Flexural strength of heat-polymerized polymethyl methacrylate denture resin reinforced with glass, aramid, or nylon fibers.

STATEMENT OF PROBLEM: Despite the favorable properties of conventional PMMA used as a denture base material, its fracture resistance could be improved. PURPOSE: This in vitro study was performed to determine whether the flexural strength of a commercially available, heat-polymerized acrylic denture base material could be improved through reinforcement with 3 types of fibers. MATERIAL AND METHODS: Ten specimens of similar dimensions were prepared for each of the 4 experimental groups: conventional acrylic resin and the same resin reinforced with glass, aramid, or nylon fibers. Flexural strength was evaluated with a 3-point bending test. The results were analyzed with a 1-way analysis of variance. RESULTS: All reinforced specimens showed better flexural strength than the conventional acrylic resin. Specimens reinforced with glass fibers showed the highest flexural strength, followed by aramid and nylon. CONCLUSION: Within the limitations of this study, the flexural strength of heat-polymerized PMMA denture resin was improved after reinforcement with glass or aramid fibers. It may be possible to apply these results to distal extension partial denture bases and provisional fixed partial dentures.     

Impact strength of denture polymethyl methacrylate reinforced with different forms of E-glass fibers

Abstract

Objective. The purpose of this in vitro study was to determine the reinforcing effect of different forms and concentrations of E-glass fibers on impact strength of denture polymethyl methacrylate. Materials and method. A total of 91 rectangular specimens (84 specimens for test groups and seven for control group) of a heat-cured acrylic resin were fabricated. The test specimens were prepared by modifying the polymethyl methacrylate with the addition of different concentrations (2.5%, 3%, 4%, 5% by volume) of three types (chopped strand mat, woven and continuous unidirectional fibers) of E-glass fibers. The impact strength was evaluated using the Charpy method. Results. While the 5% continuous glass fiber added test group showed the highest mean impact strength, the lowest value belonged to the 2.5% woven glass fiber containing group. When the impact strength values of chopped strand mat and continuous unidirectional glass fiber added groups at all concentrations were compared with the control group, the differences were statistically significant. The impact strength values of the woven glass fiber added groups at all concentrations were higher than that of the control group. However, the difference was non-significant. Conclusion. The impact strength of PMMA was enhanced by including E-glass fibers, increasing parallel with the fiber concentration.     

Silver distribution and release from an antimicrobial denture base resin containing silver colloidal nanoparticles

Purpose: The aim of this study was to evaluate a denture base resin containing silver colloidal nanoparticles through morphological analysis to check the distribution and dispersion of these particles in the polymer and by testing the silver release in deionized water at different time periods. Materials and Methods: A Lucitone 550 denture resin was used, and silver nanoparticles were synthesized by reduction of silver nitrate with sodium citrate. The acrylic resin was prepared in accordance with the manufacturers’ instructions, and silver nanoparticle suspension was added to the acrylic resin monomer in different concentrations (0.05, 0.5, and 5 vol% silver colloidal). Controls devoid of silver nanoparticles were included. The specimens were stored in deionized water at 37°C for 7, 15, 30, 60, and 120 days, and each solution was analyzed using atomic absorption spectroscopy. Results: Silver was not detected in deionized water regardless of the silver nanoparticles added to the resin and of the storage period. Micrographs showed that with lower concentrations, the distribution of silver nanoparticles was reduced, whereas their dispersion was improved in the polymer. Moreover, after 120 days of storage, nanoparticles were mainly located on the surface of the nanocomposite specimens. Conclusions: Incorporation of silver nanoparticles in the acrylic resin was evidenced. Moreover, silver was not detected by the detection limit of the atomic absorption spectrophotometer used in this study, even after 120 days of storage in deionized water. Silver nanoparticles are incorporated in the PMMA denture resin to attain an effective antimicrobial material to help control common infections involving oral mucosal tissues in complete denture wearers.     

