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Purpose: To compare the bond strengths of three types of permanent silicone and acrylic resin soft liners to the denture-base acrylic resin by employing both synchronous and asynchronous processing methods and different surface treatments.Materials and Methods: A total of 198 cylindrical samples were fabricated from denture-base acrylic resin and a 3-mm soft liner. Surface treatments of the samples were classified into five groups (n = 33 each): no treatment (control); erbium:yttrium-aluminum-garnet (Er:YAG) laser; grit-blasting with 150-μm particles; monomer application; and phosphoric acid application. In addition, synchronous processing (n = 33) of the acrylic resin denture base and the soft liner was performed. Each group was divided into three subgroups (n = 11 each) based on the type of soft liner: Group M (Molloplast-B [silicone]), Group P (PermaFlex [silicone]), and Group A (AcroSoft [acrylic resin]). The samples were processed and thermocycled for 5,000 cycles between 5°C and 55°C, and the tensile strength test was then performed. The maximum tensile strength to failure and the type of failure were recorded, and Dunn statistical analysis and Kruskal-Wallis tests were used for comparison of the groups. The surface treatments were assessed using scanning electron microscopy.Results: Irrespective of the method of processing or surface treatment, Group A had a significantly higher bond strength (8.1 ± 1.1 MPa) than the other two soft liners (Group M: 1.9 ± 0.3 MPa, Group P: 1.1 ± 0.2 MPa; P < .001). Moreover, in Group A, the synchronous processing method produced a significantly higher tensile strength (P < .001), while in Group P (P = .112) and Group M (P = .993), synchronous processing had no significant effect on bond strength. Bond strength after surface treatment in Group M was lowest after grit blasting (0.7 ± 0.2 MPa) and highest after monomer application (3.1 ± 0.5 MPa) (P < .001). The same was observed for Group P in grit blasting (0.5 ± 0.2 MPa) and monomer application (2.1 ± 0.3 MPa) (P < .001). For Group A, grit blasting (4.8 ± 0.7 MPa) was also the lowest and the monomer application (8.1 ± 0.8 MPa) the highest ± (P < .001), while the bond strength resulting from the synchronous processing method was higher than that of the other methods (14.7 ± 2.1 MPa).Conclusion: Within the limitations of this in vitro study, the acrylic resin soft liner showed the best bond strength. In all types of soft liners, surface treatment with the monomer resulted in higher bond strengths. Synchronous processing exhibited a significantly higher bond strength for the acrylic resin soft liner, but not for the silicone soft liners. [ABSTRACT FROM AUTHOR]

Purpose: To test a novel implant metal-acrylic prosthesis design in comparison to a conventional prosthesis design through simulation of cyclic masticatory loading. The novel design involved digital designing and fabrication of the framework and the matched veneering acrylic resin material. Materials and Methods: Ten prostheses were fabricated for each group. All the prostheses exhibited a similar external design on two implants with a distal cantilever. The conventional group comprised a milled metal framework with mechanically retained acrylic denture teeth via vertical pins. The digital prosthesis group incorporated an inverted T-shape bar and a monolithic milled acrylic resin veneer. The resin veneer was subsequently adhesively attached on the bar. All prostheses were thermally aged and subjected to laboratory cyclic loading at the cantilever region. The load-to-failure and the number of cycles until failure were collected. Furthermore, failed specimens were analyzed to determine the mode of failure. Results: The digital prostheses failed at significantly greater load-to-failure (1,570.0 N ± 116.0 N) and number of cycles (124,857 ± 21,608) than the conventional prostheses (load-to-failure = 1,015.0 N ± 47.4 N; number of cycles = 28,452 ± 6,559). The conventional prostheses failed by fracturing of the acrylic teeth and veneering material that led to exposure of the metal framework. Half of the digital prostheses failed by superficial chipping of the veneering material, while the other half failed by the deformation and fracture of screws. Conclusion: Within the limitations of this study, the digital prostheses with the novel design and monolithic veneering material showed significantly higher strength compared with the conventional prostheses. The mode of acrylic failure of the digital prostheses was more favorable. [ABSTRACT FROM AUTHOR]

Purpose: Three commercial restorative glass-ionomer cements (GICs) were modified with 5% and 10 wt/wt% nanodiamond (ND) particles incorporated into the powder of the GICs. The aim of the study was to assess the percentage of surface fluoride increase on different materials, following 2% neutral sodium fluoride gel application (2% NSF). Materials and Methods: The commercial GICs were: FN, Fuji IX GP (GC); KU, Ketac Universal (3M Oral Care); and RSC: Riva Self Cure (SDI). Grade 1 (Plasmachem) nanodiamond was used. Six specimens of each material were prepared using precise powder:liquid ratios. After a 10-min setting time, the GICs were polished. The specimens were randomly divided into two groups: control (group A) and test (group B). The samples were blot dried and group B received the 2% NSF gel for 2 min. The excess was wiped off with gauze and both groups were analyzed with SEM-EDS. Results: Data analysis revealed that all the GICs and their respective ND modifications had a statistically significant surface fluoride percentage increase (p < 0.0001) on the GICs in group B. The addition of ND10% w/w to FN (p < 0.001) and RSC (p = 0.029) resulted in statistically significant increase of surface fluoride percentage. KU remained consistent with no statistically significant increase noted between ND-modified KU and KU in group A or B. Conclusion: The ability of GICs to absorb the 2% NSF gel immediately after finishing of the restoration statistically significantly increases the fluoride percentage of the surface layer. [ABSTRACT FROM AUTHOR]

Aim: This study aimed to evaluate the biocompatibility, flexural strength, and surface roughness of polymethyl methacrylate (PMMA) containing Copper Oxide Nanoparticles (CuO NPs) at different concentrations. Methods: 25 heat-polymerized PMMA wax patterns fabricated in 5 groups containing 0.5, 5, 50, and 500 μg/ml CuO NPs and nanoparticle (NP)-free PMMA discs were prepared. 5 growth mediums (DMEM with 10% FBS and 1% penicillin-streptomycin) without disks were also incubated similarly to serve as the control groups. The cytotoxicity of the discs was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay on cultured Human Gingival Fibroblasts. The number of 1.3 × 104 cells were seeded in each well of 96-well plates (5 wells for the extract of each specimen). Days 1, 3, 5, and 7 were the intervals that the culture media were in direct contact with the PMMA discs for either 24 or 72 h. After that, a total of 40 specimens with 65 × 10 × 2.5 mm dimensions were prepared in five groups (n = 8). The specimens were subjected to a rugosimeter for the evaluation of surface roughness. The flexural strength test was performed using a universal testing machine. Microscopic evaluation was performed for the dispersion of the NPs. Non-parametric Kruskal-Wallis test and parametric one-way ANOVA test were used for data analysis. Results: The samples containing 500 μg/ml NPs showed the lowest percentage of cell viability at all incubation periods, while the highest cell viability was observed in NP-free PMMA 24 h after the seventh day of incubation. NPs at 50 and 500 μg/ml concentrations showed strongly significant differences in cytotoxicity compared to the 0 concentration and the control group (p

