Acrylic Resin

PURPOSE Aim of this study was to determine patients' preference to acrylic resin major connector analogues (MCA) that simulated strengthened major connector designs formulated for Ti-6Al-7Nb alloy. MATERIALS AND METHODS Four MCA namely wide design (Wide), design with 2 strengthening ridges (2SR), design with 1 strengthening ridge (1SR), and thick design (Thick) were fabricated using light-polymerizing acrylic resin for 10 patients with Kennedy Class I or II partially edentulous maxillary arches. They were asked to wear each MCA in the mouth for 30 seconds in 6 pairs, and to report their preference for each pair. Using these data the 4 MCA were ranked in a descending preference order for each patient. A within-subject comparison of preferences was performed with the Friedman test and multiple comparisons with Wilcoxon Signed Ranks test. RESULTS A statistically significant preference order was revealed: Wide, 1SR, 2SR, and Thick (P < 0.008). The wide design (P < 0.004) and t...

Acrylic based resins are frequently used in daily dental practice. The most common use of the materials includes denture bases and denture liners, temporary crowns and orthodontic appliances. In the mouth, properties and functional efficiency of applied acrylic resins depend on internal factors related to the methods and conditions of polymerization and on external factors that are related to the environment in which the material is placed. Residual monomer, which is released as a result of interaction of both sets of factors is often associated with irritation, inflammatory and allergic reactions of oral mucosa. The aim of this paper is to review literature dealing with the conditions of polymerization and biodegradation of acrylic resins under certain conditions in the oral cavity and their impact on oral health (reviewed literature available on Medline database during the past two decades.) Conclusion: Methods and conditions of acrylate polymerization, on the one hand, and proper...

This paper describes the methodology and practice-based research underpinning the development of a successful cleaning strategy for Eva Hesse's sculpture Addendum (1967, Tate Collection T02394). Research strands included: technical and art historical investigations to determine the materials and construction of the work of art and to define the aims of the conservation treatment; the production, soiling and accelerated ageing of mock-up samples using contemporary equivalent materials; and the systematic, iterative evaluation of soiling removal systems, which were further refined for appropriate use on the work of art. The comparative cleaning system evaluation was employed to determine options which offered optimal soiling removal efficacy and posed minimal risk to the work of art. Newly developed Nanorestore Gel ® Peggy series (i.e. polyvinyl alcohol (PVA) and polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP)-based hydrogels), designed for the cleaning of modern and contemporary art, were evaluated with a range of other gels, emulsifiers and cosmetic sponges and assessed through a combination of empirical observation, microscopy and spectroscopic techniques. Promising options, combined with tailored aqueous phases derived from trials on mock-up samples, were then evaluated on discreet areas of the sculpture. After extensive testing, the top papier mâché section of Addendum was surface cleaned using an aqueous solution applied with cosmetic sponges, and the ropes were surface cleaned using a modified version of Nanorestore Gel ® Peggy 5 (PVA/PVP) loaded with a tailored aqueous solution. The optimisation of this hydrogel, combined with the extensive supporting research, enabled the successful, low-risk, conservation treatment of Addendum for the first time since acquisition.

The erosion-corrosion test rigs are available in various forms of designs in the field of research. In ships, submarines and fluid flow pipe line, many rotating parts are getting failed due to erosion-corrosion wear. So in order to investigate the erosion-corrosion wear behavior of materials in different conditions it is important to develop a test rig with suitable specification. This study of erosion corrosion behavior helps us to select the best material for suitable applications with different conditions. In this present work, an attempt is made to develop a simple and economical erosion corrosion test rig by considering appropriate dimensions according to experimental requirements. Using this erosion-corrosion test rig tests can be easily carried out for evaluating the wear behavior of the different materials. The test setup has been tested by taking distilled water mixed with some SiC sand particles in tank to check the rate of weight loss of zinc samples with respect to number of parameters like speed, time, type of slurry and angle of impingement.

The thermal degradation of some sulfonic cationites namely Amberlite IR-120, Indion-223 and Indion-225 was investigated using instrumental techniques like thermal analysis (TG) and Scanning Electron Micros-copy (SEM). Fourier Transform Infrared Spectroscopy (FTIR) was used to characterize the resins degradation steps. The sulfonic cationites undergo degradation through dehydration, followed by decomposition of sulfonic acid functional groups liberating SO 2. The thermogravimetric analysis of above cationites at higher temperature up to 520˚C, show mass loss of 61.61% and 25.43% respectively for Indion-223 and Indion-225, while Amberlite IR-120 cationite get burned off completely.

