating methods on the colorimetric properties of spot colors and evaluated the applicability of the prediction model for these conditions. Spectrophotometric and densitometric methods, combined with mathematical analysis, were used to quantify the degree of color change induced by different coatings. The findings clearly indicate the extent of colorimetric changes in spot colors resulting from various coating applications. They also highlight the potential, albeit limited, application of this model in predicting color changes for improved process repeatability and predictability. While the prediction method analyzed in this study proved inadequate for coating-over-spot-color scenarios, it remains useful for predicting colorimetric shifts in spot-on-spot-color overprinting. The model demonstrated that it is not entirely accurate, as some coatings show ∆E00 deviations of up to 10. To improve the model's applicability, a varnishing coefficient, V, should be introduced, which can reduce ∆E00 variation for each color and substrate. The research showed that a coefficient range from 0.8 to 1.2 yields acceptable results, bringing ∆E00 below 2, thus making the model suitable for coating processes with oil-based and UV coatings. [ABSTRACT FROM AUTHOR]

This study analyzes the influence of energy generated by emitters on the adhesive properties of varnish coatings in multilayer UV systems. The experimental material, in the form of a cell board finished with UV varnish products, was prepared on a prototype line under the conditions of Borne Furniture in Gorzów Wielkopolski. The roughness and wettability were measured using a OneAttension tensiometer integrated with a topographic module, taking into account the Wenzel coefficient. The adhesion of the examined systems was verified using the PositiTest AT-A automatic pull-off device. Energy consumption by the prototype production line was compared to the standard line, utilizing mercury emitters and mercury emitters with added gallium. Energy consumption was calculated for selected variants. The influence of the Wenzel coefficient on the wettability angle was observed. Significant differences between contact angles (CA and CAc) were noted for coatings formed with sealers (stages I and II). The largest discrepancies, reaching up to 30 degrees, were recorded at the lowest UVA and UVV doses of 26 mJ/cm2. In adhesion tests, values below 1 MPa were obtained. Insufficient energy doses in the curing process of UV systems led to delamination between the coatings. Five variants were selected where delamination within the substrate predominated (˃90% A) and were characterized by the lowest energy consumption in the processes. Topographic images helped identify the presence of various surface microstructures at different stages of the production cycle. The greatest energy savings, up to 50%, were achieved in stages III and IV of the technological process. [ABSTRACT FROM AUTHOR]

Introduction: This study investigated the effectiveness of titanium tetrafluoride (TiF4) varnish compared to sodium fluoride (NaF) varnish for preventing and remineralizing white spot lesions (WSLs) in individuals undergoing orthodontic treatment. Methods: This randomized, placebo-controlled, and double-blinded study was conducted with sixty-five adolescents who were selected based on caries activity and then randomized into three parallel groups: G1 (placebo varnish), G2 (5% NaF varnish), and G3 (4% TiF4 varnish). Volunteers received varnish application weekly for the first 4 weeks, after 6 (T1) and 12 (T2) months. The measured outcomes included prevention of new WSLs and reversal/progression of WSLs, assessed by Nyvad and International Caries Detection and Assessment System (ICDAS) indices, as well as quantitative light-induced fluorescence. χ2, ANOVA, and Kruskall-Wallis tests were applied. The level of significance was set at 0.05, and post hoc Bonferroni test for p values was performed to correct for multiple comparisons. Results: 1,274 teeth were included; 70.5% were Nyvad 0, and 29.5% were Nyvad 1, with no differences between the groups at baseline (T0). Regarding ICDAS, 70.5% were ICDAS 0, 21.6% were ICDAS 1, and 7.9% were ICDAS 2. G1 showed an increasing prevalence of WSLs at T1 and maintained stable at T2; G2 exhibited a decline at T2, while G3 experienced a decrease at T1 and T2 (p < 0.01). Incidence of WSLs at T2 was 10.2% (G1), 5.6% (G2), and 1.4% (G3). The percentage of teeth initially scored as Nyvad 0 that progressed to Nyvad 1 was 13%, 6.8%, and 1% for G1, G2, and G3, respectively. Conversely, the percentage of teeth initially scored as Nyvad 1 that regressed to Nyvad 0 or Nyvad 2 (T0–T2) was 14%, 49.3%, and 74.4%, respectively (p < 0.001). As for the ICDAS index, regression was observed in 6.5%, 17.8%, and 24%, while progression was observed in 14.9%, 7.7% and 0.9% for G1, G2, and G3, respectively (p < 0.001). Significant differences among the 3 groups for integrated fluorescence loss (mean ± SD, G1: −14.28 ± 9.47, G2: −11.10 ± 11.49, and G3: −6.77 ± 11.00) were found at T2 (p < 0.01). Conclusion: Both varnishes demonstrated the ability to prevent and remineralize WSLs. However, TiF4 varnish exhibited the most effective control over WSLs during the 12-month orthodontic treatment. Plain Language Summary: This study examined the effectiveness of two fluoride varnishes, titanium tetrafluoride (TiF4) and sodium fluoride (NaF), in preventing and remineralizing white spot lesions (WSLs) in individuals undergoing orthodontic treatment. We conducted a double-blinded, placebo-controlled trial with 65 adolescents randomized into three groups: placebo, NaF, and TiF4 varnish. These varnishes were applied weekly for the first month and then at 6 and 12 months. Our findings indicate that TiF4 varnish was the most effective in preventing new WSLs and promoting the remineralization of existing ones. The incidence of WSLs after 12 months was lowest in the TiF4 group (1.4%), followed by the NaF group (5.6%), and highest in the placebo group (10.2%). The placebo group exhibited a continuous increase in WSLs, while the NaF group showed improvement only at 12 months, and the TiF4 group demonstrated improvement at both 6 and 12 months. All groups experienced reduced visible plaque, with no significant differences between the groups. In terms of remineralization, TiF4 varnish demonstrated substantial improvements, with the best results observed at 12 months. In conclusion, TiF4 varnish proved most effective in preventing and remineralizing WSLs in a 12-month follow-up during orthodontic treatment. These results suggest that TiF4 varnish offers promise in managing WSLs in orthodontic patients. This study's findings have significant implications for the prevention and management of dental caries. [ABSTRACT FROM AUTHOR]