Background: The accuracy of intraoral scanning plays a crucial role in the workflow of computer-assisted design/computer-assisted manufacturing. However, data regarding scanning accuracy for inlay preparation designs are lacking. The purpose of this in vitro study was to evaluate the influence of the depth of the occlusal cavity and width of the gingival floor of the proximal box on the trueness and precision of intraoral scans for inlay restoration. Methods: Artificial teeth were used in this study. Four types of preparations for mesio-occlusal inlay were performed on each #36 artificial tooth depending on two different depths of the occlusal cavity (1 mm and 2 mm) and widths of the gingival floor of the proximal box (1.5 mm and 2.5 mm). Artificial teeth were scanned 10 times each with Cerec Primescan AC, and another scan was performed subsequently with a laboratory scanner as a reference (n = 10). Standard tessellation language files were analyzed using a three-dimensional analysis software program. Experimental data were analyzed using two-way analysis of variance and the Bonferroni multiple comparison test. Results: The narrow shallow group had significantly higher deviation values for trueness than the wide deep group (p < 0.05). The wide deep group had the lowest average deviation value for trueness and there was no significant difference between the narrow deep and wide shallow groups (p > 0.05). For the mean maximum positive deviation, the wide groups had significantly lower values than the narrow groups (p < 0.05). Trueness was affected by both the width and depth(p < 0.05), whereas the mean maximum positive deviation was affected by the width (p < 0.05). The mean maximum negative deviation was affected by all three factors (p < 0.05). Precision was affected by the depth and the interaction between the depth of the occlusal cavity and width of the gingival floor (p < 0.05). Conclusions: The design of different inlay cavity configurations affected the accuracy of the digital intraoral scanner. The highest average deviation for trueness was observed in the narrow shallow group and the lowest in the wide deep group. With regard to precision, the narrow shallow group showed the lowest average deviation, and the narrow deep group showed highest value. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the effect of applying short E-glass fiber (SEG) and ultrahigh molecular weight polyethylene (UWPE) filler on the shear bond strength between the repaired surface of the rapid heat-cured and the reinforced autopolymerized acrylic resin. Fifty-six circular (15 × 3.3 mm2) rapid heat-cured resins were made and assigned equally to seven different groups. These were later bonded to fifty-six circular-reinforced autopolymerized acrylic resin specimens. Every test group included a control group, along with applying 1% and 2% SEG, 0.5% SEG/UWPE, 1% SEG/UWPE, and 1% and 2% UWPE. The universal testing machine was utilized to conduct the shear bond strength test. The repaired surface of these samples was assessed. Besides, the mode of failure was visualized under stereo microscope. The shear bond strength of all experimental groups was significantly higher than that of the control group. Group 3 with the addition of 1% SEG demonstrated the highest significance (12.86 MPa). The mode of failure for most of specimens was a mixed failure. Thus, it is indicated that enhancing the resin with 1% short E-glass fiber significantly improves the shear bond strength between repaired surface of the rapid heat-cured acrylic resin denture base and the reinforced autopolymerized acrylic resin. [ABSTRACT FROM AUTHOR]

This study evaluated the potential of Ziziphus mauritiana Lam (Z. mauritiana Lam) ethanol extract improves thermal stability and strength to prevent the growth and biofilm formation of C. albicans. The assessment of heat release (thermal equilibrium) of acrylic resin using Differential scanning calorimetry, the strength of acrylic resin with the universal testing machine, growth assessment of C. albicans by spectrophotometry, and biofilm assay with crystal violet and visual images used to a microscope. Z. mauritiana Lam 12.5% provides better thermal stability with a cooling peak enthalpy of -223.27 cal/g. In addition, concentrations of 6.25% and 3.125% at 48 hours had a better ability to increase the strength of acrylic resin (p>0.05). Z. mauritiana Lam at all concentrations and incubation of 24 and 48 hours were similar in decreasing the growth of C. albicans (0.06-0.08 or equivalent to <300 CFU/mL). Concentrations of 3.125% and 6.25% had a better ability to inhibit the biofilm formation of C. albicans on the acrylic resin surface. There was no significant difference between the inhibition of growth and biofilm formation on acrylic resin based on incubation time and concentration (p>0.05). The Z. mauritiana Lam increased heat release (thermal stability) in acrylic resin, which caused an increase in transverse strength. At the same time, it reduces the growth and biofilm formation of C. albicans on the acrylic resin surface. [ABSTRACT FROM AUTHOR]

Introduction: Silicon Soft Denture Liner (SDL) is often used along with heat polymerization acrylic resin (PMMA) as an obturator material because it can cover the undercut area in a broad defect for long term and painlessly. Despite that, silicon SDL and PMMA have different molecular structures so that they have a low bond strength. Long-term use can also affect the bond strength, so there is a need to increase the bond strength between PMMA and SDL. A method to increase the bond strength is surface treatment. This study is conducted to determine the effect of surface treatment and thermocycling on the bond strength of PMMA and Silicon SDL. Methods: The study used 40 samples (8 groups) divided into 4 groups based on the surface treatments, namely no surface treatment, sandblast, adhesive primer and combination, and further divided into two groups of thermocycling and without thermocycling treatment. The bond strength between PMMA and SDL was tested with tensile test by using Universal Testing Machine (UTM). Results: One-way ANOVA analysis showed there were significant differences of the bond strength among all groups (p <0.05) where the adhesive primer showed the highest value in all treatment groups. Conclusion: There is an effect of surface treatment and thermocycling on the bond strength between the PMMA and SDL, where the adhesive primer as a surface treatment material shows the highest bond strength of all. [ABSTRACT FROM AUTHOR]

Durability is a key factor to determine the service life of organic coating. The addition of nanomaterials can improve the mechanical properties and compactness of the organic coatings. As a kind of nanomaterial, g-C3N4 has lamellar structure and can be excited by visible light. At the same time, its cost is low. So it can be selected as a filler to prepare organic coating. The lamellar structure of g-C3N4 is favorable for its dispersion in organic coatings. Stearic acid is an environmentally friendly material with low surface energy. It can improve the hydrophobicity of the coating. In this research, porous g-C3N4 nanosheets were used as filler and stearic acid was used as surface modifier to prepare waterborne acrylic resin-based organic composite coating. The chemical reagent durability, electrochemical durability and mechanical properties of the composite coating were tested. At the same time, the photocatalytic degradation performance of the coating surface was also tested. The results showed that g-C3N4 as filler and stearic acid could effectively improve the durability of the waterborne acrylic resin coating. Meanwhile, the coating surface has obvious visible light-activated photocatalytic performance due to the addition of g-C3N4. [ABSTRACT FROM AUTHOR]