Roy Lichtenstein's Whaam! (1963) is an iconic artwork in Tate's collection (T00897). Over the past 50 years, the painting has been on almost continuous display and had accrued a layer of deposited soiling, which resulted in the dampening of Lichtenstein's vibrant colours and the masking of numerous subtleties across the painting surface. This paper outlines the design and execution of an optimal soiling removal strategy for this challenging work; utilising collabora-tive, practice-based research. The conservation treatment employed was derived through an iterative process that reflected and supported the conservation decision-making process. The research strands included: technical and art historical investigations to determine the materials and construction of Whaam! and to define the aims of the conservation treatment; preparation of accelerated aged and artificially soiled test (mock-up) paint samples based on contemporary equivalent materials and a comparative evaluation of a range of established and novel soil-removal systems, followed by further tailoring for use on the work of art. The range of cleaning systems evaluated included free-solvents, gels and emulsifiers; which were documented using star diagrams, digital microscopy and infrared spectroscopy. After a rigorous process of assessment and refinement, the strategy taken forward to Whaam! included the use of a polyvinyl alcohol-based polymeric hydrogel (Nanorestore Gel ® Peggy 6), uploaded with tailored aqueous solutions. This process facilitated a low risk, controlled and even-removal of the soiling layer, enabling the successful treatment of this sensitive painting for the first time in the painting's history.

The Code of Federal Regulations specifically adopts the ASME Boiler and Pressure Vessel Code as the standards for diving systems in US waters. Not all hyperbaric systems are made to ASME standards. This paper presents methods used successfully to obtain US Coast Guard and other jurisdictional approval of non-ASME pressure vessels for human occupancy.

The aim of this study was to develop intumescent flame-retardant coatings that incorporate chicken eggshell (CES) waste as a novel eco-friendly bio-filler. Three flame-retardant additives, namely, ammonium polyphosphate phase II, pentaerythritol and melamine were mixed with flame-retardant fillers and acrylic binder to synthesize the intumescent coatings. The fire performance of the coatings was evaluated in accordance with 'BS 476: Part 6-Fire Propagation' and 'BS 476: Part 7-Surface Spread of Flame' test standards. It was found that 4 out of 5 of the coated specimens (B, C, D and E) neither showed surface spread of flame nor any afterglow combustion upon fire exposure. The addition of 5.0 wt% and 2.5 wt% eggshell bio-filler into formulations B and E, respectively, improved fire protection due to char formation, with better morphology, height and structure of the protecting shield. The filler compositions of samples D (3.4 wt% TiO2/3.3 wt% Al(OH)3/3.3 wt% Mg(OH)(2)) and E (2.5 wt% TiO2/2.5 wt% Al(OH)(3)/2.5 wt% Mg(OH)(2)/2.5 wt% CES) applied at a thickness of 1.5 +/- 0.2 mm achieved the lowest fire propagation index with a value of 4.5 and 5.0, respectively (BS 476 Part 6, Class 0 materials) which indicates excellent fire-stopping properties. The results showed that the coatings were effective in fire protection, with good qualities of water resistance, thermal stability, and adhesion strength. Significantly, coating E (with CES) has proved to be efficient in the protection of plywood against fire. (C) 2015 Elsevier B.V. All rights reserved.

http://ac.els-cdn.com/S0300944015000120/1-s2.0-S0300944015000120-main.pdf?_tid=f2da7420-e7cf-11e4-9797-00000aacb361&acdnat=1429584284_362644e4f6b3e9c76399db9986e7b128 
http://www.sciencedirect.com/science/article/pii/S0300944015000120

―The thermal degradation of polyacrylic carboxylic and polystyrene sulfonic cationites was investigated using thermal analysis (TG) combined with Scanning Electron Microscopy (SEM). Fourier Transform Infrared Spectroscopy (FTIR) was used to characterize the resins degradation steps. The carboxylic cationite undergoes degradation through dehydration forming polyanhydrides, decomposition of polyanhydrides through decarboxylation with elimination of CO 2 and CO. The sulfonic cationite undergoes degradation through dehydration, followed by decomposition of sulfonic acid functional groups liberating SO 2. It was observed that strong acid (–SO 3 H +) cationite shows small mass loss of 55%, as against 88% mass loss shown by low-acidity carboxylic cationite. The possible reason for small mass loss of sulfonic cationite is discussed.

