不同聚合方法对基托树脂挠曲强度影响的实验研究

目的在实验室条件下比较2种义齿基托树脂经过4种聚合方法处理后基托树脂的挠曲强度，为临床选择适宜的聚合方法提供依据。方法用金属模具制备相同尺寸的蜡型96个，失蜡后使用2种品牌的义齿基托树脂填胶，用4种方法进行热处理使其固化，用万能力学实验机检测基托树脂的挠曲强度．用双因素方差分析和多重比较进行统计学处理。结果两种基托树脂的挠曲强度具有显著差异（P〈0.01），不同聚合方法间基托树脂的挠曲强度除电热法与一组水浴方法存在显著差异外．其余组间无显著差异。结论基托树脂的挠曲强度和材料的性能有关，不同聚合方法对基托树脂的挠曲强度没有显著影响。     

丙烯酸酯类义齿基托材料的研究进展

本文介绍了使用新型热聚合器、树脂上光剂、化学清洁剂改善热固化型丙烯酸酯类义齿基托表面光洁度和在基托材料中加入抑菌剂以减少基托表面细菌粘附的方法。在基托中加入玻璃纤维、超高分子量聚乙烯纤维等提高基托机械强度的材料研究新进展。     

纳米(PMMA/蒙托土)义齿基托复合材料力学性能的研究

目的:研究蒙托土对聚甲基丙烯酸甲酯(PMMA)义齿基托力学性能的改善。方法:将有机蒙托土按2.64%、3.89%、5.56%、6.92%的质量比加入聚甲基丙烯酸甲酯(PMMA)粉中,制成不同浓度的纳米(PMMA/蒙托土)义齿基托复合材料,对各组的挠曲弹性模量、挠曲强度进行检测,并对结果进行统计学分析。结果:添加蒙托土为2.64%、3.89%(质量比)的纳米(PMMA/蒙托土)义齿基托与普通PMMA义齿基托相比,挠曲弹性模量有所提高(P<0.05),挠曲强度没有显著性差异(P>0.05)。添加蒙托土为5.56%(质量比)的纳米(PMMA/蒙托土)义齿基托与普通PMMA义齿基托相比,挠曲弹性模量、挠曲强度均没有显著性差异(P>0.05)。添加蒙托土为6.92%(质量比)的纳米(PMMA/蒙托土)义齿基托与普通PMMA义齿基托相比,挠曲弹性模量没有显著性差异(P>0.05),挠曲强度下降(P<0.05)。结论:在聚甲基丙烯酸甲酯义齿基托中添加一定质量比有机蒙托土在不影响其挠曲强度的条件下可以改善其挠曲弹性模量。     

纳米义齿基托树脂的制备及挠曲性能的研究

目的在聚甲基丙烯酸甲酯粉（PMMA）中添加有机改性的蒙脱土制备纳米义齿基托树脂,以增强义齿基托树脂的挠曲性能。方法将蒙脱土经十六烷基三甲基溴化铵改性,形成有机化改性的蒙脱土,将其加入牙托粉中形成混和粉,混和粉与热凝牙托水调和后经加热固化形成纳米义齿基托树脂。用X射-线衍射（XRD）和透射电子显微镜（TEM）表征了固化后材料的结构,用三点挠曲试验测量固化后材料的挠曲强度和挠曲弹性模量。用一维方差分析法评价有机化蒙脱土的量对挠曲强度的挠曲弹性模量的影响。结果 XRD、TEM证实当蒙脱土在混合粉中的量为3%和5%时,蒙脱土在PMMA基质中形成部份剥离和插层结构;当蒙脱土在混合粉中的量为3%时,挠曲强度达最大,进一步增加蒙脱土的量,材料的挠曲强度降低。当混和粉中有机蒙脱土的量在1%~10%时,挠曲弹性模量随有机蒙脱土的量增加而增加。一维方差分析表明当混和粉中有机蒙脱土的量为3%时,实验组的挠曲强度与挠曲弹性模量均存在显著性差异（n=5,P〈0.05）。结论牙托粉中蒙脱土的量对义齿基托树脂的挠曲性能有显著性影响。     

纤维增强义齿基托树脂的应用研究

纤维增强义齿基托树脂作为提高义齿基托材料机械性能的一种技术,它所采用的增强纤维有玻璃纤维,碳纤维,芳纶纤维及超高模量聚乙烯纤维。本文通过对纤维增强义齿基托树脂有关文献的目的认为纤维的含量,纤维的埋入方式,纤维的表面处理等因素,均影响纤维增强义齿基托材料的机械性能。     

纤维增强义齿基托树脂的应用研究

纤维增强义齿基托树脂作为提高义齿基托材料机械性能的一种技术,它所采用的增强纤维有玻璃纤维、碳纤维、芳纶纤维及超高模量聚乙烯纤维。本文通过对纤维增强义齿基托树脂有关文献的回顾,认为纤维的含量、纤维的埋入方式、纤维的表面处理等因素,均影响纤维增强义齿基托材料的机械性能。     

