甲基丙烯酸偶联二氧化钛/PMMA基托树脂的机械性能

目的研究甲基丙烯酸偶联二氧化钛对树脂基托材料的机械性能的影响。方法按质量比2%、4%、6%及偶联剂有无添加在2种树脂基托材料中,检测各组试件的弯曲强度、弯曲弹性模量、挠度和冲击强度,并用扫描电镜观察表面结构的差异,分析添加量以及偶联剂对树脂基托材料机械性能的影响。采用SPSS12.0软件对数据进行统计学处理。结果弯曲强度和冲击强度随着二氧化钛添加量增加而下降,偶联剂能减缓下降量,偶联剂对弯曲弹性模量和挠度有显著影响(P<0.05)。日进MTi4%的弯曲强度(154.22Mpa)、冲击强度(12.50kJ/m2)和弯曲弹性模量(3643.72Mpa)分别显著大于日进TiO24%(P<0.05)。结论二氧化钛会降低基托树脂的机械性能,甲基丙烯酸能减缓其下降幅度。     

不同类型义齿清洁剂对热凝基托树脂物理机械性能的影响

目的：观察不同类型义齿清洁剂对热凝基托树脂物理机械性能的影响。方法：将同样规格的热凝基托树脂试件,按使用说明分别浸泡在 Polident 清洁片或 Steradent 清洁片或0．5％次氯酸钠溶液和蒸馏水中60 h,处理后的试件在万能材料试验机和表面粗糙度测试仪上分别测其弯曲强度、弹性模量（n ＝10）和表面粗糙度（n ＝10）。结果：Polident、Steradent 对热凝基托树脂的弯曲强度和弹性模量的影响与蒸馏水组相比差异无统计学意义（P ＞0．05）,0．5％次氯酸钠组的弯曲强度和弹性模量小于其他组（P ＜0．05）;热凝基托树脂粗糙度4组之间差异无统计学意义（P ＞0．05）。结论：Polident、Steradent 均不影响热凝基托树脂的物理机械性能,0．5％次氯酸钠对热凝基托树脂的粗糙度无影响,而使其弯曲强度及弹性模量有所降低。     

注塑基托树脂力学性能的检测

目的：对Vertex注塑基托树脂的力学性能进行研究,为临床开展注塑技术提供理论依据。方法：分实验对照两组,实验组为注塑基托树脂,对照组为临床常用热凝基托树脂,按照2种基托树脂的操作步骤要求进行试样制备,对不同基托树脂的试样在材料试验机上测定其冲击强度、弯曲强度、弹性模量和布氏硬度,并对断面进行电子显微分析。结果：注塑基托树脂和热凝基托树脂的冲击强度分别为6.01±0.50KJ/mm^3,7.35±0.93KJ/mm^3,（P〉0.05）,弯曲强度为104.44±3.07MPa,90.19±6.88MPa,（P〈0.05）,弹性模量为2.1±0.2GPa,2.4±0.1Gpa,（P〉0.05）,布氏硬度为12.17±0.93kg/mm^2,19.57±2.89kg/mm^2,（P〈0.05）;两种基托树脂的微观结构有明显不同,注塑基托树脂内部分布着许多粒径颗粒。结论：Vertex注塑基托树脂不仅具有热凝基托树脂的抗冲击能力,还具有良好的抗弯性能,韧性佳,是一种比较好的义齿基托树脂。     

氧化锌晶须填料对义齿基托树脂力学性能的影响

目的：研究添加氧化锌晶须对基托树脂力学性能的影响。方法：将氧化锌晶须按不同的质量百分比加人基托粉中,分为空白对照组、1％、3％、5％、7％等5组。根据ISO标准测试各组的力学性能,并对试样断面进行扫描电镜观察。结果：随着氧化锌晶须用量的增加,复合材料的弯曲强度、弯曲弹性模量、显微维氏硬度呈先升后降的趋势。当氧化锌晶须用量为5％时,以上指标测得值最高,分别为（109．00±2．70）MPa、（3645．30±198．68）MPa、（20．57±0．85）kg／mm^2,树脂基托较对照组弯曲强度提高18．29％、弯曲弹性模量提高16．07％、显微维氏硬度提高29．94％。结论：氧化锌晶须填料显著增强了基托树脂的力学性能。     

四种加工方式对基托树脂力学性能的影响

目的 探讨不同混合和热加工方式对义齿基托树脂力学性能的影响,探讨捏炼混合+电烤箱加热的固化方式可否提高基托树脂的力学性能.方法 制作4组基托树脂试件,第1组:常规混合+水浴加热;第2组:捏炼混合+水浴加热;第3组:常规混合+电烤箱加热;第4组:捏炼混合+电烤箱加热.测定树脂的表面硬度、弯曲强度和弯曲模量、冲击强度.结果 第1～4组试件表面硬度分别为19.4、21.2、22.3、23.2 N/mm2,弯曲强度分别为58.58、63.32、66.73、63.76 MPa,冲击强度分别为1.42、1.53、1.77、1.78 KJ/m2,弯曲模量分别为2311.38、2417.82、2566.36、2400.37 MPa.结论 与常规混合+水浴加热方式相比,捏炼混合+电烤箱加热方式制作的树脂有较高的表面硬度和冲击强度,综合力学性能较佳.     