Quinones are one of the most commonly used drugs for cancer treatment. Combinations of quinoid compounds and other oxidation inducers with flaxseed oil (FO), which is rich in omega‐3 alpha‐linolenic acid, show promise for improving the efficacy of antitumor drugs. Effects of benzo‐, naphtho‐, and anthraquinones, as well as metronidazole and a number of nitro‐1,2,4‐triazoles on the oxidative stability of FO, were studied. To this end, kinetic curves were obtained showing the accumulation of hydroperoxides in FO during storage at 37°C with free access to atmospheric oxygen. The calculated oxidation induction period demonstrates that the majority of the tested quinones intensify the oxidation of FO. Pro‐oxidant activity is maximum for 1,4‐benzoquinone and significantly decreases (p < 0.05) when various substituents are introduced into its ring. A noticeable increase in the concentration of hydroperoxides and the rate of oxidation at the initial stage of the oxidation process is characteristic for 1,4‐benzoquinone and its derivatives. Additives of 1,4‐naphthoquinone and 2‐hydroxy‐1,4‐naphthoquinone (lawsone) do not affect the oxidative stability of FO, while 5‐hydroxy‐1,4‐naphthoquinone (juglone) and 4,6‐di‐tert‐butyl‐1,2‐benzoquinone effectively inhibit the oxidation of FO. The oxidation of FO lipids is accelerated by all investigated nitroazoles; however, 1‐methyl‐3,5‐dinitro‐1,2,4‐triazole has the highest pro‐oxidant activity. Practical Applications: The results of this study may be useful in the development of new methods of antitumor therapy using omega‐3 polyunsaturated substrates in combination with quinoid and nitrotriazole cytostatics. The data obtained can also be used in the development of oxidation‐stable foods based on flaxseed oil, as well as in the production of resins, drying oils, varnishes, paints, and other materials. [ABSTRACT FROM AUTHOR]

Surface engineering is one of the most extensive industries. Virtually all areas of the economy benefit from the achievements of surface engineering. Surface quality affects the quality of finished products as well as the quality of manufactured parts. It affects both functional qualities and esthetics. Surface quality affects the image and reputation of a brand. This is particularly true for cars and household appliances. Surface modification of products is also aimed at improving their functional and protective properties. This applies to surfaces for producing hydrophobic surfaces, anti-wear protection of friction pairs, corrosion protection, and others. Metal technologies and 3D printing benefit from surface technologies that improve their functionality and facilitate the operation of products. Surface engineering offers a range of different coating and layering methods from varnishing and painting to sophisticated nanometric coatings. This paper presents an overview of selected surface engineering issues pertaining to metal products, with a particular focus on surface modification of products manufactured by 3D printing technology. It evaluates the impact of the surface quality of products on their functional and performance qualities. [ABSTRACT FROM AUTHOR]

Esters are important chemicals used in fine and bulk chemical industry with numerous applications: solvents, paints, varnishes, dyes, and cosmetics. Ester formation is dominated mainly by Fischer esterification and transesterification. Fischer reaction is generally used for ester production, but in certain cases, transesterification can be used with advantage. It is useful when the acid is less soluble in the alcohol or in the solvent used, thus forming two layers. Water formation creates purification problems during esterification reactions due to azeotrope formation and transesterification can be useful in such cases. Commercially, cheaply available methyl and ethyl esters can be conveniently used as raw materials for value added ester production by transesterification. Transesterification is also useful when the parent acids are highly reactive and pose difficulty in separation. Transesterifications are slow reactions and a catalyst is used: acids and bases, ion exchange resins, zeolites, and clays. Homogeneous catalysts were used in the past which are now replaced by their heterogeneous counterparts. Heterogeneous catalysts offer added advantages like reusability, lesser corrosion, and ease of separation. Transesterification can be commercially used to produce a number of esters of industrial importance like acrylics and biodiesel. This review considers all these aspects in considerable detail. A large literature set was scanned and its judicious extract is presented. [ABSTRACT FROM AUTHOR]