Impact strength of denture polymethyl methacrylate reinforced with continuous glass fibers or metal wire

The impact strength of heat-cured acrylic resin test specimens that had been reinforced in various ways was compared in this study. Ten rectangular test specimens were fabricated for each test group. The strengtheners included 1.0-mm-diameter steel wire and continuous E-glass fibers. Both notched and unnotched test specimens were tested in a Charpy-type impact test. In a further analysis the concentration of glass fibers in the test specimens was determined and plotted against the impact strength of the test specimens. The results showed that, compared with the unreinforced specimens, both types of reinforcement increased the impact strength of the test specimens considerably (p < 0.001). There was no clear difference between the mean impact strength value of the test specimens reinforced with metal wire and that of the specimens reinforced with glass fiber. The correlation coefficient between the fiber concentration of the test specimens and their impact strength was 0.818 (p < 0.005). Specimens with fiber concentrations greater than 25 wt% yielded to the higher impact strength more readily than those with metal wire reinforcement did.     

聚甲基丙烯酸甲酯义齿基托材料聚合成型工艺的研究进展

本文着重介绍了聚甲基丙烯酸甲酯(PMMA)义齿基托材料的热压注塑成型、电热聚合固化、微波固化及快速自控气压和液压热聚合等固化成型模式的工作原理、方法、创新点及存在的缺陷等，初步探讨了PMMA义齿基托材料在其聚合成型工艺方面的研究进展。     

Effect of fiber reinforcement on impact strength of heat polymerized polymethyl methacrylate denture base resin: in vitro study and SEM analysis

PURPOSE

The aim of this in-vitro investigation was to describe the effect of reinforcement with different fibers on impact strength of heat polymerized polymethyl methacrylate (PMMA) denture base resin and to analyze the effect of surface treatment of the fibers on the impact strength.

MATERIALS AND METHODS

The specimens were fabricated from the dies formed as per standard ASTM D4812. 2% by weight of glass, polyethylene and polypropylene fibers were incorporated in the PMMA resin. The Izod impact testing was performed on the unnotched specimens and the values obtained were analyzed using appropriate one way ANOVA, followed by unpaired t-test. Fractured ends of the samples were subjected to the SEM analysis.

RESULTS

The polypropylene fibers with plasma treatment showed the highest impact strength (9.229 × 10² J/m) followed by the plasma treated polyethylene fibers (9.096 × 10² J/m), untreated polypropylene fibers (8.697 × 10² J/m), untreated polyethylene fibers (7.580 × 10² J/m), silane treated glass fibers (6.448 × 10² J/m) and untreated glass fibers (5.764 × 10² J/m). Also the surface treatment of all the fibers has shown the significant improvement in impact strength. Findings of the SEM analysis justified the improvement in impact strength after surface treatment.

CONCLUSION

Reinforcement with the fiber is an effective method to increase the impact strength of PMMA denture base resin. The surface treatment of fibers further increases the impact strength significantly.     

Bond strength of three chairside crown reline materials to milled polymethyl methacrylate resin