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。     

改性纳米氧化铈对义齿树脂基托机械性能的影响

目的:研究经硬脂酸改性后的纳米CeO₂对义齿树脂基托机械性能的影响。方法:将改性纳米颗粒按照质量比分别为1%、2%、3%、4%和5%的添加量添加到义齿基托材料(PMMA)的单体中,制成不同浓度的纳米齿复合材料,制成标准试件。对每组试件冲击强度,弯曲强度等指标进行检测,并与未添加纳米颗粒组比较,将最终数据进行统计分析。结果:经硬脂酸改性后的纳米氧化铈能够提高树脂基托的机械性能,所测试指标都呈现先增大后减小的趋势。其中添加比例为3%时纳米复合材料的综合性能达到最佳状态,其冲击强度、弯曲强度和弯曲模量分别为(4.186±0.149) J/cm²、(88.865±2.345) MPa和(1.539±0.096) GPa(P<0.05)。结论:在义齿基托材料单体中加入不同浓度的纳米氧化铈颗粒可以提高传统义齿基托的冲击强度,弯曲强度等机械性能,从而可以获得品质优良的纳米义齿复合材料。     

单氟磷酸钠对口腔义齿基托树脂材料力学性能的影响

目的：将单氟磷酸钠按一定比例添加到聚甲基丙烯酸甲酯义齿基托材料中,探讨不同用量的单氟磷酸钠加入可摘局部义齿的基托树脂后,对其力学性能的影响。方法：将单氟磷酸钠0、10％、15％、20％、25％5种不同质量分数的热凝和自凝树脂制备成大小为60mm×8mm×4mm的含氟树脂块共180个并按各种质量分数随机分为3组,分别进行冲击强度、抗弯曲强度、50牛顿力作用下横向弯曲值3项指标测试。记录结果后进行计算和统计分析。结果：单氟磷酸钠质量分数为20％以下各组抗弯曲强度、冲击强度与对照组无显著差异（P〉0．05）,50牛顿力作用下平均横向弯曲值在国家标准内;单氟磷酸钠质量分数为25％时抗弯曲强度、冲击强度与对照组有显著差异（P〈0．05）,50牛顿力作用下平均横向弯曲值超出国家标准外。结论：将质量分数0-20％的单氟磷酸钠添加到聚甲基丙烯酸甲酯义齿基托材料中不会影响其力学性能,当单氟磷酸钠质量分数超过25％时将明显影响基托材料的力学性能。     

热固化基托树脂外源性着色的体外研究

目的评价5种食物、药物对热固化基托树脂着色的程度。方法制作90块热固化基托树脂试件,随机分为6组,分别浸泡于蒸馏水(对照)、绿茶、橙汁、漱口水、药酒和黄连水中,用电子比色仪测量树脂浸泡前及浸泡1、2、3、4周后的颜色,得到L*、a*、b*值,计算各时间点与浸泡前的色差ΔE,进行统计学分析。结果除对照组外,5组实验组试件的ΔE值(颜色改变)均随浸泡时间延长而增大;不同浸泡液中试件的ΔE值有显著性差异,其大小顺序为:黄连水>漱口水>绿茶>药酒>橙汁。结论绿茶、橙汁、漱口水、药酒和黄连水均可导致热固化基托树脂表面着色,尤以黄连水着色最重。且随着时间延长,基托树脂表面着色加重。     