义齿基托材料抗折强度的实验研究

本文选用临床常用的基托材料，制成试件。通过基托材料抗折强度的测试，对不同的基托进行了抗折强度，挠曲强度和弯曲破坏应力对比实验分析，证实了材料的抗折强度和挠曲强度与用其制作的义齿基托的抗折裂的相关性。义齿材料在外力征产生的机械性能与其折的关系，为临床口腔修复在基托的设计中提供依据。     

硅烷偶联剂的用量对PMMA/纳米ZrO2复合材料挠曲性能的影响

目的：研究硅烷偶联剂Z-6030的不同用量对聚甲基丙烯酸甲酯（PMMA）／纳米ZrO2复合材料挠曲强度的影响。方法：采用不同用量的硅烷偶联剂Z-6030，在丙酮溶液中对纳米ZrO2颗粒进行表面修饰，将经过表面修饰的纳米ZrO2颗粒按照3．0％的添加量，利用原位聚合生成法，与义齿基托树脂（聚甲基丙烯酸甲酯，PMMA）11型粉剂及液剂聚合生成分散良好的PMMA／纳米ZrO2义齿基托复合材料，参照IS01567：1999的标准，制作实验组的标准试件。用未添加纳米ZrO2颗粒及偶联剂的义齿基托树脂（聚甲基丙烯酸甲酯，PMMA）Ⅱ型粉剂及液剂制作普通基托组的标准试件。用添加未经表面修饰的纳米ZrO2颗粒的义齿基托树脂（聚甲基丙烯酸甲酯，PMMA）Ⅱ型粉剂及液剂制作对照组的标准试件。用三点弯曲试验测试材料的挠曲强度，采用SAS6．12软件包对结果进行单因素方差分析。结果：硅烷偶联剂Z-6030的用量为3．5％组的挠曲强度最大，与普通基托组、对照组、2．0％组、4．0％组、4．5％组、5．0％组有显著性差异（P〈0．05），0．5％组、1．0％组、1．5％组、2．5％组、3．0％组、3．5％组各组间的挠曲强度差异无统计学意义（P〉0．05）。0．5％组、1．0％组、1．5％组、2．0％组、2．5％组、3．0％组、4．0％组、4．5％组、5．0％组、普通基托组及对照组各组之间的挠曲强度的差异无统计学意义（P〉0．05）。结论：适当用量的硅烷偶联剂Z-6030可以提高PMMA／纳米ZrO2义齿基托复合材料的挠曲强度，硅烷偶联剂Z-6030的最佳用量为纳米ZrO2颗粒质量的3．5％。     

微波能固化义齿基托材料的实验性研究

目的 了解微波能加热处理义齿基托材料的力学性能和收缩变化。方法 采用微波能和水浴责任中方法加热固化义齿基托树脂。进行挠曲强度、硬度和收缩率的对比分析。结果 微波能固化的基托材料的力学性能与水溶法相比无显著性差异。但具有更好的尺寸精确性。结论 微波能是一种良好的固化义齿基托材料的热源。     

玻璃纤维增强复合树脂在总义齿基托中的应用

目的：增强总义齿基托的机械性能，提高总义齿的基托抗折裂能力。方法：对E－玻璃纤维用KH－550处理剂进行表面处理后，加入总义齿基托中，制成玻璃纤维增强复合树脂。结果：经过1年的临床观察后复诊，没有发现裂纹。结论：玻璃纤维增强得合树脂可以有效地增强总义齿基托的机械性能。     

An In-Vitro Evaluation of the Flexural Strength of Heat-Polymerized Poly (Methyl Methacrylate) Denture Resin Reinforced with Fibers

Fracture strength of denture base resins is of great concern and many approaches have been made to improve the fracture resistance of acrylic resin dentures by strengthening them. Purpose of the study was to assess the effect of a Novel pre-impregnated glass fiber reinforcement system and nylon fiber reinforcement on the flexural strength of conventional heat-polymerized poly(methylmethacrylate) [PMMA] denture resin under dry and wet storage conditions. Forty specimens of standard dimensions were prepared for each of the four experimental groups; unreinforced conventional acrylic resin and the same reinforced with unidirectional Stick (S) glass fibers, woven Stick Net (SN) glass fibers and nylon fibers. Each group was further subdivided into two groups of 20 specimens each on the basis of storage conditions (dry and wet). All 160 specimens were then subjected to a 3-point bending test and flexural strength was calculated. Statistical analysis was carried out using student t test and 1-way analysis of variance (ANOVA). Stick and Stick Net glass fiber reinforcements enhanced the flexural strength of conventional heat-cured PMMA denture resin. Specimens reinforced with Stick glass fibers exhibited highest flexural strength followed by those reinforced with Stick Net glass fibers. Nylon fiber reinforcement decreased the flexural strength of acrylic resin. All the specimens in the four groups stored under wet conditions showed decrease in flexural strength in comparison to those stored in dry conditions. The reinforcement of denture base resin with pre-impregnated glass fibers may be a useful means of strengthening denture bases. Use of nylon as a reinforcement fiber is not desirable as it decreased the flexural strength of acrylic resin.     