Canvas paintings are layered structures composed of canvas support sized with animal glue, a preparatory layer of the ground, and paint and varnish layers on the top. Preventing or limiting humidity-induced stresses in these structures requires an understanding of the relevant processes and risks. A three-dimensional model of a canvas painting was used to analyse stresses and crack development in the two-layer structure comprised of a glue-sized canvas on a wooden stretcher with a layer of stiff chalk-glue ground representing a pictorial layer in historic canvas paintings. The model was subjected to a large relative humidity fall which induced shrinkage of the glue-sized canvas. The modelling revealed that when a stretcher with flexible wooden bars is considered, high tensile stresses arise in the ground layer at the corners of the painting, and cracks are formed in these areas in the direction perpendicular to the painting's diagonal. Ratios of critical distances between cracks to the ground layer thickness for which stresses in the midpoints between the cracks dropped to below the level inducing fracture in the material were estimated for various magnitudes of the relative humidity drop and thicknesses of the ground layer. Increasing ground layer thickness limits the hygric response of the sized canvas and makes the paintings less vulnerable to humidity variations. The ratio of stress along the diagonal calculated for painting with one crack to the solution without cracks was described by the double Lorentz function. A simple procedure of calculating stress variations along the diagonal—using the function—on a sequential addition of cracks was developed. Cracks in central parts of canvas painting were found to be induced by permanent cumulative drying shrinkage of the oil-based paints and grounds due to the evolution of the molecular composition of the oil binder. The outcome of the modelling indicated that the risk of cracking of the pictorial layers in canvas paintings due to drops in ambient relative humidity was small. [ABSTRACT FROM AUTHOR]

Graphene was mixed with varnishes at different ratios and applied by spraying method on different cross-sections of various wood materials, and their wear and adhesion performances were determined. Graphene (0.25%, 0.50%, 1%); varnishes (water-based and polyurethane varnish) and wood materials (beech (Fagus orientalis Lipsky), chestnut (Castanea sativa Miller), yellow pine (Pinus sylvestris L.), and spruce (Picea orientalis (L.) Link.)) were used. Adhesion and abrasion tests were performed. A total of 480 test specimens were prepared, 5 specimens for each wood type, cross-sectional direction, graphene ratio, and varnish type for adhesion and abrasion tests. The adhesion of the samples was determined by ASTM D 4541-09E1 pull-off test and abrasion resistance was determined in accordance with ASTM 4060-10. The data obtained were statistically analyzed and the significance values within and between groups were determined. As a result, abrasion resistance and adhesion increased in graphene 2 (0.50%) in both varnish types. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the effect of modifying some varnishes used in wood materials with different nanomaterials on the antimicrobial properties of wood surfaces. For this purpose, samples prepared from Scots pine (Pinus sylvestris L.) Oriental beech (Fagus orientalis Lipsky), and sessile oak (Quercus petraea Liebl.) were varnished with water-based and synthetic varnish with 0.1% and 0.3% nano boron and nano silver added according to ASTM D3023 (2017). Four different microorganisms (Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Staphylococcus epidermidis) were used to determine the antimicrobial effect on wood surfaces. Among the microorganisms, the highest growth was found in S. aureus and the lowest growth was found in S. epidermidis. In terms of antimicrobial activity, the lowest growth was found in samples with 0.1% nano boron synthetic varnish and highest growth was found in 0.1% water-based varnish. As a result, it is thought that the use of nano materials together with varnishes applied to the surface of wood materials in areas where antimicrobial properties are desired will be beneficial for human and environmental health. [ABSTRACT FROM AUTHOR]

This paper presents the archaeometric and chemometric authentication of a Renaissance-style oil painting on linen canvas, with plaster and barium sulphate-based primer preparation and bone glue as binder. By optical microscopy (OM), stereomicroscopy (SOM), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), a series of archaeometric characteristics were identified: the grain size of the chemical components of the paint layers, the 3D porosity distribution of the pigments, the degree of penetration between the paint layers and the varnish and between the varnish and the oxidatively anchored dirt, and the typology of the craquelure (craquelure network arrangement and morphology). By correlating the results obtained, it was possible to estimate the period of the painting as 1660 ± 3 years. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Interdental stripping, mechanical grinding of the proximal tooth surface, is a common practice to reduce mesiodistal diameter for orthodontic management of minor crowding and tooth shape or size disharmony. OBJECTIVES: The aim of the study was to evaluate the effectiveness of Duraphat and Clinpro varnishes in protecting stripped enamel and re-mineralizing initial enamel lesion. MATERIAL AND METHODS: Sixty-six stripped and sixty-six de-mineralized proximal surfaces of human premolars were covered with acid-resistant nail varnish, except for 3 × 4 mm enamel windows, and were assigned to group 1 (stripped enamel) and group 2 (initial enamel lesion), respectively. Each group was equally divided into 3 sub-groups (n = 22) according to varnish treatment for exposed windows: sub-group A (no varnish treatment, control), sub-group B (Duraphat varnish), and sub-group C (Clinpro varnish). Before each varnish application to its respective sub-groups, baseline Vickers micro-hardness test for each sub-group was done. All specimens were subjected to de-mineralizing solution for 10 days. Vickers micro-hardness for each sub-group was measured again at exposed enamel windows, and two specimens from each sub-group were examined under SEM. RESULTS: High statistically significant difference in micro-hardness was found between control sub-groups (228.2 ± 14.2 and 158.6 ± 13.3) and their respective sub-groups treated with either Duraphat (351.3 ± 15.2 and 281.5 ± 16.8) or Clinpro varnish (350.6 ± 15.4 and 280.4 ± 16.4), respectively (p = 0.000). No statistically significant difference was found in comparison between Duraphat and Clinpro sub-groups, or between treated subgroups and their respective baseline values (p > 0.05). Under SEM, protective layer of crystals was observed in treated sub-groups, while honeycomb-like de-mineralized enamel and variable sizes of porosities were seen in control subgroups. CONCLUSIONS: Both varnishes protect stripped enamel and re-mineralized initial enamel lesion. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate chitosan (CS)-based formulations loaded with 5% sodium fluoride (NaF) and/or 10% nanohydroxyapatite (nHA) to remineralize the demineralized primary tooth enamel surface. Ninety enamel blocks were demineralized and were divided into six groups (n = 15): (1) CS-based hydrogel, (2) CS-based hydrogel loaded with NaF, (3) CS-based hydrogel loaded with nHA, (4) CS-based hydrogel loaded with NaF and nHA, (5) 5% NaF varnish, and (6) negative control with no intervention. After intervention, the specimens were pH cycled by 2 h immersion in demineralizing solution and 22 h immersion in remineralizing solution for 8 days. The remineralization effects were evaluated by Vickers microhardness measurements and field emission scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (FESEM-EDS). The best mean ± SD percentage microhardness recovery in remineralized enamel (%REMH) was found in group 4 (56.90 ± 5.49). The %REMH of groups 2 (30.74 ± 3.51) and 5 (29.23 ± 5.65) were statistically the same (p = 0.943). FESEM images confirmed partial coverage of the porous demineralized enamel with a newly formed mineralized layer. Based on EDS findings, the Ca/P ratio values of the treated enamel surfaces with CS-based hydrogels ranged between 1.71 and 1.87, and the highest F content was noticed in group 2 (1.02 ± 0.03). Although, all tested CS-based hydrogels demonstrated the potential to repair demineralized enamel, nHA- and NaF-containing CS-based hydrogel showed the highest remineralization effect. We infer that this new hybrid hydrogel is a potentially useful dental material for tooth biomineralization. [ABSTRACT FROM AUTHOR]