En la actualidad, los materiales dentales de restauración y rehabilitación deben cumplir numerosos requisitos, entre ellos presentar niveles mínimos en sus propiedades mecánicas, como
resistencia al cizallamiento, dureza, resistencia a la tracción, resistencia
a la flexión y resistencia al impacto.
En ese sentido, el objetivo del presente estudio fue caracterizar
mecánicamente y comparar dos (2) resinas dentales termopolimerizables, de diferentes fabricantes (uno colombiano y
otro brasileño) y que son de amplio uso en el mercado local; sin
embargo, con precios diferentes (a razón de 1:1,5), por eso se realizó un análisis económico de ambas resinas comercializadas ampliamente en Lima. Es decir, este trabajo procura comprobar si existen diferencias significativas entre ambas resinas empleadas en este estudio.
Se concluyó que la resina brasileña presentó una mayor resistencia
al cizallamiento e impacto, en promedio 10 % y 36 %; en cuanto a la resistencia a la flexión, casi es igual que la resina acrílica colombiana; finalmente, en cuanto a la resistencia a la tracción y dureza, la resina colombiana fue superior en torno a aproximadamente más de 28% y 55% respectivamente. Asimismo, la resina colombiana tiene un mejor posicionamiento en el mercado local, pero es 55 % más cara que el producto brasileño.

The aim is to evaluate the flexural strength of acrylic resin bars depending on the addiction of glass fibers with or without previous 3-methacryloxypropyl-trimethoxysilane (silane) application. Short fibers (3 mm) were treated and added to an acrylic resin powder, being further mixed with acrylic liquid to create bars (25 × 2 × 2 mm) of 11 experimental groups (N = 10), according to the interaction of experimental factors: weight % of glass fibers: (0.5; 1; 3; 4; 6 and 7) and silane application (with silane (S) or without silane (N)). Flexural strength and scanning microscopy evaluation were performed (SEM). Data (MPa) were submitted to ANOVA and Tukey (α = 5%). A significant difference between groups was observed (p = 0.001): S7%(128.85 ± 35.76)a, S6% (119.31 ± 11.97)ab, S4% (116.98 ± 25.23)ab, N4% (107.85 ± 24.88)abc, S1% (96.29 ± 20.65)bc, S0.5% (89.29 ± 7.33)cd, S3% (89.0 ± 11.27)cd, N3% (86.79 ± 17.63)cd, N1% (85.43 ± 16.44)cd, Control (73.29 ± 25.0)de, N0.5% (59.58 ± 19.46)e. For N groups, it was not possible to include more than 4%wt fibers. SEM showed better fiber-resin interaction for S groups, and fractures around fibers on N groups. Previous silane application enables the addiction of greater quantity of glass fibers and better interaction with the acrylic resin resulting in higher flexural strength. Without silane, fibers seem to act as initial crack points due to poor interaction.

O presente artigo traz o registro do processo indutivo de criacao e exposicao do trabalho denominado Prisma . Orientada por conceitos como copia e repeticao de Gilles Deleuze, a investigacao da resina acrilica como material escultorico trouxe diversos questionamentos sobre alguns elementos artisticos, como a moldagem, repeticao, transparencia, luz e volume presentes no trabalho. O resultado obtido levou ao questionamento desses elementos artisticos diante do espaco expositivo na medida em que o Prisma foi concebido como um conjunto de cubos em resina transparente e com rachaduras em seu interior. Suas caracteristicas fisicas no local levam a refracao e distorcao das imagens ao seu redor, tanto o tornando visivel no espaco como imagem distorcida em seu volume, como tambem se relacionando com as fontes de luz especificas do lugar.

Evaluation of Vickers hardness of different types of acrylic ... Ana Paula Farina1, Doglas Cecchin2, Rodrigo Gonçalves Soares3, Andre´ Luıs Botelho3, Jessica Mie Ferreira Koyama Takahashi1, Marcelo Oliveira Mazzetto3 and Marcelo Ferraz Mesquita1 1Department of ...