Statement of problemInformation on the bond strength of milled polymethyl methacrylate interim restorations when relined with chairside reline materials is lacking.PurposeThe purpose of this in vitro study was to measure the shear bond strength of various combinations of 3 different chairside reline materials bonded to milled polymethyl methacrylate blocks with 3 different types of surface treatments.Materials and methodsUniform blocks (10×10×22 mm) were milled from tooth-colored polymethyl methacrylate disks (Vivid PMMA; Pearson Dental Supply Co). The surface treatments tested were airborne-particle abrasion with 50-μm particle size aluminosilicate, application of acrylic resin monomer (Jet Liquid; Lang Dental Manufacturing Co) for 180 seconds, and airborne-particle abrasion with monomer application. The control groups were blocks with no surface treatment. The chairside reline materials tested were Jet acrylic resin (Jet Powder; Lang Dental Manufacturing Co), bis-acryl resin (Integrity; Dentsply Sirona), and flowable composite resin (Reveal; Bisco). All materials were applied through a Ø1.5×3-mm bonding ring. Ten specimens for each of the 12 groups were tested in a universal testing machine. Load was applied at a crosshead speed of 1 mm/min. Fracture surfaces were then analyzed for cohesive versus adhesive or mixed failure. Data were analyzed using 2-way ANOVA and Tukey-Kramer post hoc analysis (α=.05).ResultsThe mean shear bond strength values ranged from 1.77 ±0.79 MPa to 28.49 ±5.75 MPa. ANOVA revealed that reline material (P<.05), surface treatment (P<.05), and their interactions (P<.05) significantly affected the shear bond strength among the experimental groups. The strongest combination was Jet acrylic resin applied on specimens treated with airborne-particle abrasion and monomer. All 3 failure modalities (adhesive, cohesive, and mixed modes) were observed.ConclusionsOf the materials tested, the most reliable material to bond to milled polymethyl methacrylate was Jet acrylic resin, and the bond strength values were increased substantially when the milled polymethyl methacrylate surface was airborne-particle abraded and monomer was applied.     

Effect of polyaramid fiber reinforcement on the strength of 3 denture base polymethyl methacrylate resins

Purpose The interactive effects of synthetic polyaramid reinforcement fibers on the transverse strength of intact and repaired heat‐polymerized denture base acrylic resins were investigated. Materials and Methods Three polymethylmethacrylate (PMMA) polymers were tested: Acron MC (GC International Corp, Scottsdale, AZ), Lucitone 199 (Dentsply International Inc, York, PA), and Microlon (The Hygienic Corp, Akron, OH). With each polymer, there were 2 controls and 4 experimental groups (n = 9 per group). The treatment groups were intact heat‐polymerized PMMA control, PMMA with unreinforced repair, PMMA with polyaramid reinforced repair, intact polyaramid reinforced heat‐polymerized PMMA control, polyaramid reinforced PMMA with unreinforced repair, and polyaramid reinforced PMMA with polyaramid reinforced repair. The transverse fracture strengths of the samples were measured with a 3‐point bending test on a Zwick Universal Testing Machine (Zwick of America, Inc, East Windsor, CT). Results The highest mean strength at fracture was recorded with intact polyaramid reinforced heat‐polymerized PMMA controls for all resins. Analysis of variance showed significant differences in transverse strength (p < .05 ) by experimental group, by material, and by interaction of group and material. Tukey HSD (honestly significant difference) Multiple Comparisons Test (α= 0.05) showed that intact polyaramid reinforced heat‐polymerized PMMA controls were significantly stronger than intact heat‐polymerized PMMA controls and all the other treatment groups. Use of polyaramid reinforcement in repair of unreinforced PMMA or polyaramid reinforced PMMA did not result in significantly increased transverse strength. Conclusions Polyaramid reinforcement significantly increased the transverse strength of intact heat‐polymerized PMMA. Polyaramid fibers did not significantly increase strength to reinforce PMMA repairs.     

不同分散方法对纳米ZrO2/PMMA复合材料挠曲强度的影响

目的:研究不同分散方法对氧化锆(zrO2)纳米填料/聚甲基丙烯酸甲酯(PMMA)复合材料试件挠曲强度的影响.方法:在丙酮溶液中用硅烷偶联剂Z-6030对纳米ZrO2颗粒进行表面修饰,将经过表面修饰后的纳米ZrO2颗粒按照3%的添加量加入到义齿基托树脂Ⅱ型粉剂中,然后分别采用手工、球磨和超声湿混3种方法予以分散混合,并以不添加纳米ZrO2颗粒的PMMA作为空白对照组,再与Ⅱ型液剂反应后制成4组标准试件,最后进行三点弯曲测试.实验数据采用SAS6.12软件包进行单因素方差分析,均数间进行两两比较(Newman-Keuls检验).结果:复合材料的挠曲强度以球磨组最高,达73.64 MPa,手工混合组最低,为62.86 MPa.球磨、超声2组的挠曲强度显著高于手工组和空白对照组(P<0.05).球磨和超声2组之间无显著差异(P>0.05).结论:以球磨、超声2种方法混合纳米ZrO2颗粒和PMMAⅡ型粉剂,可得到较好的分散效果,从而提高复合树脂的挠曲强度.     