Bis-(2-Chloroisopropyl) ether (BCIPE) was used as a solvent for fats, greases, paint, varnish removers, and in spotting and cleaning solutions. However, BCIPE has not been commercially manufactured or used for numerous years. In experimental animal studies, BCIPE is moderately toxic following acute oral, dermal, and inhalation routes of exposure. BCIPE is a severe eye irritant but not a dermal irritant or dermal sensitizer. BCIPE was not genotoxic or mutagenic in in vitro and in vivo assays; it was not toxic in a 3-generation reproductive dietary study in rats. Short-term, repeated inhalation and oral exposure in rats produced increased liver and kidney weights and congestion; dermal exposure in rabbits did not produce any observable adverse effects. BCIPE did not produce a statistically significant increase in tumors in two different 2-year dietary studies in mice and rats. In mice, technical grade BCIPE produced increased incidences of alveolar/bronchiolar adenomas in females, hepatocellular carcinomas in males, and a low incidence of forestomach hyperplasia (in both sexes at the high-dose). Further investigation with technical grade BCIPE concluded that these effects were species- and dose-specific with limited, if any, relevance to humans. The NOAEL of 400 ppm (15 mg/kg/day) from the 2-year dietary study in female rats was considered the point of departure for the health-based WEEL derivation. After adjustment for duration of exposure, interindividual variability, and intraindividual variability, an 8-h time-weighted average (TWA) WEEL value of 3 ppm (21 mg/m3) was derived. This exposure limit is expected to provide a significant margin of safety against any potential adverse health effects in workers. [ABSTRACT FROM AUTHOR]

This article presents the results of research work devoted to improving the characteristics of paint and varnish coatings based on aqueous dispersions of polyacrylates; it is proposed to modify them by introducing mineral raw materials as fillers and hydrated lime, with subsequent processing in a vortex layer apparatus. The introduction of activated diatomite does not cause the deterioration of covering power, adhesion or an increase in the porosity of the paint material. The modification of coatings contributes to an increase in their operational properties, which can be associated with a reduction in the free volume in the composite and the formation of polymer boundary layers with modified physical and chemical properties. The aim of this study is to obtain a water-dispersion paint and varnish composition containing modified diatomite on a polyacrylate basis and, subsequently, study its main physical and mechanical parameters. The work has been carried out by the following method: determination of porosity, adhesion, elasticity and covering power of the control composition; determination of porosity, adhesion, elasticity and covering power of the obtained composites using modified filler; investigation of the influence of radiation on the infrared spectrum of the paint coating surface using a FLIRB620 thermal imager. As a result of this research work, it was noticed that the modification of water dispersions with silica-activated diatomite helps to eliminate the main disadvantages of materials and coatings based on acrylate binders—low water resistance and low physical and mechanical characteristics. The introduction of modified diatomite into water-emulsion paint on an acrylate base does not lead to the deterioration of the main performance characteristics of paint coatings—porosity, adhesion, elasticity and covering. [ABSTRACT FROM AUTHOR]

This article concerns research into the influence of the energy dose distributed by UV lamps on selected parameters of varnish coatings formed during the varnishing process of lightweight cellular panels. The lightweight cellular board used in the study was made according to an innovative solution. The surface finishing of the boards was carried out using the roller method in combination with digital and analogue printing under industrial conditions. Contact angle measurements of the obtained varnish coatings were carried out, from which the surface free energy was calculated. In addition, interlayer adhesion was assessed by pull-off tests. Irrespective of the radiation dose, higher contact angle values (54.3–89.9°) were recorded for the last two applied layers (base coat 2 and base coat 3) than for the other coatings (39.6–64.1°). For all systems tested, the γsp component showed lower values (2.25–28.99 mJ/m2) than γsd (28.66–32.80 mJ/m2). The adhesion test results ranged from 0.5 to 0.9 MPa, although with varying types of delamination. Based on the test results, the most favourable variants from the furniture manufacturer's point of view were selected that provided the desired level of adhesion, in which cohesive damage located within the substrate (A) predominated. [ABSTRACT FROM AUTHOR]