Despite advances in materials and techniques, complete dentures made of acrylic resin experience an increase in the occlusal vertical dimension (OVD) during processing. Many factors that affect the OVD of complete dentures are known. However, no study has examined the effect of using high-expansion dental stone (type V) as an investing material on the OVD. This study investigated the effects of using a high-expansion dental stone as an investing material on changes in the OVD of complete dentures. Twenty sets of simulated upper and lower dentures were processed by the compression molding technique. Specimens were equally divided into 2 groups. In the dental stone type III (DST III) group, the lower, middle, and upper parts of a flask were filled with DST III. In the dental stone type V (DST V) group, the procedure was the same as in the DST III group, except that the middle layer was made of high-expansion DST V. Changes in the OVD were measured before and after denture processing. ...

In the present research, study the effect of adding two different types of reinforcing powders, which included: Bamboo (Ba) and Rice Husk (RH), that added with different weight fractions (2, 4, 6 and 8 wt. %), and with the selected size particles of (25µm and 75µm) on thermal behavior of heat Cure Poly (Methyl Methacrylate) such as thermal conductivity and thermal diffusivity in addition to the differential scanning calorimetry (DSC) analysis  and these tests were accomplished at temperature of laboratory. The PMMA properties which reinforced by (Ba and RH) powders are mainly influenced by the interfacial adhesion strength between the powders and the matrix, and in order to get better correlation between the natural powder and PMMA matrix, so the powders were treated with alkali (sodium hydroxide) solution prior to use as reinforcement materials. The results showed that the values of the thermal conductivity and thermal diffusivity increased with increasing of the weight fraction for both particle sizes (25 µm and 75 µm) of natural powders.

Purpose: The impact strength and the flexural properties of denture base materials are of importance in predicting their clinical performance upon sudden loading. This study compares the impact and transverse strengths and the flexural modulus of three denture base polymers. Materials and Methods: The investigation included a relatively new microwave-polymerized polyurethane-based denture material processed by an injection-molding technique, a conventional microwave-polymerized denture material, and a heat-polymerized compression-molded poly(methyl methacrylate) (PMMA) denture material. Impact strength was determined using a Charpy-type impact tester. The transverse strength and the flexural modulus were assessed with a three-point bending test. The results were subjected to statistical analysis using a one-way analysis of variance and the Scheffe test for comparison. Results: The impact strength of the microwave-polymerized injection-molded polymer was 6.3 kJ/m(2), while its flexural strength was 66.2 MPa. These values were lower than those shown by the two compression-molded PMMA-based polymers. The differences were statistically significant. The flexural modulus of the new denture material was 2,832 MPa, which was higher than the conventional heat-polymerized polymer but was comparable to the other microwave-polymerized PMMA-based polymer. The difference in the flexural modulus was statistically significant. Conclusion: In terms of the impact and flexural strengths, the new microwave-polymerized, injection-molded, polyurethane-based polymer offered no advantage over the existing heat- and microwave-polymerized PMMA-based denture base polymers. However, it has a rigidity comparable to that of the m microwave-polymerized PMMA polymer.

A provisionalization sequence is essential for obtaining a predictable final prosthetic outcome. An assessment of the mechanical behavior of interim prosthetic materials could orient clinicians towards selecting an appropriate material for each clinical case. The aim of this study was to comparatively evaluate the mechanical behavior—with compressive and three-point flexural tests—of certain 3D-printed and conventional resins used to obtain interim fixed dental prostheses. Four interim resin materials were investigated: two 3D-printed resins and two conventional resins (an auto-polymerized resin and a pressure/heat-cured acrylic resin). Cylindrically shaped samples (25 × 25 mm/diameter × height) were obtained for the compression tests and bar-shaped samples (80 × 20 × 5 mm/length × width × thickness) were produced for the flexural tests, observing the producers’ recommendations. The resulting 40 resin samples were subjected to mechanical tests using a universal testing machine. Addi...

Purpose: This study evaluated the effectiveness of different exposure times of microwave irradiation on the disinfection of a hard chairside reline resin.Materials and Methods: Sterile specimens were individually inoculated with one of the tested microorganisms (Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, and Bacillus subtilis) and incubated for 24 hours at 37°C. For each microorganism, 10 specimens were not microwaved (control), and 50 specimens were microwaved. Control specimens were individually immersed in sterile saline, and replicate aliquots of serial dilutions were plated on selective media appropriate for each organism. Irradiated specimens were immersed in water and microwaved at 650 W for 1, 2, 3, 4, or 5 minutes before serial dilutions and platings. After 48 hours of incubation, colonies on plates were counted. Irradiated specimens were also incubated for 7 days. Some specimens were prepared for scanning electron microscopic (SEM) analysis.Results: Specimens irradiated for 3, 4, and 5 minutes showed sterilization. After 2 minutes of irradiation, specimens inoculated with C. albicans were sterilized, whereas those inoculated with bacteria were disinfected. One minute of irradiation resulted in growth of all microorganisms. SEM examination indicated alteration in cell morphology of sterilized specimens. The effectiveness of microwave irradiation was improved as the exposure time increased.Conclusion: This study suggests that 3 minutes of microwave irradiation can be used for acrylic resin sterilization, thus preventing cross-contamination.