芳纶纤维增强聚甲基丙烯酸甲酯基托的机械性能

目的：研究芳纶纤维增强聚甲基丙烯酸甲酯（ＰＭＭＡ）基托的机械性能。方法：将Ｔｗａｒｏｎ，ＡＰＭＯＣ芳纶纤维分别按体积分数１％、２％埋入ＰＭＭＡ基托树脂内，然后测定芳纶纤维增强ＰＭＭＡ基托的弯曲强度、冲击强度及弹性模量。结果：１％、２％芳纶纤维各组与对照组相比，弯曲强度、冲击强度均有明显提高（Ｐ＜０．０１），但弹性模量没有明显提高（Ｐ＞０．０５）。结论：芳纶纤维能提高ＰＭＭＡ基托的弯曲强度和冲击强度。     

载银基托树脂的抗菌性及长效性研究

目的研究载银基托树脂的抗菌性及长效性。方法将载银基托树脂进行加速老化处理,然后采用薄膜密着法检测新鲜、老化抗菌基托树脂组对变形链球菌、白念珠菌的抑菌性,并进行方差分析比较。结果经过培养,载银基托树脂表面变形链球菌、白念珠菌数量较对照组明显下降。新鲜、老化组对变形链球菌的抑菌率分别为86.6%、84.2%,对白念珠菌的抑菌率分别为52.5%、49.6%,两组间差异无显著性。结论载银基托树脂能良好、持久地抑制细菌、真菌。     

Development of 3D printed dental resin nanocomposite with graphene nanoplatelets enhanced mechanical properties and induced drug-free antimicrobial activity

ObjectivesOral prosthetic rehabilitation has been used for a long time to restore function and natural appearance; however, it is still one of the most challenging areas in dentistry due to its technical fabrication process and biological behavior. Considering the advantages of additive manufacturing technology, this study introduced the feasibility of developing a 3D printed resin-based composition modified with graphene nanoplatelets (GNPs) to improve properties.MethodsAcrylate-based resin was impregnated with different concentrations of GNPs (0.0–0.25 wt%), and then different aspects such as mechanical, physical, biological and antimicrobial were analyzed to evaluate the effectiveness. TEM and SEM were used to characterize GNPs and their existence within the resin. Surface topography and roughness were evaluated using AFM. The degree of conversion and composition were confirmed by FTIR. Mechanical properties were detected using bending strength, microhardness and nanoindentation. Biocompatibility and antimicrobial activities were assessed with oral fibroblast and Candida albicans (C. albicans), respectively. In addition, most of the measurements were performed repeatedly after 3 months of storage in artificial saliva to evaluate performance.ResultsGNPs improved strength significantly at low concentrations ≤ 0.05 wt%, while the addition up to 0.25 wt% enhanced printed nanocomposite hardness and elasticity. The modification did not induce a toxic response, as its biocompatibility was within the recommended range of biomedical devices. Antimicrobial activity was of prominence, as GNPs showed an outstanding route of reducing C. albicans activity associated with filler proportion.SignificanceThe embedment of GNPs in 3D printed resin can become a key material for customized applications that require high antimicrobial, stiffness and strength properties.     