ABSTRACT: Background: Dental caries remains a prevalent chronic condition affecting individuals worldwide, particularly children. Traditional fluoride varnishes have long been employed in caries prevention due to their ability to enhance enamel remineralization and reduce demineralization. Materials and Methods: A randomized controlled trial was conducted involving 120 participants aged 6–12 years with a high risk of dental caries. The participants were divided into two groups: one receiving nanosilver varnish and the other receiving traditional fluoride varnish. Each varnish was applied bi-weekly for six months. Salivary samples were collected at baseline, three months, and six months to measure bacterial counts, focusing on Streptococcus mutans. The data were analyzed using ANOVA to assess differences between the groups over time. Results: At baseline, both groups exhibited similar levels of Streptococcus mutans (P > 0.05). After three months, the nanosilver group showed a significant reduction in bacterial counts (mean reduction of 45%, P < 0.01), compared to a 30% reduction in the fluoride varnish group (P < 0.05). At six months, the nanosilver group maintained a 55% reduction, whereas the fluoride group showed a 40% reduction. The difference between the groups at six months was statistically significant (P < 0.01). Conclusion: Nanosilver varnish demonstrated superior antibacterial efficacy compared to traditional fluoride varnish in reducing Streptococcus mutans levels over six months. These findings suggest that nanosilver could serve as a valuable alternative or adjunct to fluoride varnish in caries prevention strategies. [ABSTRACT FROM AUTHOR]

In this study, solvent-based yacht varnish, stone varnish, and waxy varnish were applied in two coats using a brush, following industrial application standards, to the surfaces of the following tree species: black alder (Alnus glutinosa L. Gaertn.), curupay (Anadenanthera macrocarpa Benth.), iatandza (Albizia ferruginea), lemon (Citrus limon (L.) Burm.), loquat (Eriobotrya japonica L.), magnolia (Magnolia grandiflora L.), plane (Platanus orientalis L.), sucupira (Bowdichia nitida Benth.), and hornbeam (Carpinus betulus L.). Subsequently, the color parameters (b*, C*, L*, a*, ho, ∆E*, ∆H*, ∆b*, ∆C*, ∆a*, and ∆L*) of the varnish layers were compared with those of the untreated surfaces. The results of analysis of variance revealed significant differences in all color parameters. Decreases in L* values and increases in a* values were observed for all wood types when treated with three different varnishes. Additionally, in plane, black alder, and hornbeam wood, application of all varnishes resulted in increases in b* and C* values, with decreases in ho values. In sucupira wood, however, decreases were observed in b*, C*, and ho values with the application of all three varnishes. It was observed that a single type of varnish yielded different results on different wood types. This finding was attributed to the different types of resins present in the varnish types used in the study, which resulted in varying outcomes. [ABSTRACT FROM AUTHOR]

Fluoropolymers are attractive due to their high resistance to external influences. However, they are poorly compatible with other materials (for example, paints and varnishes for the purpose of their hydrophobization). Compatibility can be improved by introducing hydrophilic monomer units. A convenient method is copolymerization with functional monomers. In this work, the method of controlled radical polymerization was chosen to resolve this problem, which makes it possible to obtain compositionally homogeneous samples of copolymers with reproducible properties. The reversible addition-fragmentation chain transfer (RAFT) polymerization of 2,2,2,3,3,4,4,5,5-octafluoropentylacrylate (OFPA), 1,1,1,3,3,3-hexafluoroisopropylacrylate (HFIPA), and glycidyl methacrylate (GMA) in the presence of 2-cyano-2-propyldodecyltritiocarbonate was first investigated. It was shown that CPDT is effective to control molecular weight characteristics of POFPA and GMA in concentration not more than 0.01 mol·L−1 and of PHFIPA − 0.03 mol·L−1. Copolymerization of fluorinated monomers (OFPA, HFIPA) and functional monomers (GMA) in the presence of low molecular (CPDT) and polymeric chain transfer agent was investigated. Reactivity ratios of monomers were determined by Fineman–Ross and Kelen–Tudos methods. The use of polymeric RAFT agent leads to instance of preferential solvation effect and formation of copolymer with gradient microstructure at final conversion in case of OFPA-GMA copolymerization. Thus, RAFT copolymerization of fluoroacrylates and GMA leads to formation of copolymers with block, gradient, or statistical microstructure that depended on synthesis condition. Block copolymers have amphiphilic properties and are able to form monomolecular films at the air/water interface. Further research will be aimed at modifying the resulting polymers using the epoxy group of GMA. This will make it possible to combine in one material both the properties of a surfactant (to stabilize acrylic dispersions) and a water repellent for paints. [ABSTRACT FROM AUTHOR]