doi: 10.1111/j.1741-2358.2010.00400.x Evaluation of the efficacy of chemical disinfectants for disinfection of heat-polymerised acrylic resinObjective:  This study evaluated the efficacy of disinfectants on the internal aspect of heat-polymerised acrylic resin contaminated with microbial strains.Background:  Dentures absorb oral fluids and become contaminated by different microorganisms.Methods:  Two hundred and fifty rectangular specimens were made of heat-polymerised acrylic resin, and then divided into five groups corresponding to the microbial strains (Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, S. mutans and Enterococcus faecalis). After contamination, the specimens were immersed in 1 and 2% sodium hypochlorite and 2% glutaraldehyde for periods of 5, 10 and 15 min. The specimens were placed into tubes containing different broths and incubated at 35°C and then visually analysed. Turbidity in the medium indicated microbial growth. The Fisher’s exact test was used in the analysis of the results.Results:  The strain E. faecalis was the most resistant to the disinfectant solutions, and among them, glutaraldehyde was more effective than 2 and 1% hypochlorite for disinfection for 5 min; in the 10-min period there were no differences between the disinfectants. In 15 min of immersion, 1% hypochlorite and glutaraldehyde were more effective than 2% hypochlorite.Conclusions:  Disinfection for 10 min with 1% hypochlorite and glutaraldehyde is effective in disinfecting the internal aspect of heat-polymerised acrylic resin.

The impact strength and the flexural properties of denture base materials are of importance in predicting their clinical performance upon sudden loading. This study compares the impact and transverse strengths and the flexural modulus of three denture base polymers. The investigation included a relatively new microwave-polymerized polyurethane-based denture material processed by an injection-molding technique, a conventional microwave-polymerized denture material, and a heat-polymerized compression-molded poly(methyl methacrylate) (PMMA) denture material. Impact strength was determined using a Charpy-type impact tester. The transverse strength and the flexural modulus were assessed with a three-point bending test. The results were subjected to statistical analysis using a one-way analysis of variance and the Scheffé test for comparison. The impact strength of the microwave-polymerized injection-molded polymer was 6.3 kl/m2, while its flexural strength was 66.2 MPa. These values were...

Objectives of this study was to determine the frequency of general complications in patients wearing polymethylmethacrylate heat cure acrylic resin partial removable dental prostheses. This descriptive study was conducted during July 2013 to June 2014 at dental outpatient department of Liaquat University of Medical and Health Sciences Pakistan. Data relating to 110 patients were collected using a structured proforma, by methods of patient’s interview, clinical and radiographic examination. Data related to age, gender, location of prosthesis in the dental arch and various complications were recorded. Majority of patients were male with age from 21 to 60 years. Most of complications occurred in maxillary arch especially on right site of the arch. The most prevailing complications in general in this study were loss of retention (56%) mucosal changes (35%), loss of support (31%), discomfort/pain (29%) and loss of stability (26%). On the other hand the least prevalent complications were ...

Background and aims. Polymethyl methacrylate (PMMA) is widely used for the fabrication of removable prostheses. Silver nano-particles (AgNps) have been added to PMMA because of their antimicrobial properties, but their effect on the mechanical properties of PMMA is unknown. The aim of this study was to investigate the effects of AgNps on the tensile strength of PMMA. Materials and methods. For this study, 12 specimens were prepared and divided into two groups. Group 1 included PMMA without AgNps and group 2 included PMMA mixed with 5 wt% of AgNps. Tensile strength of the specimens was measured by Zwick Z100 apparatus. Statistical analysis was carried out by SPSS using t-test. Statistical significance was defined at P<0.05. Results. This study showed that the mean tensile strength of PMMA in group 2 was significantly lower than that in group 1. Therefore, the tensile strength decreased significantly after incorporation of silver nano-particles. Within the limitations of this study...