Flexural strength of a provisional resin material with fibre addition

The effect of fibre addition on the flexural strength of a resin was studied. A provisional material (ALIKE^®; GC America Inc.) was used as the control and resinous matrix. Silane treated glass fibre was selected for the reinforcing treatment. In order to determine the geometric influence on the strength, ordered fibres (1 w/o) were immersed within a resinous matrix in four different locations. In addition, randomly dispersed fibres, 5 mm in length, were blended at 1 w/o up to 8 w/o with acrylic powder and moulded into rectangular specimens (34 mm × 9 mm × 8 mm) with P : L = 2 : 1. Ten specimens were prepared for each group. A three‐point flexural test was run using a span of 25 mm at a rate of 5 mm/min. The strength values were collected and analysed with ANOVA and Scheffe tests. The strengths of the specimens with orientated fibre addition ranged from 49·4 (s.d. = 5·7) to 64·5 (6·7) MPa and the control was 54·3 (4·0) MPa. In the dispersed groups, the strengths obtained ranged from 55·9 (5·9) to 87·3 (7·9) MPa. The results disclosed that inclusion of orientated fibres horizontally on the tension side of the specimens significantly improved the flexural strength compared with the control ( P < 0·05). An optimal strength was obtained in the group of provisional resin containing 5 w/o dispersed fibre. Incorporation of glass fibres significantly improved the flexural strength of the resin and the dispersed method is more efficient than the orientated inclusion method.     

Flexural strength and modulus of a step-cured resin composite

In an attempt to reduce marginal contraction gaps, a step-curing mode of light polymerization of resin composite has been proposed. It was hypothesized that such an exposure mode, having an initial reduced curing rate, would result in composite having a lower modulus of elasticity than composite exposed in one step. The composite was initially exposed to power density levels of 50, 100, 150, or 200 mW/cm2 for durations of 10, 20, or 40 s. The final exposure and the exposure of the control group were performed at 750 mW/cm2 for 20 s. It was found that certain modes of two-step exposure resulted in a lower flexural modulus than did a one-step exposure of constant, high power density. Regression analysis showed, with statistical significance, that flexural modulus was relatively high following a short initial exposure at low power density or using a long initial exposure at high power density. Conversely, flexural modulus was relatively low following a long initial exposure at low power density or using a short initial exposure at high power density. The results were explained by probable differences in degree of conversion and cross-link density of the polymer network.     

Effect of incorporation of 2-tert-butylaminoethyl methacrylate on flexural strength of a denture base acrylic resin

Polymethyl methacrylate (PMMA) resins have commonly been used as a denture base material. However, denture bases may act as a reservoir for microorganisms and contribute to oral diseases in denture wearers. It is hypothesized that the 2-tertbutylaminoethyl methacrylate (TBAEMA) incorporated to acrylic resins should have antimicrobial activity related to the presence of amino groups on acrylic resin surface.

Objectives

The objectives of this study were to evaluate the presence of amino groups on acrylic resin surface and the influence on flexural strength after incorporation of TBAEMA.

Material and Methods

Six groups were divided according to the concentration of TBAEMA incorporated to acrylic resin (Lucitone 550): 0, 0.5, 1.0, 1.5, 1.75 and 2%. Specimens surface were evaluated by electron Spectroscopy for Chemical Analysis (ESCA) to detect the presence of amino groups, represented by nitrogen ratios. Flexural strength of the specimens was tested and results were analyzed by ANOVA and Tukey''s test (α=0.05).

Results

Different nitrogen ratios were observed on specimen surfaces: 0, 0.13, 0.74, 0.66, 0.92 and 0.33% for groups 0, 0.5, 1.0, 1.5, 1.75, and 2%, respectively. Significant differences were found for flexural strength (p<0.001). The mean flexural strength values were 98.3±3.9, 93.3±3.2, 83.9±2.1, 82.8±5.2, 71.2±5.1 and 17.3±3.2 MPa for groups 0, 0.5, 1.0, 1.5, 1.75, and 2%, respectively.

Conclusion

Within the limitations of this study, the incorporation of TBAEMA results in the presence of the potentially antimicrobial amino groups on specimen surfaces, but affect the flexural strength, depending on the concentration of TBAEMA.     