• The state of art of research in protective coatings for metallic cultural heritage has been reviewed. • A wide selection of representative papers testing protective coatings has been summarized. • Data on substrate, application, weathering and examination procedures is presented. • This review is intended as a starting point for future studies and developments in metal protection. The study and development of protective coatings for metallic heritage is a topic of continuous research, with the main objective of ensuring the protection of the object for as long as possible. The limitations imposed by conservation and restoration criteria, together with the diversity of factors involved, make metal protection an unresolved subject. In addition to the nature of the protective coating, different factors can influence its effectiveness, which may mean that one type of protection performs well in a certain environment or on one type of metal and not on another. Therefore, the main objective of this work is to provide a comprehensive review of the coatings used in the conservation of metallic heritage from the last decades to the present day. Studies carried out on coatings of the different families according to their nature/composition (waxes, acrylic resins, nitrocellulose lacquers, fluoropolymers, carboxylates, organosilanes compounds and other coatings) have been reviewed, considering the substrate, application, weathering and examination. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the effect of acid erosion on different physical properties of resin composite with S-PRG (surface pre-reacted glass) fillers, by conducting simulations of intrinsic and extrinsic sources. Materials and methods: Cylindrical samples (Ø6 vs. 2 mm) of a conventional nanohybrid resin composite (Forma, Ultradent) and of a nanohybrid resin composite with S-PRG filler (Beautifil II, Shofu) were exposed to erosive cycling (5 days), based on (n=12) remineralizing solution (control); 0.3% citric acid (pH=2.6); or 0.01 M hydrochloric acid (pH=2). Roughness (Ra), microhardness (KHN), and color (CIEL*a*b*, CIEDE2000, and Vita scale (SGU)) factors were analyzed at the initial and final time points, and the general color changes (ΔEab, ΔE00, ΔSGU) were calculated. Final images were obtained using scanning electron microscopy (SEM). The data were evaluated by generalized models, Mann-Whitney, Wilcoxon, Kruskal-Wallis, and Dunn tests (α=0.05). Results: Regarding KHN, there was no difference between the groups or the time periods (p = 0.74). As for Ra, there was a significant increase in the Ra of both composites after cycling with hydrochloric acid, but only the resin composite with S-PRG filler showed a change in Ra after cycling with citric acid (p = 0.003). After cycling with citric and hydrochloric acid, the highest Ra values were found for the resin composite with S-PRG filler (p < 0.0001), corroborating the result of images (SEM) indicating loss of filler and porosities in this material. The resin composite with S-PRG filler showed higher ΔEab and ΔE00, in addition to more negative ΔSGU values and lower L* values after exposure to both acids, compared to the control (p < 0.05). Conclusion: The acidic conditions altered the roughness and color stability of the materials tested, pointing out that the resin composite containing S-PRG filler showed greater degradation of its physical properties than the conventional resin composite. Clinical relevance: Bioactive materials are relevant, considering that their properties interact with dental hard tissues; however, the S-PRG-based resin composite showed greater degradation under acidic conditions than the conventional resin composite. [ABSTRACT FROM AUTHOR]

Purpose: There are three double bonds in the chemical structure of diallyl maleate. The purpose of this study is that the acrylate is modified with diallyl maleic anhydride to make the propionate resin present a spatial network structure, thereby improving the performance of the acrylate resin. Design/methodology/approach: Methyl methacrylate (MMA) and butyl acrylate(BA) were used as were used as main monomers. Diallyl maleate (DAM) was used as crosslinking monomer and dodecafluoroheptyl methacrylate (DFMA) was used as fluoromonomer. Potassium persulfate (KPS) was used as thermal decomposition initiator, sodium lauryl sulfate (AS) and sodium dodecyl sulfonate (SDS) were used as anionic emulsifiers, and EFS-470 (Alkyl alcohol polyether type nonionic emulsifier) was a non-ionic emulsifier. Findings: Through optimizing the reaction conditions, the uniform and stable latex is obtained. The polymer of structure was characterized by Fourier transform infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) and contact angle (CA) were tested on latex films. The particle size and distribution range of emulsion were tested with nano particle size analyzer. Originality/value: The experimental results showed that the thermal decomposition temperature of the acrylic coating film increased by 20.56°C after modification. In addition, the effect of cross-linking density on the water contact angle of the fluorocarbon groups in DFMA when they migrate to the surface of the latex film during drying has been explored. The experimental results show that a higher degree of cross-linking will hinder the migration of fluorocarbon groups to the surface of the resin film. [ABSTRACT FROM AUTHOR]

A unique UV-Curing method is provided for decontamination of radioisotopes on the surfaces which has radiation dealing facilities. In this method acrylic UV-Curing resin was poured on a contaminated simulated surface followed by UV irradiation. The resin interacted with the contaminated surface and after polymerization, the solidified resin was then stripped off, leaving behind a clean surface. The present study is the proof-of-concept of a novel application of acrylic resin UV-Curing methodology for Radioactive surface contamination removal to create a economical clean, effective and safe environment with minimal waste generation post processing ready for environment friendly incineration. [ABSTRACT FROM AUTHOR]

The organic fluorine modified/containing cationic acrylic resin is prepared via solution polymerization technique using hexafluorobutyl methacrylate (HFMA) along with butyl acrylate (BA), methyl methacrylate (MMA), styrene (St), dimethylaminoethyl methacrylate (DMAEMA) and hydroxy propyl methacrylate (HPMA) as the comonomers, proprylene glycol monomethyl ether (PGME) as the solvent, and 2, 2-Azo-bis-iso-butyronitrile (AIBN) as the initiator. The synthesized resin in which fluorine atom is introduced into the polymer chains. The cathodic electrodeposition (CED) coatings were prepared by mixing the synthesized resin and blocked isocyanate. The influence of the amount of organic fluorine on the resin and the resultant CED coatings is investigated in detail. In view of the appearance and hydrophobicity of the film, the optimum amount of organic fluorine is obtained, which is 12.0%. The hydrophobicity and the acid and alkaline resistance properties of the coating film are improved when the organic fluorine monomer is introduced into the resin. [ABSTRACT FROM AUTHOR]

Purpose: We aimed to evaluate the effectiveness of photoreactive 2-methacryloyloxyethyl phosphorylcholine (MPC) in inhibiting Candida albicans biofilm formation on polymethyl methacrylate (PMMA) and assess its mechanism and need for re-application by evaluating its interaction with salivary mucin and durability during temperature changes. Methods: PMMA discs were used as specimens. The MPC coating was applied using the spray and cure technique for the treatment groups, whereas no coating was applied to the control. The MPC treatment (MT) groups were further differentiated based on the number of thermal cycles involved (0, 1000, 2500, and 5000). The optical density was measured to assess mucin adsorption (MA). Contact angle (CA) was calculated to evaluate surface hydrophilicity. The presence of MPC components on the PMMA surface was assessed using X-ray photoelectron spectroscopy (XPS). C. albicans biofilms were evaluated qualitatively (scanning electron microscope images) and quantitatively (colony-forming units (CFUs)). Statistical analysis was conducted using two-way analysis of variance and Tukey's multiple comparison test. Results: MA rate and CA increased significantly in the MT groups, which exhibited significantly fewer CFUs and thinner biofilms than those of the control group. Based on the XPS, MA, and CFU evaluations, the durability and efficacy of the MPC coating were considered stable up to 2500 thermal cycles. Additionally, a significant interaction was observed between mucin concentration and MPC efficacy. Conclusions: The photoreactive MPC coating, which was resistant to temperature changes for approximately 3 months, effectively prevented C. albicans biofilm formation by modifying surface hydrophilicity and increasing mucin adsorption. [ABSTRACT FROM AUTHOR]