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.     

A Review of Fiber-Reinforced Denture Base Resins

Purpose One method of reinforcing denture base material is to use fiber composite reinforcement. Different types of fibers, such as glass (GF), carbon/graphite, aramid, and ultrahigh-modulus polyethylene (UHMP) fibers have been tested for this purpose. Materials and Methods This article reviews the studies conducted on the fiber-reinforced denture base resin systems. Results The literature has reported that the fiber concentration and its adhesion to polymer matrix influences the transverse strength of the fiber composite. The highest transverse strength value (265 MPa) with polymethyl methacrylate (PMMA) was obtained by incorporating 58 wt% GF into the resin. UHMP fibers incorporated into PMMA resin yielded the highest impact strength value (134 kJm^-2) of the fiber-PMMA composites. Conclusions Despite the improved mechanical properties of fiber-reinforced denture materials, further research is required to show the clinical usefulness of the fiber reinforcement.     

Effect of five woven fiber reinforcements on the impact and transverse strength of a denture base resin

STATEMENT OF PROBLEM: Fracture strength of denture base resins is of great concern, and many approaches have been used to strengthen acrylic resin dentures. PURPOSE: This study measured the effect of 5 fiber strengtheners on the fracture resistance of denture base acrylic resin material. Impact strength, transverse strength, deflection, and elasticity modulus values of a heat-polymerized denture base resin (Trevalon), reinforced with glass, carbon, thin Kevlar, thick Kevlar, and polyethylene fibers in woven form were studied. MATERIAL AND METHODS: One hundred acrylic resin test specimens reinforced with woven fibers were fabricated. The control group consisted of 20 specimens with no fiber reinforcement. For the impact strength test, a Charpy-type impact tester was used. Transverse strength was assessed with a 3-point bending test by using a screw-driven mechanical testing machine. Ten specimens were used for each test. RESULTS: The highest impact test values were produced by polyethylene-reinforced group, and the lowest values were obtained from specimens containing no fibers. There were significant differences among the test groups, but no significant differences in transverse strength were found. The lowest transverse strength values were obtained for specimens strengthened with polyethylene fibers, which also insignificantly decreased transverse strength of the acrylic resin. CONCLUSION: The impact strength of denture base acrylic resins was increased with fibers in woven form. Tested fibers did not have a significant effect on the transverse strengths.     

The static strength and modulus of fiber reinforced denture base polymer.

OBJECTIVES: Partial fiber reinforcements have been employed to strengthen dentures both during repair and in the manufacturing process. The reinforcing fibers can be evenly distributed in the denture base polymer or alternatively fiber-rich phase in the denture base polymer can form a separate structure. The aim of this study was to determinate static three-point flexural strength and modulus of denture base polymer that had been reinforced with different fiber reinforcements. METHODS: The test specimens (3 x 5 x 50 mm) were made of auto-polymerized denture base polymer and reinforced with different fiber reinforcements. The test groups were: (A) no fibers; (B) non-impregnated polyethylene fibers; (C) light-polymerized monomer impregnated glass fibers; (D) porous polymer preimpregnated glass fibers and (E) light-polymerized monomer-polymer impregnated glass fibers. The fibers were oriented parallel to the long axis of the specimen and embedded into the denture base resin on the compression side (n=7) or tension side (n=7). Dry specimens were tested with three-point static flexural strength test set-up at crosshead speed of 5 mm/min. RESULTS: The statistical analysis by two-way analysis of variance showed that the brand and the location of the fiber reinforcements significantly influenced the flexural strength (p<0.0001). However, the location of the fiber reinforcements did not influence the flexural modulus (p<0.722). SIGNIFICANCE: The results suggest that impregnated and preimpregnated fibers reinforce denture base polymer more than non-impregnated fibers. Fiber reinforcements placed on the tensile side resulted in considerably higher flexural strength and flexural modulus values compared with same quantity of fibers placed on the compression side.     

Evaluation of flexural resistance of a denture base acrylic resin reinforced with glass fiber and with composite resin

The objective of this study was to evaluate the flexural strength of denture base resin reinforced with glass fibers and with a laboratorial composite resin. Group G1 was formed with specimens made of acrylic resin. Group G2 was formed with the same acrylic resin but reinforced with a glass-fiber system, and G3 was reinforced with the composite resin. A flexural strength test was performed in all groups (n=10). The mean value for the G1 was 86.70 MPa +/- 6.48, for G2 it was 86.60 MPa +/- 15.01 and for G3 it was 108.90 + 11.03. The addition of glass fiber did not increase the flexural strength however the use of a resin-based composite produced significant reinforcement.     