添加纳米二氧化钛的树脂基托性能测试

目的:将纳米二氧化钛抗菌剂添加到义齿基托后具有一定的抗菌性,为进一步观察纳米二氧化钛抗菌剂对树脂基托机械性能的影响,本实验将检测弯曲强度、弹性模量、吸水率、溶解率,探讨其最佳添加比例。方法:按照1%、3%、5%的添加比例将纳米二氧化钛抗菌剂与基托粉混合,通过测量混合不同比例抗菌剂的树脂组、空白对照组的弯曲强度和弹性模量来检测抗菌剂对树脂机械性能的影响;采用称重方法检测树脂的吸水值、溶解值,使用方差分析、t检验对数据进行分析。结果:0%、1%、3%、5%添加量的树脂弯曲强度分别为:(99.2±13.1)MPa、(106.07±12)MPa、(134.67±22)MPa、(114.40±5.7)MPa;弹性模量分别为:(1.16±0.10)Gpa、(1.22±0.26)Gpa、(1.38±0.26)Gpa、(1.32±0.21)Gpa;吸水值为:26μg/mm3、28μg/mm3、25μg/mm3、30μg/mm3。溶解值为:1.4μg/mm3、1.5μg/mm3、1.1μg/mm3、1.2μg/mm3。统计分析结果显示(P<0.05)。结论:纳米二氧化钛无机抗菌剂对树脂的机械性能有显著影响,其中3%纳米二氧化钛无机抗菌剂添加量的树脂的机械性能最高。     

Flexural properties of denture base resins subjected to long-term water immersion

Abstract

Objective. The aim of this study was to investigate the flexural properties of denture base resins subjected to long-term water immersion. Materials and methods. Four denture base resins (one conventional heat-processed, one microwave energy-processed and two pour-type autopolymerizing) were selected for this study. The specimens of each denture base material tested were fabricated according to the manufacturers' instructions (n = 10). The flexural properties of the denture base resins were measured according to ISO 20795-1. The ultimate flexural strength, the flexural strength at the proportional limit and the elastic modulus of the specimens were evaluated. Results. The ultimate flexural strengths of the heat-processed resin and the two pour-type autopolymerizing resins significantly decreased after 6 months water immersion. The flexural strength at the proportional limit of the heat-processed resin significantly decreased after 6 months water immersion, but the microwave energy-processed denture base resin and two pour-type autopolymerizing resins did not change after 6 months water immersion. The elastic moduli of the heat-processed resin, the microwave energy-processed denture base resin and one pour-type autopolymerizing resin significantly increased after 6 months water immersion. Conclusion. The flexural properties of denture base resins significantly changed after long-term water immersion.     

Transverse strength and acoustic emission characteristics of commercial denture base resins

Transverse strength and acoustic emission (AE) characteristics were measured by the transverse test in deionized water at 37 degrees C on commercial denture base resins (five heat-cured type resins and one polysulfone). Difference in flexural property of five heat-cured denture base resins was not shown from the transverse deflection according to JIS, but high toughness of polysulfone was recognized in transverse deflection, flexural strength, flexural modulus, flexural rigidity, flexural proof stress, and fracture energy. The five heat-cured denture base resins showed a low AE activity, but the polysulfone resin high AE activity. Significant rates of AE for polysulfone were detected at a kgf of approximately 50-60% the maximum load. The presence of Kaiser effect in its cycle transverse test was confirmed.     

义齿清洁剂对热固化型基托树脂物理及机械性能的影响

目的 评价5种义齿清洁剂对热固化型基托树脂颜色稳定性、表面粗糙度、弯曲强度的影响。方法 热固化型基托树脂试样浸泡于保丽净、澳多—C、Protefix、0.2%葡萄糖酸氯己定、雅克菱义齿清洁剂以及蒸馏水中,后测量试样颜色的改变(ΔE)、粗糙度值、弯曲强度。结果 0.2%葡萄糖酸氯己定、雅克菱义齿清洁剂的颜色改变较对照组显著较大;将ΔE值用NBS（美国国家标准局）单位来表示,所有组对应的人色差感觉程度均为感觉轻微。对于表面粗糙度和弯曲强度,不同浸泡处理组间无统计学差异。结论 热固化型基托树脂使用义齿清洁剂180 d后,0.2%葡萄糖酸氯己定、雅克菱浸泡后颜色稳定性较差,但为临床可接受。保丽净、澳多—C、Protefix对材料均无影响。     

Effects of chemical disinfectants on the transverse strength of denture base acrylic resins

The disinfection of dental prostheses by immersion in a chemical solution should be capable of rapid inactivation of pathogenic microorganisms, without causing any adverse effect on the denture base resins. This study evaluated the effect of disinfection immersion on the transverse strength of two heat-cured resins. The denture base resins (Lucitone 550 and QC 20) were polymerized according to the manufacturers' instructions. After polymerization, the specimens were polished, and then stored in water at 37 degrees C for 50 +/- 2 h prior immersion in one of the following solutions for 10 min: 4% chlorhexidine, 1% sodium hypochlorite and 3.78% sodium perborate. The specimens were submitted to disinfection twice, simulating when dentures come from the patient and before being returned to the patient. Ten specimens were made for each group. The transverse strength was evaluated by a 3-point bend test. The flexural strength of the two denture base acrylic resins evaluated remained unaffected after immersion in the three solutions evaluated. In general, the QC 20 resin specimens exhibited lower transverse strength than the Lucitone 550 resin specimens, regardless of immersion solutions.     