Objectives Fixed orthodontic retainers are pivotal in determining the success of treatment outcomes. However, the bonding materials utilized in their construction are not completely inert. These materials may release bisphenol A (BPA), a compound associated with various health risks. This study aimed to evaluate the cytotoxicity of potential bonding agents used in fixed orthodontic retainers. Methods In this experimental study, human gingival fibroblasts were cultured and subjected to various dental materials. These materials included acrylic resin (representing removable retainers), Transbond LR, and Enlight LV (which are common adhesives for fixed retainers), as well as Gradia Direct, Direct Flo, and Herculite XRV (commonly used in restorative composites). A control group was also exposed to normal saline. Discs measuring 0.5×1×1 mm were prepared from these materials. The viability of the fibroblasts was assessed using the MTT assay, and a statistical analysis (one-way analysis of variance) was conducted to compare the groups at a significance level of 0.05. Results The results of statistical analysis indicated no significant difference between the groups in terms of cytotoxicity for human gingival fibroblasts (p= 0.71). Conclusion None of the tested materials negatively impacted the viability of human gingival fibroblasts. These results provide valuable clinical insights, reassuring orthodontic practitioners about the safety profile of these commonly used materials in the context of fixed orthodontic retention and restorative procedures. [ABSTRACT FROM AUTHOR]

Introduction: One of the most popular restorative materials today is resin‑based composite. Volumetric shrinkage is brought on by polymerization, which can cause contraction stress, microleakage, and adhesion failure. Adhesive restorations have several benefits, including the ability to preserve more healthy tissue and “reinforce” the remaining tooth structure. These benefits go beyond just being attractive. Materials andMethods: Eighty extracted human maxillary premolars were entrenched in a self‑cured acrylic resin in a rubber mold cylinder(2.5 cm width‑3 cm height). These were arbitrarily divided into 5 groups: 2 control groups(positive control group and negative control group)(n = 10) and 3 experimental(n = 20) groups(microhybrid composite, nanocomposite, and Giomer). The mesio‑occluso‑distal (MOD) cavities were prepared in 70 samples. After MOD cavities preparation, groups were further subdivided into two subgroups for bulk‑fill and incremental methods. Universal Tofflemire Retainer and band were placed on the prepared cavities. The self‑etch adhesive was applied on all aspects of the preparations and then it was light‑cured using a light‑curing unit for 15 s. Now, cavities were restored with different esthetic materials and methods. In the bulk‑fill method, the MOD cavity was restored with a solitary increase of restorative material and light cured from all directions of tooth for 20 s each. In the incremental technique, the proximal box on both sides was reconstructed first in a gradual manner, in which two oblique increments and one horizontal increment were restored and treated for 20 s. Then, two oblique increments of material were used to reestablish the occlusal component, and it was once more light‑cured for 20 s. Fracture resistance was checked using a steel bar with a diameter of 4.5 mm that was positioned in the middle of the occlusal surface and a crosshead speed of 3 mm/ min, all of the samples were compressed axially loaded. Results: The fracture resistance of microhybrid composite resins in bulk technique was significantly higher than that of nanocomposites and Giomer. However, the fracture resistance of nanocomposite in the incremental method was significantly higher than the other two restorative materials. Conclusion: The quality of restoration depends both on the material and method used during the restoration procedure. Both factors are dependent on each other. Superior fracture resistance was shown by microhybrid composites when restored with the bulk‑fill technique and nanohybrid composites when restored with the incremental technique. [ABSTRACT FROM AUTHOR]

Resin infiltration (RI) is used to mask enamel opacities. There are three recommended etching cycles. However, anecdotal evidence suggests that favorable esthetics outcomes can be obtained by increasing the etching cycles. This study aimed to evaluate the effects of repeated etching cycles during RI application on esthetic changes and surface roughness of demineralized enamel at multiple treatment stages. Artificial demineralization was prepared on the buccal surface of ninety sound extracted premolars. The teeth were divided into nine groups (n = 10); with each consecutive group having one additional etching cycle up to nine etching cycles. Resin infiltrant was performed twice, first for 3 min (Resin 1) and again for 1 min (Resin 2). Surface roughness and esthetic changes were assessed using a profilometer (Ambios XP-200) and Minolta spectrophotometer, respectively, at baseline (sound enamel), etching, resin 1, resin 2, 7 days, and 28 days post resin applications. Data were analyzed with two-way ANOVA (p < 0.05). There was a significant interaction between the different stages and various groups of etching cycles on surface roughness, F(48, 126) = 3.48, p < 0.001. There was a significant interaction between the different stages and various groups of etching cycles on color changes, F(4, 126) = 1.177, p = 0.045. The surface roughness of demineralized enamel infiltrated with RI was less than that of sound enamel (baseline). There is a significant difference in color changes between resin 1 and resin 2 (p < 0.05). After five etching cycles, RI improved the esthetic of the color of teeth similar to the baseline. Surface roughness and color changes remained constant for 28 days. RI can be considered an effective and predictable treatment option for the restoration of early enamel lesions owing to its better surface characteristics and reliable masking effects. The color stability and surface roughness stay unaltered for up to 28 days. [ABSTRACT FROM AUTHOR]

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Background: The creation of the denture base material with bioactive properties that releases ions and produces hydroxyapatite. Methods: Acrylic resins were modified by the addition of 20% of four types of bioactive glasses by mixing with powders. Samples were subjected to flexural strength (1, 60 days), sorption and solubility (7 days), and ion release at pH 4 and pH 7 for 42 days. Hydroxyapatite layer formation was measured using infrared. Results: Biomin F glass-containing samples release fluoride ions for a period of 42 days (pH = 4; Ca = 0.62 ± 0.09; P = 30.47 ± 4.35; Si = 22.9 ± 3.44; F = 3.1 ± 0.47 [mg/L]). The Biomin C (contained in the acrylic resin releases (pH = 4; Ca = 41.23 ± 6.19; P = 26.43 ± 3.96; Si = 33.63 ± 5.04 [mg/L]) ions for the same period of time. All samples have a flexural strength greater than 65 MPa after 60 days. Conclusion: The addition of partially silanized bioactive glasses allows for obtaining a material that releases ions over a longer period of time. Clinical significance: This type of material could be used as a denture base material, helping to preserve oral health by preventing the demineralization of the residual dentition through the release of appropriate ions that serve as substrates for hydroxyapatite formation. [ABSTRACT FROM AUTHOR]