The paper deals with the issues and study of the properties of varnish-and-paint materials which are used to create protective-anddecorative coatings for joinery and building structures. The article provides an examination of comparative studies on the qualitative characteristics of alkyd varnish (PF-283) and drying linseed. Changes in the drying time of linseed oil and alkyd (pentaphthalic) varnish are determined depending on the material consumption and drying temperature. The studies have shown that the drying rate of films at the same material consumption at temperatures of 50 and 80°C is practically the same and ranges from 80 to 114 minutes. The article also presents the results of studies on the performance properties of finishing materials (coating thickness, water and heat resistance). It was found that alkyd varnish-and-paint materials form a coating of greater film thickness and hardness. In terms of water-resistance and heat-resistance, coatings based on drying oils have higher performance indicators. Recommendations are given for the use of alkyd and oil-based varnish-and-paint materials for finishing joinery and building structures made of oak wood which are used in wooden house construction. [ABSTRACT FROM AUTHOR]

Silsesquioxanes (SQs) are mostly used to provide high‐temperature electrical insulation of resins. Here, SQ is used to functionalize unsaturated polyester (UPE) varnish and investigate the effect of functionalization on the thermal and electrical properties of UPE varnishes. The solvent‐free varnish incorporates a reactive diluent to decrease viscosity and a catalyst to expedite hardening, eliminating the need for solvents. Vinyl toluene (VT) and 1,4‐butanediol dimethacrylate (BDDMA) serve as hardening agents, consistent with prior research. Various characterization tests, including Fourier transform infrared, thermogravimetric analyzer, assessment of thermal conductivity coefficient, and determination of electrical volume–surface resistance, are conducted to determine the physical, thermal, chemical, and electrical properties of the synthesized SQ‐functionalized UPE (UPES) varnishes. Results indicate that the UPES–BDDMA varnish demonstrates the highest thermal decomposition temperature at 438.0 °C, while the UPES–VT varnish exhibits the highest electrical volume resistance of 2.85 × 1015 Ω cm. Volatile organic compound levels in UPE coatings range between 4.9% and 5.10% reflecting the growing demand for eco‐friendly products. It is shown in this study that the use of BDDMA and VT reactive monomers in the synthesis of SQ‐functionalized UPE resin and the properties of the resulting varnishes, especially electrical insulation and thermal stability, are improved. [ABSTRACT FROM AUTHOR]

Purpose: The effects of different remineralization agents applied on enamel samples were evaluated by using surface and subsurface microhardness analysis. Methods: Sixty bovine incisor enamel samples were fabricated. After the initial microhardness values were measured, enamel samples are divided into 3 equal parts, and assigned as the treatment area (T), the adjacent area (A) and the control area (C) (covered with an acid-resistant varnish). Samples were subjected to pH cycle for 5-days, and then microhardness measurements were repeated. The specimens were randomly divided into 5 groups according to the fluoridereleasing materials applied, as follows: Group 1: BioMin F; Group 2: Colgate Triple Effect; Group 3: FCP COMPLEX; Group 4: Fluor Protector; Group 5: Artificial saliva (control). Following the applications, surface and subsurface measurements were performed. The data were analyzed by one-way analysis of variance (ANOVA) and post-hoc Tukey test. Results: BioMin F toothpaste provided the greatest increase in surface microhardness, followed by FCP COMPLEX, Colgate Triple Effect and Fluor Protector, respectively. Among the materials tested, BioMin F and Colgate toothpastes exhibited the highest increase in subsurface microhardness values, with FCP COMPLEX solution following closely in second place. Conclusions: BioMin F showed the best results in the surface microhardness assessment, while both toothpastes (BioMin F and Colgate) showed similarly positive results in the subsurface microhardness assessment. [ABSTRACT FROM AUTHOR]

The color-changing effect of tannin, which is a sustainable and environmentally friendly material used in wood preservation, was studied on varnished and un-varnished wood samples. For this purpose, walnut tannin was applied on samples prepared from Scots pine (Pinus sylvestris L.) and walnut (Juglans regia L.) wood in accordance with ISO 3129 (2019) standard with a brush, and then samples were coated with polyurethane varnish and water-based varnish according to ASTM D3023-98 (2017) principles. Color changes were determined according to ASTM D2244-21 (2021). The obtained data indicated that the highest value in the red color tone (a*) was observed in Scots pine+tannin+polyurethane varnish (PU) (14.4) and the lowest was in Scots pine+control+unvarnished (Uvr) (6.5). The highest value for the yellow color tone (b*) was observed in Scots pine+tannin+PU (34.1), the lowest was in walnut+control+Uvr (14.4), and the highest color lightness value (L*) was obtained in Scots pine+control+Uvr (77.0), and the lowest was obtained in walnut+tannin+PU (18.9). The tannin application, which darkened the wood surface, increased the a* and b* values in both wood types while decreasing the color lightness values 60% to 70%. Tannin application caused a noticeable decrease in total color changes in Scots pine. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate and compare the influence of two desensitizing agents in reducing dentine permeability. A 6-week study was conducted on 30 adult patients with hypersensitivity to two or more teeth . Patients were divided into two groups using a spilt-mouth study design; each patient received two different desensitizing agents (Gluma Desensitizer,Heraeus Germany, and Clinpro™ XT Varnish 3M ESPE, USA) in each side. The sensitivity was assessed at baseline, immediately after application, and after 1 week, 3 weeks, and 6 weeks. The tactile stimulus were applied with an explorer prob response using a visual analog scale and a standard cold air blast were used to compare the efficacy of desensitizing agents after a single application. The data were analysed using Wilcoxon test with a Bonferroni correction for non parametric data. Based on desansitizing agent, Gluma Desensitizer resulted in a significant reduction in pain scale compared to Clinpro™ XT Varnish using an air blast (P = 0.007) and a tactile test (P = 0.008) immediately post-treatment. All two desensitizing agents were effective in relieving dentin hypersensitivity (DH) up to 6 weeks, independent of their application procedures. There was, however, a significant reduction in mean sensitivity scores of teeth that had been treated with Gluma Desensitizer. [ABSTRACT FROM AUTHOR]