Effects of antibacterial coating on monomer exudation and the mechanical properties of denture base resins

Statement of problem

Denture base resin may be exposed to different conditions for long periods, resulting in the loss of monomer by exudation and a decrease in mechanical properties.

INFLUENCE OF INCORPORATION OF FLUOROALKYL METHACRYLATES ON ROUGHNESS AND FLEXURAL STRENGTH OF A DENTURE BASE ACRYLIC RESIN

Fluorinated denture base acrylic resins can present more stable physical properties when compared with conventional polymers. This study evaluated the incorporation of a fluoroalkyl methacrylate (FMA) mixture in a denture base material and its effect on roughness and flexural strength. A swelling behavior assessment of acrylic resin specimens (n=3, per substance) after 12 h of FMA or methyl methacrylate (MMA) immersion was conducted to determine the solvent properties. Rectangular specimens (n=30) were allocated to three groups, according to the concentration of FMA substituted into the monomer component of a heat-polymerized acrylic resin (Lucitone 550), as follows: 0% (control), 10% and 20% (v/v). Acrylic resin mixed with concentrations of 25% or more did not reach the dough stage and was not viable. The surface roughness and flexural strength of the specimens were tested. Variables were analyzed by ANOVA and Tukey''s test (α=0.05). Immersion in FMA produced negligible swelling, and MMA produced obvious swelling and dissolution of the specimens. Surface roughness at concentrations of 0%, 10% and 20% were: 0.25 ± 0.04, 0.24 ± 0.04, 0.22 ± 0.03 μm (F=1.78; p=0.189, not significant). Significant differences were found for flexural strength (F=15.92; p<0.001) and modulus of elasticity (F=7.67; p=0.002), with the following results: 96 ± 6, 82 ± 5, 84 ± 6 MPa, and 2,717 ± 79, 2,558 ± 128, 2574 ± 87 MPa, respectively. The solvent properties of FMA against acrylic resin are weak, which would explain why concentrations over 20% were not viable. Surface changes were not detected after the incorporation of FMA in the denture base acrylic resin tested. The addition of FMA into denture base resin may lower the flexural strength and modulus of elasticity, regardless of the tested concentration.     

Effect of cavity preparation on the flexural strengths of acrylic resin repairs

Objective

To investigate the effect of cavity preparation on the flexural strength of heat-curing denture resin when repaired with an auto-curing resin.

Material and methods

Ninety-six rectangular specimens (64x10x2.5 mm) prepared from heat-curing denture base resin (Meliodent) were randomly divided into four groups before repair. One group was left intact as control. Each repair specimen was sectioned into two; one group was repaired using the conventional repair method (Group 1). Two groups had an additional transverse cavity (2x3.5x21.5 mm) prepared prior to the repair; one repaired with (Group 2) and one without glass-fiber reinforcement (Group 3). A three-point flexural bending test according to the ISO 1567:1999 specification⁸ for denture base polymers was carried out on all groups after 1, 7 and 30 days of water immersion. Statistical analysis was carried out using two-way ANOVA, Kruskal Wallis and post-hoc Mann Whitney tests.

Results

The highest flexural strength was observed in the control group. Control and conventional repairs group (Group 1) showed reduction in the flexural strength 30 days after water immersion. No significant change in the strength was observed for Groups 2 and 3 where the repair joints were similarly prepared with additional transverse cavity.

Conclusion

Repaired specimens showed lower flexural strength values than intact heat-curing resin. Cavity preparation had no significant effect on the flexural strength of repair with water immersion.     

The effect of glutaraldehyde base disinfectants on denture base resins

The effect of two alkaline glutaraldehyde base disinfectants on a heat-cured denture base resin was evaluated by the flexural strength, the repair flexural strength, and the surface morphology of the material that had been immersed up to 12 hours in the disinfecting solutions. The flexural strength of the material was not significantly affected by either disinfectant. The disinfectant with phenolic buffer caused surface pitting of the material after 10 minutes of immersion, and softening and swelling of the surface after 2 hours of immersion. No apparent surface change was observed with the regular alkaline formulation, however. Between the two repair resins, the autopolymerized resin yielded greater repair flexural strength than the light-cured repair resin. However, the repair flexural strength of autopolymerized resin seemed to be influenced by either disinfecting solution whereas the light-cured repair resin was not affected.