There are often bonding problems between acrylic resins and silicone. PEEK (polyetheretherketone), which is a high-performance polymer, has great potential for the implant, and fixed or removable prosthodontics. The aim of this study was to evaluate the effect of different surface treatments on PEEK to be bonded to maxillofacial silicone elastomers. A total of 48 specimens were fabricated from either PEEK or PMMA (Polymethylmethacrylate) (n = 8). PMMA specimens acted as a positive control group. PEEK specimens were divided into five study groups as surface treatments as control PEEK, silica-coating, plasma etching, grinding, or nano-second fiber laser. Surface topographies were evaluated by scanning electron microscopy (SEM). A platinum-primer was used on top of all specimens including control groups prior to silicone polymerization. The peel bond strength of the specimens to a platinum-type silicone elastomer was tested at a cross-head speed of 5 mm/min. The data were statistically analyzed (α = 0.05). The control PEEK group showed the highest bond strength (p < 0.05) among the groups. No statistical difference was found between control PEEK, grinding, or plasma etching groups (p > 0.05). The lowest bond strength was seen in the laser group, which was not statistically different from silica-coating (p > 0.05), and statistically different from control PEEK, grinding, or plasma groups (p < 0.05). Positive control PMMA specimens had statistically lower bond strength than either control PEEK or plasma etching groups (p < 0.05). All specimens exhibited adhesive failure after a peel test. The study results indicate that PEEK could serve as a potential alternative substructure for implant-retained silicone prostheses. [ABSTRACT FROM AUTHOR]

Compared with room temperature, the responsive curve of polymer humidity sensor usually presents a nonlinear shift and distortion at higher temperature conditions, this will sharply decrease the accuracy and working stability of polymer humidity sensor. In this paper, an organic–inorganic cross‐linked interpenetrating network (c‐IPN) between silocane compounds and acrylic prepolymer resin has been constructed to prepare a c‐IPN humidity‐sensitive material by in‐situ crosslinking reaction. The results shows that the prepared c‐IPN polymer humidity sensor shows more sensitive in range of 30–90% RH, with higher linearity coefficient of 0.9996 and lower hysteresis coefficient of 1.25% RH. And the c‐IPN polymer humidity sensor exhibits more higher stability at higher temperature than that at room temperature. Meanwhile, the temperature coefficient of the c‐IPN polymer humidity sensor can decrease to 0.53% RH/°C, along with temperature hysteresis curve linear coefficient increase to (R2 = −0.999), when (3‐aminopropyl) triethoxysilane is used at dosage of 10 wt.% druing crosslinking reaction. This study presents a feasible practical technical solution for developing novel high‐performance polymer humidity‐sensitive materials and its humidity sensors at wider temperature range. [ABSTRACT FROM AUTHOR]

Since few decades, researchers have continuously devoted significant efforts to develop coatings as an alternative approach to protect corrosion. Herein, a series of coatings containing various ratios of acrylic and epoxy resins were developed to investigate the corrosion protection on mild steel substrates. In addition, 1 wt% polydimethylsiloxane (PDMS) solution was incorporated as a modifier to enhance the corrosion protection performance and the hydrophobicity of the coatings. The chemical structures and thermal stability of the fabricated coatings were evaluated by the Fourier-Transform Infrared Spectroscopy (FTIR) and Thermogravimetric (TGA) analysis respectively. Furthermore, via the utilization of ultraviolet-visible (UV-Vis) spectroscopy and water contact angle (WCA) instrument, the degree of transparency and surface wettability of the coating samples were investigated. Electrochemical impedance spectroscopy (EIS) was employed to evaluate the corrosion protection performance of the coatings. Among all the coating samples, the EIS results revealed that the T1, T5, and T7 coating samples containing higher ratios of acrylic resin exhibited pronounced impedance modulus ( Z 0.01 H z ) values exceeding 10 10 Ω cm 2 throughout 60 days of exposure to the corrosive medium, 3.5 wt% NaCl solution. Moreover, this finding was supported by the breakpoint frequency measurement which showed that the T1 and T5 coating samples performed at a full capacitive region even after 60 days of immersion. From this investigation, it was concluded that the T5 coating sample exhibited optimum results, thus enhancing the overall corrosion protection performance. [ABSTRACT FROM AUTHOR]

Changes in the properties of resin-based polymers exposed to the oral environment can emerge when chlorhexidine (CHX) is incorporated to develop bioactive systems for treating denture stomatitis. Three reline resins loaded with CHX were prepared: 2.5 wt% in Kooliner (K), 5 wt% in Ufi Gel Hard (UFI), and Probase Cold (PC). A total of 60 specimens were submitted to physical aging (1000 cycles of thermal fluctuations, 5–55 °C) or chemical aging (28 days of pH fluctuations in artificial saliva, 6 h at pH = 3, 18 h at pH = 7). Knoop microhardness (30 s, 98 mN), 3-point flexural strength (5 mm/min), and surface energy were tested. Color changes (ΔE) were determined using the CIELab system. Data were submitted to non-parametric tests (α = 0.05). After aging, bioactive K and UFI specimens were not different from the controls (resins without CHX) in mechanical and surface properties. Thermally aged CHX-loaded PC specimens showed decreased microhardness and flexural strength but not under adequate levels for function. The color change was observed in all CHX-loaded specimens that underwent chemical aging. The long-term use of CHX bioactive systems based on reline resins generally does not impair removable dentures' proper mechanical and aesthetic functions. [ABSTRACT FROM AUTHOR]

The organosilicon modified cationic acrylic resin is prepared via solution polymerization technology, which butyl acrylate (BA), methyl methacrylate (MMA), styrene (St), vinyltriethoxysilane(VTES), dimethylaminoethyl methacrylate (DMAEMA) and hydroxy propyl methacrylate (HPMA) as the co-polymerized monomers, and proprylene glycol monomethyl ether (PGME) as solvent, and 2,2-azo-bis-iso-butyronitrile (AIBN) as the initiator to create a resin to introduce the Si-O bond into the polymer chains. The cathodic electrodeposition (CED) coatings were prepared by mixing the synthetic resin and blocked isocyanate. The influence of the amount of VETS on the resin and the resultant CED coatings is investigated in detail. The optimum amount of VETS is obtained, which is 5.0%. The hydrophobicity and the acid and alkaline resistance of the film are improved when VETS is introduced to co-polymerize with other monomers. [ABSTRACT FROM AUTHOR]