A biocompatibility study of a reinforced acrylic-based hybrid denture composite resin with polyhedraloligosilsesquioxane

Acrylic-based denture materials have several common weak points, such as shrinkage after curing, lack of strength and toxicity. In order to solve these problems, we adapted a hybrid system using acrylic polymer and polyhedraloligosilsesquioxane (POSS). The aim of the study was to investigate the biocompatibility of a reinforced acrylic-based hybrid denture composite resin with POSS. Specimens of a novel polymeric denture base resin, in which POSS was used to partially replace the commonly used base monomer, were fabricated. In order to examine changes in biocompatibility with time, fresh specimens, along with specimens soaked in distilled water for 24 and 72 h were fabricated. Three other types of acrylic denture base resins were used to prepare the resin specimens. Biocompatibility (as measured by a metabolic assay, an agar overlay test, and a mutagenesis assay) of the composites was tested. The metabolic and mutagenesis assays were conducted with pure culture medium as a control. In this study, the reinforced acrylic-based hybrid denture composite resin with POSS showed improved biocompatibility and lower mutagenicity than the control. Statistical examinations showed the cell metabolic activity of the novel polymeric denture base resin in the 72-h immersion case as having almost the same inclination as the control. We hope that these results might aid in the development of a reinforced acrylic-based denture resin.     

纳米载银树脂中抗菌剂的分散及银离子析出的观察

目的 研究纳米载银树脂中抗菌剂的分散及银离子的析出情况,为进一步研究其加工工艺、抗菌长效性及使用安全性提供依据.方法 用球磨法将以磷酸复盐为载体的纳米载银抗菌剂STR-1按一定比例添加到义齿基托聚合物粉体中,制作抗菌剂浓度分别为0、5和10 g/L的3组纳米载银树脂片各6片,其中3片规格为10 mm×10 mm×1 mm,用于扫描电镜观察树脂片表面抗菌剂的分散情况;另外3片规格为70 mm×70 mm×2.5 mm,分别浸泡在人工唾液中,每24 h取样1次,用电感耦合等离子质谱法测定银离子的平均析出量,观察54 d.结果 扫描电镜下可见纳米载银抗菌剂在树脂片中分散较均匀,有少量较小的团聚体,无大的团聚体形成;抗菌剂含量为5 g/L和10 g/L的纳米载银树脂片在人工唾液中浸泡54 d后累积析出银离子分别为0.953 μg和2.520 μg,分别占各自银离子总含量的0.026%和0.034%.银离子析出速度非常缓慢,银离子累积析出曲线呈"S"型,早期析出缓慢,中期析出相对加速,后期又趋于缓慢、稳定.结论 纳米载银抗菌剂STR-1可较均匀地分散于树脂中,54 d内纳米载银树脂中银离子析出微量且速度缓慢.     