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.     

Reinforcement of denture base resin with short vegetable fiber

Objectives

Short ramie fibers were selected to investigate the effect of fiber length and volume fraction on the flexural properties of ramie fiber reinforced denture base PMMA. With the aid of measured interfacial shear strength and theoretical prediction values, experimental results were well interpreted.

Methods

Interfacial properties between denture base PMMA and ramie fibers were evaluated by single fiber pull-out test. Then, chopped ramie fibers were pre-stirred with PMMA powder by a mechanical blender and then mixed with MMA liquid to fabricate composites. Two crucial influencing factors, fiber volume fraction and fiber length, were studied to clarify their effects on flexural properties of composites.

Results

With 1.5 mm fibers addition, flexural modulus of denture base PMMA rose from 2.50 to 3.46 GPa with 10 vol.% fibers, while flexural strength declined steadily with increment of fiber content. If fiber length was 3.0 mm, the modulus showed a growth to 3.5 GPa at 4 vol.% fiber content followed by a drop to 3.00 GPa at 10 vol.%, whereas fluctuation in strength was experienced. Experimental results were discussed by comparison with two theoretical models.

Significance

Short ramie fiber reinforced denture base PMMA had higher flexural modulus than neat resin, while strength was lowered due to the weak interfacial adhesion. The potential of vegetable fibers as reinforcing agents for denture base should be further investigated by strengthening the interface between cellulose and denture base PMMA.     

Flexural properties of glass fibre reinforced acrylic resin polymers

BACKGROUND: In recent years, glass fibres have been used to strengthen denture base resins. A major difficulty in using reinforcing fibres with multiphase acrylic resins, such as powder liquid resins, is inadequate impregnation of the fibres with the resin. METHODS: This investigation examined the reinforcing effect of glass fibres on the fracture resistance and flexural strength of acrylic denture base resins. Eighty identical specimens were formed in specially designed moulds in accordance with the manufacturer's recommendations. The four experimental groups were prepared and these consisted of conventional acrylic resin and the same resin reinforced with glass fibres. Ten specimens were fabricated in a standardized fashion for each experimental group. Flexural strength was tested using a 3-point universal testing machine. RESULTS: In this study, statistically significant differences were found in the flexural strength of the specimens (P < 0.05). The injection-moulded, fibre-reinforced group had significantly lower flexural strength than the injection-moulded group (P < 0.001), strength than the microwave-moulded, fibre-reinforced group (P < 0.001), and the microwave-moulded, fibre-reinforced group had lower flexural strength than the microwave-moulded group. The fracture resistance was significantly higher in the injection-moulded, fibre-reinforced group than in the injection-moulded group (P < 0.05), and the fracture resistance was significantly higher in the microwave-moulded, fibre-reinforced group than in the microwave-moulded group. CONCLUSION: Within the limitations of this study, the flexural strength of heat-polymerized PMMA denture resin was improved after reinforcement with glass fibres. It may be possible to apply these results to distal extension partial and complete denture bases.     

Flexural properties and impact strength of denture base polymer reinforced with woven glass fibers.

OBJECTIVES: The present investigation was undertaken to determine the reinforcing effect of woven glass fibers on deflection, flexural strength, flexural modulus and impact strength of acrylic denture base polymer. METHODS: Three silanized or unsilanized woven glass fibers were used. Specimens were made by heating the denture cure resin dough containing glass fibers, which were sheathed in the dough. Specimens with four different thicknesses and of five different types were made, incorporating the glass fiber. Three-point flexural test and flywheel type impact test were employed to determine the flexural properties and impact strength. RESULTS: When specimens contained unsilanized glass fiber, the flexural strength in specimens of 1 and 2 mm thickness and the impact strength in specimens of 2 mm thickness were higher than those of specimens without glass fiber (p < 0.01). On the contrary, the flexural strength and deflection in specimens reinforced with silanized glass fiber of 1 mm thickness were significantly higher (p < 0.01, p < 0.05) than those of unreinforced specimens. Further, the impact strength in specimens reinforced with silanized glass fiber of 2 mm thickness was significantly higher (p < 0.01) than that of unreinforced specimens. Statistically significant differences were found in the flexural strength (p < 0.05) and in the impact strength (p < 0.01) when specimens of 4 mm thickness were reinforced with two or three unsilanized glass fibers. SIGNIFICANCE: The reinforcement with glass fiber was effective in thin specimens, and the reinforcing effect increased with the increase of the number of glass fibers in the case of thick specimens.