Background and Objectives: Acrylic resins remain the materials of choice for removable prosthesis due to their indisputable qualities. The continuous evolution in the field of dental materials offers practitioners today a multitude of therapeutic options. With the development of digital technologies, including both subtractive and additive methods, workflow has been considerably reduced and the precision of prosthetic devices has increased. The superiority of prostheses made by digital methods compared to conventional prostheses is much debated in the literature. Our study's objective was to compare the mechanical and surface properties of three types of resins used in conventional, subtractive, and additive technologies and to determine the optimal material and the most appropriate technology to obtain removable dentures with the highest mechanical longevity over time. Materials and Methods: For the mechanical tests, 90 samples were fabricated using the conventional method (heat curing), CAD/CAM milling, and 3D printing technology. The samples were analyzed for hardness, roughness, and tensile tests, and the data were statistically compared using Stata 16.1 software (StataCorp, College Station, TX, USA). A finite element method was used to show the behavior of the experimental samples in terms of the crack shape and its direction of propagation. For this assessment the materials had to be designed inside simulation software that has similar mechanical properties to those used for obtaining specimens for tensile tests. Results: The results of this study suggested that CAD/CAM milled samples showed superior surface characteristics and mechanical properties, comparable with conventional heat-cured resin samples. The propagation direction predicted by the finite element analysis (FEA) software was similar to that observed in a real-life specimen subjected to a tensile test. Conclusions: Removable dentures made from heat-cured resins remain a clinically acceptable option due to their surface quality, mechanical properties, and affordability. Three-dimensional printing technology can be successfully used as a provisional or emergency therapeutic solution. CAD/CAM milled resins exhibit the best mechanical properties with great surface finishes compared to the other two processing methods. [ABSTRACT FROM AUTHOR]

Packaging must have a good commercial appearance and is generally obtained by ink transferred to its substrate. It is important that the ink used in packaging printing is produced from environmentally friendly and sustainable raw materials as well as being suitable for the printing system. The increasing demand in the field of printed packaging and the scarcity of resources to meet this demand have accelerated the search for new sources for inks. For this purpose, inks produced in the laboratory using a modified cellulose‐based binder, a commercial acrylic resin and a commercial soybean protein were compared with a commercial ink. As a result of the study, it was determined that the printability properties of the ink obtained by using the modified cellulose‐based binder were better than the ink obtained with commercial soybean protein. It was determined that it showed printability properties close to the ink produced with commercial acrylic binders. By using modified cellulose‐based water‐based flexographic ink instead of other commonly used binders, more environmentally friendly sustainable inks can be produced. [ABSTRACT FROM AUTHOR]

Background: Splinted multiunit cement-retained restorations with screw access channels over engaging abutments are viable implant prosthetic options. However, information regarding the maximum degree of divergence between multiple implants is lacking. The purpose of this in vitro study was to determine the maximum degree of divergence between 2 adjacent implants with conical connections that allows insertion and removal of splinted restorations with engaging preparable abutments or titanium base abutments. Methods: Two implants were aligned in a stone base, one straight and the other at an angle ranging from 0 to 20 degrees. The implants represented an implant system that had an internal conical connection and a hexed abutment engaging the base of the connection. Two straight preparable engaging cement retained abutments were screwed onto the implants and splinted together using acrylic resin. A total of 11 angles were tested, with 7 specimens for every angle. Evaluation of dislodging force was performed by pulling out the splinted abutments after unscrewing them. This was performed subjectively by 3 blinded investigators who applied a tactile pulling force. A scale of 0–10 was used to estimate the pulling force. Objectively the dislodging force was measured in Newtons using a universal testing machine. A statistical correlation was made between the subjective and objective dislodging force values using Spearman's rank correlation coefficient. Results: The mean subjective values increased gradually from 0 to 16 degrees. A sudden rise was noticed at 18 degrees (9.71 ± 0.23) and, at 20 degrees, the investigators were not able to remove the splinted abutments from the implants. The mean objective dislodgement force values increased gradually from 0 to16 degrees and abruptly from 16 degrees (13.57 ± 0.45 N) to 18 degrees (25.40 ± 0.66 N) and 20 degrees (35.22 ± 0.64). The correlation between the subjective and the objective evaluations assessed using the Spearman's rank correlation coefficient was 0.98 indicating a statistically significant correlation (P <.001). As the objective dislodging force increased, the subjective dislodgement difficulty increased. Conclusions: Splinting cement retained restorations with screw access channels on engaging abutments is possible when multiple implants with conical connections having an internal flare angle of 8 degrees are used, with implant divergence of up to 16 degrees. [ABSTRACT FROM AUTHOR]

To fabricate a photocatalytic acrylic paint, TiO2 nanoparticles were surface modified by a bi-functional amino silane (i.e. bis-3-(aminopropyltriethoxysilane)) at different concentrations and applied at 1, 3 and 5 wt% to an acrylic latex. It was found that the surface modification of nano TiO2 enhanced its specific surface area about 42%. The tensile properties of the pristine and nanocomposite acrylic films were assessed. The photocatalytic degradation of aqueous solution and stain of methylene blue (MB) were evaluated (under solar, visible, and UV illuminations) by nanoparticles and nanocomposites, respectively. Results showed that incorporating 3 wt% of the pure and modified nano TiO2 to arylic film caused 62 and 144% increment in the tensile strength. The modified nanoparticles showed higher MB degradation contents under UV, visible and solar irradiation (82, 70, 48%, respectively). The addition of pure and modified nanoparticles to the acrylic film caused decrement in the water contact angle from 84 to 70 and 46°, respectively. It also caused considerable enhancement in the glass transition temperature (Tg) of acrylic film compared to the pristine and pure nanocomposite films (i.e. about 17 and 9 °C, respectively). Furthermore, it was found that the modified nanocomposite caused more color change of MB stain (65%). [ABSTRACT FROM AUTHOR]

Background: Several denture base materials have evolved over the years. Beginning with metal and ending up with various types of acrylic materials in order to have a biocompatible, antimicrobial denture base. A flexible acrylic resin, such as Polyamides, has been introduced to address the drawbacks of heat-cured PMMA resin. This study was conducted to examine the water solubility and water sorption of flexible thermoplastic polyamides (Valplast) and two types of conventional heat-cured acrylic resin (PMMA) (Acrostone, Vertex). Methods: Specimens of thermoplastic polyamides and two types of conventional PMMA (Acrostone, Vertex) resin were manufactured and used in the current investigation in accordance with manufacturer instructions. A total of 45 specimens were milled into discs with a diameter of 50.0 mm diameter, 5.0 mm thick. To ascertain conformity with ADA Standard No. 12, water solubility and water sorption were measured. Results: All items complied with ADA regulations for water solubility and sorption. Flexible thermoplastic polyamide displayed less water solubility, and water sorption than heat-cured PMMA. Acrostone showed the higher water solubility, sorption followed by Vertex heat cure acrylic resin both heat cured showed significant higher water solubility than polyamides Valplast). Conclusions: Within the limitations of this in vitro experiment, heat cure PMMA resin demonstrated significantly greater water solubility and water sorption when compared to thermoplastic polyamides. [ABSTRACT FROM AUTHOR]