聚甲基丙烯酸甲酯微球改型的人工树脂牙耐磨性能和硬度的研究

目的研究比较聚甲基丙烯酸甲酯（PMMA）微球改型的人工树脂牙与另外5种常人工树脂牙的耐磨耗特性和硬度。 方法本实验选取6种人工牙（3种高交联树脂牙：Vita Lingoform,Premium,Portrait IPN;2种合成树脂牙Yamahachi PX,Kaiplus和传统的PMMA树脂牙Yamahachi FX,n= 8）,其中Vita Lingoform为PMMA微球改型的新型树脂牙。另外,选取牙釉质样本为对照组。使用高温微动摩擦试验机进行反复滑动摩擦实验后用三维轮廓扫描仪确定磨痕的深度损失和体积损失,并用微压痕法测定各组样本的维氏硬度,分析统确定各组样本之间磨耗损失和硬度的差异以及人工树脂牙的磨耗损失与维氏硬度值进行相关性分析。 结果磨痕分析结果显示,6种人工树脂牙以及牙釉质的磨耗损失（深度损失μm,体积损失mm³ × 10^-3）差异有统计学意义（H_深度损失 = 95.01,H_体积损失 = 93.96,P<0.001）。加入PMMA微球的Vita Lingoform组树脂牙的磨耗损失量（1.58,1.377）低于传统的PMMA树脂牙Yamahachi FX（2.22,1.983,P<0.001）,但高于复合树脂牙Yamahachi FX和Kaiplus（1.01 ~ 1.06,0.935 ~ 0.990,P<0.05）。同时,Vita Lingoform组树脂牙组（37.2）的硬度低于复合树脂牙组（41.0 ~ 43.1,P<0.05）,高于传统的PMMA树脂牙Yamahachi FX（25.9,P<0.001）。高交联组树脂牙Premium和Portrait IPN的磨耗损失量（1.57 ~ 1.64,1.360 ~ 1.409）和硬度（36.1 ~ 37.4）与Vita Lingoform组差异均没有统计学意义（P>0.05）。6种人工树脂牙的耐磨性能和硬度均低于牙釉质对照（0.31,0.213;68.2,P<0.001）。相关性分析的结果显示,硬度与深度损失（r = -0.896）和体积损失（r = -0.893）均成负相关性。 结论PMMA微球改型的树脂牙耐磨性能和硬度均高于传统的丙烯酸树脂牙,但低于复合树脂人工牙和天然牙釉质,且与其他高交联人工树脂牙差异不大。     

Flexural strength and moduli of hypoallergenic denture base materials

STATEMENT OF PROBLEM: Hypoallergenic denture base materials show no residual methyl methacrylate (MMA) or significantly lower residual MMA monomer content compared to polymethyl methacrylate-based (PMMA) heat-polymerizing acrylic resin. There is insufficient knowledge of the mechanical properties of hypoallergenic denture base materials to warrant their use in place of PMMA-based acrylic resins for patients with allergic reaction to MMA. PURPOSE: This in vitro study compared flexural strength and flexural modulus of 4 hypoallergenic denture base materials with flexural strength/modulus of a PMMA heat-polymerizing acrylic resin. MATERIAL AND METHODS: The following denture base resins were examined: Sinomer (heat-polymerized, modified methacrylate), Polyan (thermoplastic, modified methacrylate), Promysan (thermoplastic, enterephthalate-based), Microbase (microwave-polymerized, polyurethane-based), and Paladon 65 (heat-polymerized, methacrylate, control group). Specimens of each material were tested for flexural strength and flexural modulus (MPa, n = 5) according to ISO 1567:1999. The data were analyzed with 1-way analysis of variance and the Bonferroni-Dunn multiple comparisons post hoc analysis for each test variable (alpha=.05). RESULTS: Flexural strength of Microbase (67.2 +/- 5.3 MPa) was significantly lower than Paladon 65 (78.6 +/- 5.5 MPa, P <.0001). Flexural strength of Polyan (79.7 +/- 4.2 MPa, P =.599), Promysan (83.5 +/- 3.8 MPa, P =.412), and Sinomer (72.3 +/- 2.1 MPa, P =.015) did not differ significantly from the control group. Significantly lower flexural modulus was obtained from Sinomer (1720 +/- 30 MPa, P =.0007) compared to the PMMA control group (2050 +/- 40 MPa), whereas the flexural modulus of Promysan (2350 +/- 170 MPa, P =.0005) was significantly higher than the PMMA material. Microbase (2100 +/- 210 MPa, P =.373) and Polyan (2070 +/- 60 MPa, P =.577) exhibited flexural modulus similar to the PMMA material. The tested denture base materials fulfilled the requirements regarding flexural strength (>65 MPa). With the exception of Sinomer, the tested denture base resins passed the requirements of ISO 1567 regarding flexural modulus (>2000 MPa). CONCLUSION: Flexural modulus of Promysan was significantly higher than the PMMA material. Microbase and Sinomer exhibited significantly lower flexural strength and flexural modulus, respectively, than PMMA. The other groups did not differ significantly from the control group.