This study aimed to assess the effects of fluoridated varnishes supplemented with micrometric or nanosized sodium trimetaphosphate (TMPmicro or TMPnano, respectively) against enamel softening in an early erosive model in vitro. Bovine enamel blocks (with mean surface hardness [SH] between 330.0 and 380.0 kgf/mm2) were selected and randomly assigned according to their SH (n = 8) into the following groups: Placebo (no fluoride/TMP; negative control), 5% NaF (positive control), 5% NaF + 5%TMPmicro, 5% NaF + 2.5%TMPnano and 5% NaF + 5%TMPnano. Blocks received a single application of the varnishes and were immersed in artificial saliva (6 h). Thereafter, the varnishes were removed and the blocks were subjected to four individual erosive challenges (1 min, citric acid, 0.75%, pH = 3.5, under agitation); SH was determined after each challenge. Data were subjected to ANOVA and Student–Newman–Keuls' test (p < 0.05). Overall, the highest %SH loss was observed for the Placebo, followed by 5% NaF, 5% NaF + 5% TMPmicro, and both varnishes containing TMPnano, without significant differences between 2.5% and 5% TMPnano. It was concluded that TMP enhanced the effects of a 5% NaF varnish against enamel softening in an early erosive model in vitro, with an additional benefit from the use of nanoparticles over microparticles. [ABSTRACT FROM AUTHOR]

The process of dispersing solids in a liquid, as a combination of grinding different types of solid sediment and mixing crushed components, is one of the most relevant stages of the technological process for a wide range of applications in the chemical, food-technology, construction, mining, and pharmacology industries, as well as in the production of paints, varnishes, and other products. The design of the corresponding equipment requires improvement due to changes in the regulatory requirements of industrial end-users for finished products and the expansion of the areas of application of the corresponding devices. The development of criteria for choosing the type of design of continuous dispersants for specific types of production processes contributes to their successful design, taking into account the peculiarities of the movement of the working fluids, the physical and chemical properties of the working materials, consumable and grinding characteristics, production volumes, etc. Within the framework of a system-structural approach, an integrated classification system, which has found widespread use according to a number of traditionally identified characteristics, is illustrated on the example of several modern dispersant apparatuses. In particular, in this analysis, the following features of these devices are used: the type of basic physical law, the geometric location of the working chamber, the volumetric characteristics of the grinding basket; as well as the methods for setting the grinding bodies in motion; the separation methods; the placement of the grinding chamber; etc. The analysis of the fundamental differences for various types of devices with freely moving working fluids allows us to identify their advantages and disadvantages and to highlight directions for improving the designs of dispersing equipment depending on the regulatory dispersion of the finished product on the example of grinding pigments for paint and varnish production. [ABSTRACT FROM AUTHOR]

[Display omitted] Over the last few decades, significant research efforts have been devoted to developing new cleaning systems aimed at preserving cultural heritage. One of the main objectives is to selectively remove aged or undesirable coatings from painted surfaces while preventing the cleaning solvent from permeating and engaging with the pictorial layers. In this work, we propose the use of electrospun polyamide 6,6 nonwovens in conjunction with a green solvent (dimethyl carbonate). By adjusting the electrospinning parameters, we produced three distinct nonwovens with varying average fiber diameters, ranging from 0.4 μm to 2 μm. These samples were characterized and tested for their efficacy in removing dammar varnish from painted surfaces. In particular, the cleaning process was monitored using macroscale PL (photoluminescence) imaging in real-time, while post-application examination of the mats was performed through scanning electron microscopy. The solvent evaporation rate from the different nonwovens was evaluated using gravimetric analysis and Proton Transfer Reaction- Time-of-Flight. It was observed that the application of the nonwovens with small or intermediate pore sizes for the removal of the terpenic varnish resulted in the swollen resin being absorbed into the mats, showcasing a peel-off effect. Thus, this protocol eliminates the need for further potentially detrimental removal procedures involving cotton swabs. The experimental data suggests that the peel-off effect relates to the microporosity of the mats, which enhances the capillary rise of the swollen varnish. Furthermore, the application of these systems to historical paintings underwent preliminary validation using a real painting from the 20th century. [ABSTRACT FROM AUTHOR]

The article focuses on Valentina Fetisova's transition from ballet to painting intricate designs on labradorite gemstones. Topics include her early career in ballet, her development of a unique painting technique utilizing the gem's natural labradorescence, and her current work showcasing various scenes such as wildlife and sci-fi themes.