The placement of orthodontic appliances into the oral area can lead to infection, inflammatory and gingival collapse. Using an antimicrobial and anti-inflammatory material in the matrix of orthodontic appliance may help to reduce these issues. This study aimed to assess the release pattern, the antimicrobial action and the flexural strength of self-cured acrylic resins after adding different weight percentages of curcumin nanoparticles (nanocurcumin). In this in-vitro study, 60 acrylic resin samples were divided into five groups (n = 12) based on the weight percentage of curcumin nanoparticles added to the acrylic powder (0 for control, 0.5, 1, 2.5, and 5%). Then, the dissolution apparatus was used for the release assessment of nanocurcumin form the resins. For antimicrobial action assessment, the disk diffusion method was used and a three-point bending test was performed with a speed of 5 mm/min to determine the flexural strength. Data were analyzed using one-way analysis of variance (ANOVA) and Post-Hoc Tukey tests (with p < 0.05 as significant level). The microscopic images showed the homogeny distribution of nanocuricumin in self-cured acrylic resins in varied concentrations. The release pattern showed a two-step release pattern for all concentrations of nanocurcumin. The one-way ANOVA outcomes indicated that adding curcumin nanoparticles to self-cured resin increased the diameter of the inhibition zones for the groups against Streptococcus mutans (S. mutans) significantly (p < 0.0001). Additionally, as the weight percentage of curcumin nanoparticles increased, the flexural strength decreased (p < 0.0001). However, all strength values were higher than the standard value (50 MPa). No significant difference was detected between the control group and the group with 0.5 percent (p = 0.57). Considering the proper release pattern and the potent antimicrobial activity of curcumin nanoparticles, then the preparing self-cured resins containing curcumin nanoparticles can be beneficial for antimicrobial aims without damaging the flexural strength to use in orthodontic removable applications. [ABSTRACT FROM AUTHOR]

Immobilization protocols for head and neck radiotherapy (HNR) are needed to reduce radiation dispersion in non-tumoral tissues and to reduce damage to noble structures; however, involuntary mandibular movements require additional adaptations of thermoplastic masks. Our objective was to describe an easy and low-cost disposition to help thermoplastic masks immobilize the mandible during HNR. We created Styrofoam models to stabilize the mandible which was used to make adaptation to the thermoplastic masks. The Styrofoam model was inserted into alginate to construct a mold and a self-curing acrylic resin was added into the mold. After the acrylic resin hardened, the dispositive mandibular immobilizer was removed from the alginate mold and adjusted with Maxicut and Minicut or other drills and sandpaper. The alginate mold can be used on the same day to create backup devices. Our device was made in a simple way, has a low cost, and helps the thermoplastic masks to immobilize the mandible, leading to a more precise individualization of head and neck immobilization that can reduce unanticipated radiation scatter and improve radiation distribution. [ABSTRACT FROM AUTHOR]

Copyright of Polimery is the property of Industrial Chemistry Research Institute 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.)

The article presents an electron magnetic resonance study of metal paints in terms of identification and selection of appropriate pigment components based on the summation of spectral components. Research was carried out to assess the durability of paints on the basis of the detection of free radicals in individual components, the occurrence of which leads to paint degradation. Two types of acrylic resins, three types of organic pigments, and titanium white, hardener, and clearcoat were tested. The g-factor as well as all electron magnetic resonance line parameters were calculated. Electron magnetic resonance is found to be useful in the effort to eliminate a paint component that reduces color durability and to select components in terms of paint quality. [ABSTRACT FROM AUTHOR]

Traditional hand instrumentation is a commonly used technique to perform pulpectomy in deciduous teeth by most specialists in pedodontics. Lately, dentists have embraced rotary instrumentation as a safe and effective alternative. This study aimed to compare the efficacy of root canal preparation in extracted primary molars between manual and two rotary file systems using micro-CT. Thirty-six extracted human second primary mandibular molars were divided into three groups according to the instrumentation method: (1) Manually instrumented (MI) group (n = 9) in which the teeth were treated using K-files up to size 30; (2) Kedo-Ssystem (KS) group (n = 9); (3) ProTaper Gold system (PTG) group (n = 10) and control group (n-8). Each tooth was scanned before and after the retrograde root canal preparation. Residual dentin volume was calculated using micro-CT scans to evaluate the technique's efficacy. Additionally, the preparation time and procedural errors were recorded for each tooth preparation. A one-way ANOVA test was carried out to compare the groups' dentin volume and preparation time. The mean preparation time using the manual method (13.14 min) was more than two times longer than that of the rotary techniques (4.62 min and 6.45 min). The manual preparation method using a K-file removed almost half the root canal material when compared with the rotor method (p = 0.025). Conclusion: our results suggest that rotary instrumentation is more efficient for root canal preparation in primary teeth than the traditional manual method. This finding may call for a paradigm shift in current clinical practices, where manual instrumentation is still commonly preferred. [ABSTRACT FROM AUTHOR]

Prefractionation of complex mixtures of proteins derived from biological samples is indispensable for proteome analysis via top-down mass spectrometry (MS). Polyacrylamide gel electrophoresis (PAGE), which enables high-resolution protein separation based on molecular size, is a widely used technique in biochemical experiments and has the potential to be useful in sample fractionation for top-down MS analysis. However, the lack of a means to efficiently recover the separated proteins in-gel has always been a barrier to its use in sample prefractionation. In this study, we present a novel experimental workflow, called Passively Eluting Proteins from Polyacrylamide gels as Intact species for MS ("PEPPI-MS"), which allows top-down MS of PAGE-separated proteins. The optimization of Coomassie brilliant blue staining followed by the passive extraction step in the PEPPI-MS workflow enabled the efficient recovery of proteins, separated on commercial precast gels, from a wide range of molecular weight regions in under 10 min. Two-dimensional separation combining offline PEPPI-MS with online reversed-phase liquid chromatographic separation resulted in identification of over 1000 proteoforms recovered from the target region of the gel (≤50 kDa). Given the widespread availability and relatively low cost of traditional sodium dodecyl sulfate (SDS)-PAGE equipment, the PEPPI-MS workflow will be a powerful prefractionation strategy for top-down proteomics.

Direct measurement of proteins from single cells has been realized at the microscale using microfluidic channels, capillaries, and semi-enclosed microwell arrays. Although powerful, these formats are constrained, with the enclosed geometries proving cumbersome for multistage assays, including electrophoresis followed by immunoprobing. We introduce a hybrid microfluidic format that toggles between a planar microwell array and a suspension of microparticles. The planar array is stippled in a thin sheet of polyacrylamide gel, for efficient single-cell isolation and protein electrophoresis of hundreds-to-thousands of cells. Upon mechanical release, array elements become a suspension of separation-encoded microparticles for more efficient immunoprobing due to enhanced mass transfer. Dehydrating microparticles offer improved analytical sensitivity owing to in-gel concentration of fluorescence signal for high-throughput single-cell targeted proteomics.

Objective: The surface of provisional restorations applied before conventional or implant- supported fixed restorations may cause bacterial or fungal biofilm formation. The aim of this study was to evaluate the antimicrobial activity of acrylic resins used in provisional restorations modified with chlorhexidine diacetate. Methods: 120 cylindrical, auto-polymerized resin samples modified with chlorhexidine diacetate were prepared at concentrations of 0 (control), 1, 3, 5 wt %. The antimicrobial activity was examined against Streptococcus mutans, Enterococcus faecalis, and Candida albicans using Crystal Violet quantification, MTT assay, and Scanning Electron Microscopy. Data were analyzed by ANOVA and paired sample t-tests (α=0.05). Results: The addition of chlorhexidine diacetate influenced the growth rate and metabolic activity of microorganisms. The antimicrobial effect against C. albicans and S. mutans statistically increased with the percentage of chlorhexidine diacetate. E. faecalis bacteria were less affected by chlorhexidine diacetate compared to other pathogens. Conclusion: It has been shown that the effectiveness of CHDA in inhibiting the proliferation of microorganisms correlated positively with increasing concentration levels. More research is needed to confirm the impact of different chlorhexidine concentrations on the mechanical properties, clinical efficacy, and antimicrobial properties of CDHA.

Aim: To assess the effect of different mechanical surface treatments on flexural strength of repaired denture base. Material and Methods: Sixty bar-shaped specimens of heat-polymerized acrylic resin were fabricated, and divided into six groups (n=10). All specimens, except the positive control group (group PC), were sectioned into halves to create a 1-mm clearance. A negative control group with no surface treatment (group NC) was also considered. Other groups underwent different surface treatments: group Laser; treated with erbium: yttrium-aluminum-garnet (Er:YAG) laser, group APA; airborne-particle abrasion (APA), group APA plus Laser; a combination of laser and APA, and group Bur; bur grinding. After measuring surface roughness (Ra) with a profilometer, all sectioned specimens were repaired by auto-polymerizing acrylic resin, and thermocycled afterward. Three-point bending test was performed by a universal testing machine. Data were statistically analyzed (α=0.05). Results: The mean surface roughness of all experimental groups were significantly higher than that of group NC (p

OBJECTIVE: To find the effect of artificial saliva, water and different percentages of polyvinyl chloride (PVC) on the flexural strength and microhardness of heat cure polymethylmethacrylate (HC-PMMA) denture base resin. METHODS: An in-vitro study conducted, from April-December, 2020, at the MRL University of Peshawar and Interdisciplinary Research Centre in Biomedical Materials (COMSATS) Lahore. Total of 100 specimens for five groups (n=20) denoted by A, B, C, D and E containing 0%, 5%, 10%, 15% and 20% PVC in HC-PMMA respectively were fabricated to test flexural strength. Each group was divided into two subgroups depending on immersion medium containing ten specimens each. Three-point bending test was used to determine flexural strength. Microhardness was determined using thirty (n=30) specimens through Vickers hardness tester. Statistical analysis was performed by using one way ANOVA and post hoc Tukey test. P-value

Background and Objective: Denture cleansing and disinfecting techniques include mechanical brushing and using ultrasonic units, as well as microwave radiation, in conjunction with various chemical cleansers. The present study investigated the effect of different ratios of vinegar and hydrogen peroxide on the color changes of hard heat acrylic resins. Materials and Methods: This experimental study was conducted on 40 specimens with 3×20×20 mm dimensions. Samples were divided into four groups: one control group and three experimental groups with a combination of two types of hydrogen peroxide and vinegar with ratios of 1:1, 3:1, and 3:1. Samples were immersed in disinfectant solution for 8 h every day for one month. Afterward, they were subjected to spectrophotometry to evaluate their color properties based on a, b, and L color parameters. The color changes of each sample were then calculated using the ΔE00 and ΔW ID parameters. Data were analyzed using ANOVA and Tukey HSD tests at a significance level of 0.05. Results: The mean and standard deviation of ΔE00 parameter in vinegar and hydrogen peroxide groups with 3:1, 1:1, and 1:3 ratios, and the control were equal to 0.75±0.1, 0.5±0.2, 1.57±0.2, and 0.03±0.01, respectively. The mean and standard deviation of ΔW ID parameter in vinegar and hydrogen peroxide groups with 3:1, 1:1, and 1:3 ratios, and the control group were 0.7±0.96, 0.48±0.12, 1.51±0.47, and 0.09±0.07, respectively. Conclusion: The highest color change and bleaching of base denture resin occurred in the group with the 3:1 ratio of hydrogen peroxide to the vinegar, which was significantly different from other groups (P

Introduction: the emerging manufacture technologies for dental restorations have brought new materials with them, such as 3D-printing resins and CAD/CAM discs for the manufacturing of denture bases. Currently, there is no rigorous mechanical characterization for these materials in the literature, apart from the ones reported in technical datasheets. Method: samples for mechanical characterization were manufactured with a conventional heat cure acrylic, a CAD/CAM polymethyl methacrylate (PMMA) disc and two 3D-printing resins. The samples were tested in a universal testing machine, according to ISO 20795-1 for flexural strength and elastic modulus. Compression strength was also determined under dry conditions. The average value of each property was calculated (n = 5). One-way ANOVA and Tukey’s multiple comparisons tests were used. Results: mean flexural strengths ranged from 78.35±2.99 to 87.48±4.47MPa, elastic moduli were between 2125.43±57.05 and 2277.72±58.46MPa, and compression strengths values ranged from 85.03±2.14 to 119.15±2.87MPa. Statistical analyses showed significant differences for flexural and compression strengths but did not show any difference for elastic moduli. Conclusions: all the tested materials met the minimum required specification for mechanical properties given by ISO 20795-1. From a mechanical point of view, the new materials for digital technologies, i.e., CAD/CAM disc and 3D-printing resins, are suitable for denture-base applications.

Background: Temporary crown resins are used prior to prosthesis placement, indicating the importance of aesthetics. The aim of this study was evaluate the color stability of various staining solutions according to the color of temporary crown resins using VITA EasyshadeⓇ V.Methods: The temporary crowns used were the powder-liquid type and included four shades. A total of 36 specimens were fabricated in the form of disks with a diameter of 1.8 mm and a depth of 2 mm. They were divided into four groups of nine each, and staining was performed for seven days by precipitation in 3 mL of three staining solutions composed of distilled water, black coffee, and red wine. Color and color stability evaluations were performed by a trained examiner using a digital spectrophotometer (VITA EasyshadeⓇ V). Color stability was analyzed using the ΔE value.Results: Because of the color stability evaluation using the ΔE value, the difference between three and seven days was significant in the specimen I and III groups (p＜0.05). Further, post hoc analysis showed that the ΔE value of red wine was significant, indicating that the color stability in red wine was low. The ΔE values in group II between days three and seven were statistically significant (p＜0.05). Post hoc analysis showed that distilled water, coffee, and wine had the highest ΔE values on day three. On day seven, the ΔE value for wine was significant, and the color stability was low. There was no significant difference in group IV according to the staining period and staining solution; therefore, color stability was high (p＞0.05).Conclusion: This study showed that most temporary resin restorations exhibited color stability in the staining solution. The darker the color of the temporary resin restoration, the higher the color stability against extrinsic staining.

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office 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.)

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office 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.)