Investigators seeking to solve the mystery of rock varnish formation have yet to embrace hypothesis testing. Thus, this paper presents nine tests that assess the validity of the eight hypotheses proposed over the last four decades to explain varnish formation. An almost singular focus on manganese (Mn)-enrichment by many in varnish research may have led to six of the eight hypotheses failing to explain iron (Fe)-enrichment, as well as why clay minerals dominate the composition of rock varnish. Many varnish researchers displayed a sampling bias by collecting samples only from hot and dry deserts; thus, it should be of no surprise that four hypotheses failed a test of explaining varnishes in different climates; five hypotheses failed to explain varnishes in subsurface locations; and seven hypotheses failed to explain differences in varnish growth rates in hot deserts versus wetter locations. In the end, seven of eight proposed hypotheses to explain varnish formation failed more than five tests, any one of which would falsify the hypothesis. Only one hypothesis "passed" all nine tests. [ABSTRACT FROM AUTHOR]

On the occasion of the reopening of the Dobrée Museum (Nantes, France), two statuettes of Egyptian origin, representing Harpocrate and Isis, were studied to shed light on the presence of the blue-green efflorescence on their surface. The efflorescence on the Harpocrate statuette was identified as being chalconatronite, while that which was present on the Isis statuette corresponded to sodium copper formate/acetate, probably due to the evolution of chalconatronite in an environment containing VOCs. The efflorescence appeared to be sensitive to the cyclic variation in relative humidity whereas it seemed stable. An experimental curative treatment to halt the reappearance was carried out. A series of pure water baths extracted a significant quantity of sodium. The treatment appeared effective and reduced the risk of a recrudescence of the efflorescence for both statuettes. However, when the efflorescence was dissolved on the Isis statuette, other compounds appeared to react with water, leading to acidification and a potential reaction with the lead in the alloy. A layer of lead carbonate/acetate on the surface appeared. The objects were then dried and protected with a highly concentrated acrylic varnish. They are currently being monitored to identify any new efflorescence that may appear during display. [ABSTRACT FROM AUTHOR]

Objective: Colour stability is important in the long-term aesthetic success of restorative materials and is affected by both internal and external factors. Internal discolourations are due to the properties of the restorative materials. External discolourations can be associated with frequent consumption of food and beverages and the use of suspensions or syrups containing colourants/additives. Fluoride varnish application has an important place in preventive dentistry. The purpose of the research was to examine the protective effect of fluoride varnish application on the colour change on polyacid-modified composite resin restorative materials caused by the use of various paediatric drugs. Methods: Two hundred ten discs were prepared from polyacid-modified composite resin material and divided into two groups: flouride varnish was applied to one group and flouride varnish was not applied to the other group. The groups were further divided into seven subgroups and the samples were kept in artificial saliva, amoxicillin + clavulanic acid, cefuroxime axetil, clarithromycin, paracetamol, ibuprofen, and iron supplement drug solutions. The colour change values of the discs were measured using a spectrophotometer device before immersion in the drug solutions and on the 7th, 14th, 21st, and 28th days after the immersion. The obtained data were calculated and statistically evaluated using IBM SPSS V23 software. Results: It was found that the application of fluoride varnish in the iron supplement drug group prevented the colour change of the polyacid-modified composite resins for 28 days. In the amoxicillin + clavulanic acid, cefuroxime axetil, and paracetamol groups, the fluoride varnish did not prevent colour change in the polyacid-modified composite resin restorative materials at the end of the 14th day. Conclusion: It is thought that fluoride varnish application may be beneficial as a preservative in the colour change of polyacid-modified composite resins due to the use of various paediatric drugs, and this protective feature may be effective for a specific period of time. [ABSTRACT FROM AUTHOR]

aimani, Sulaymaniyah, Iraq Correspondence: Sonya Jamal Hamalaw, Sulaimaniyah, 46001, Iraq, Tel +9647705049108, Email [email protected] Purpose: Antibacterial and antibiofilm properties of magnesium oxide nanoparticles (MgONPs) mixture assessed against Streptococcus mutans (S. mutans), in addition to examining MgONPs varnish impact on the preservation of the tooth color and inhibition of methylene blue diffusion to the enamel. Methods: MgONPs mixture was prepared in deionized water (DW), absolute ethanol (E), and rosin with ethanol (RE), named varnish. The antibacterial and antibiofilm capacities of MgONPs mixtures were tested by agar well diffusion, colony-forming unit (CFU), and biofilm inhibition microtiter methods in triplicate and compared to sodium fluoride varnish (NaF) and chlorhexidine mouthwash (ChX). A spectrophotometer was used to record basic tooth color. The artificial demineralization was initiated for 96 h. Then, experimental materials were applied to the corresponding group, and 10-day pH cycles proceeded. Then, the color was recorded in the same ambient environment. The methylene blue diffusion was evaluated by staining the samples for 24 h. After that, the diffusion test was calculated by a digital camera attached to the stereomicroscope. Results: The agar well diffusion test expressed a significant inhibition zone with all MgONPs mixtures (p = 0.000), and maximum inhibition zone diameter associated with MgONPs-RE. The same finding was observed in the CFU test. Additionally, 2.5%, 5%, and 10% MgONPs-RE varnish showed strong biofilm inhibition capacity (p = 0.039) compared to NaF and ChX groups that inhibit biofilm formation moderately (p = 0.003). The study shows that the 5% MgONPs-RE varnish maintains basic tooth color with minimal methylene blue diffusion compared to NaF varnish (p = 0.00). Conclusion: Evaluating MgONPs as a mixture revealed antibacterial and antibiofilm capacity against S. mutans with a higher effect of MgONPs-RE varnish. Also, examining the topical effect of MgONPs-RE varnish on the preservation of the tooth color after pH cycle challenges and methylene blue diffusion to enamel confirmed the high performance of MgONPs-RE varnish at 5%. [ABSTRACT FROM AUTHOR]