飞行时间质谱仪监测甲基丙烯酸甲酯释放初探

目的 通过飞行时间质谱仪对自凝树脂聚合反应的全过程进行连续监测,动态分析甲基丙烯酸甲酯(methyl methacrylate,MMA)的变化趋势,以期为临床操作提供指导.方法 按生产厂家要求的比例将自凝义齿基托树脂粉剂2 g和液剂1 g调拌40 s后,即刻用飞行时间质谱仪连续监测MMA释放量,共监测5个样本.结果 MMA释放量在调拌后11 min时快速增加[(45.2±3.5)mg/L],13 min时达高峰[(228.9±22.6)mg/L];23 min时趋于稳定[(8.8±2.3)mg/L].结论 飞行时间质谱仪可连续监测自凝义齿基托树脂的聚合过程,精确地分析MMA释放量的变化趋势.结果 显示自凝义齿基托树脂聚合反应的MMA释放量变化较快.

Abstract：

Objective To analyze the amount and tendency of methyl methacrylate(MMA) released from autopolymerized denture base polymer (self-curing resin) during processing using time-of-flight mass spectrometer(TOF-MS). Methods Self-curing resin was mixed in the container using a ratio of 2 g of powder to 1 g of liquid in accordance with the manufacturer's instructions for 40 s as a specimen. The amount of MMA released from the specimen was continuously monitored and simultaneously recorded every minute by TOF-MS since immediately after mixing. A total of five specimens were monitored. Results The amount of MMA increased dramatically at 11 min[(45.2 ±3.5) mg/L] after mixing, and reached the highest level at 13 min[(228.9 ±22.6) mg/L], then become stable at 23 min[(8.8 ±2. 3) mg/L] after mixing. Conclusions The releasing tendency of MMA could be analyzed accurately with continuously monitoring during processing. The amount of MMA released from self-curing resin changed rapidly and the processing was complicated and changeful.     

自凝树脂聚合过程中其自身温度变化对甲基丙烯酸甲酯释放量的影响

目的：研究自凝义齿基托树脂（简称自凝树脂）在聚合过程中其自身温度的变化趋势、甲基丙烯酸甲酯（methyl methacrylate,简称MMA）释放量的变化趋势及二者的关系。方法：室温20℃,把自凝树脂粉2g和液1g混合,调拌40s后,立即用万用表测量样本中心温度,同时用飞行时间质谱仪连续监测MMA的释放量,待MMA释放量稳定后停止监测。结果：在自凝树脂聚合过程中样本温度和MMA释放量的变化趋势相似：监测开始,温度和MMA释放量变化不大,分别在7和11min后快速升高,11和13min达最高,之后逐渐下降,直至25和23min后趋于稳定。样本温度和MMA释放量的变化存在直线相关（P〈0.05）。结论：自凝树脂聚合过程中,MMA释放量随其本身温度的升高而增加,随温度的下降而减少。     

聚合方式对义齿基托树脂中残余甲基丙烯酸甲酯单体含量的影响

目的研究聚合方式对义齿基托树脂中残余甲基丙烯酸甲酯含量的影响。方法按照不同的聚合方式,将实验分为3组,每组制备3块试验样块.按照YY0270-2003规定的气相色谱法实验方法测试各组样品的甲基丙烯酸甲酯单体（MMA）含量。结果不同聚合方式得到的材料中MMA的百分含量明显不同,以微波聚合方式得到的基托材料残余单体含量最低。结论聚合方式对义齿基托材料残余单体含量具有显著影响。     

国内外几种自然色义齿基托树脂主要性能比较研究

本研究选择了具有代表性的Lucitone、Meliodent、Pigeon、HO—1、HO—2等5种自然色义齿基托树脂,对其抗弯、吸水性、溶解性等主要性能进行了对比研究。结果表明:牌号为Lucitone的基托树脂冲击强度最佳,其他性能,5种义齿基托树脂没有显著的差异。     

聚甲基丙烯酸甲酯义齿基托材料清洁抗菌研究进展

聚甲基丙烯酸甲酯是一种常用的义齿基托材料,由于自洁作用差,基托聚合物的溶出和固化时产生的微孔易在其表面形成菌斑、牙石的沉积。因此迫切需要应用较理想的方法清洁基托表面、提高基托自身的抗菌性。本文就义齿基托材料清洁抗菌机制及方法作一综述。     

两种基托材料制作的活动义齿疗效分析

目的　探讨弹性基托材料在牙列缺损修复中的应用。方法　为 2 76例牙列缺损患者用弹性基托材料制作各类隐形活动义齿 32 8件 ,随访 2年 ,对义齿的各种性能进行观察 ,并与甲基丙烯酸甲酯制作的活动义齿作配对比较。结果　两种基托材料所制成活动义齿优与良统计分析结果差异有显著性 (P <0 0 5 )。结论　隐形义齿具有美观、舒适、基托不折断、不变形、坚固耐用、制作方便等优点。     

聚甲基丙烯酸树脂义齿基托消毒的研究进展

活动义齿包括全口义齿的树脂基托在临床上广泛应用,基托与口腔黏膜紧密贴合,基托表面极易聚集病原菌,在义齿基托的制作调改以及日常戴用过程中对其消毒极为必要。现就义齿基托消毒的现状做一综述,为临床工作提供指导。     

有机蒙脱土增强的纳米义齿基托树脂中残留甲基丙烯酸甲酯含量的测定及分析

目的:研究纳米义齿基托树脂在使用有机蒙脱土(OMMT)增强义齿基托的机械性能后,材料中OMMT的含量对固化后材料中残留甲基丙烯酸甲酯(MMA)含量的影响,并确定合适的OMMT的混合比例,使固化后材料的机械性能得到较好提高的同时残留MMA含量也在可接受的范围内。同时对该固化材料在水中MMA的释放量进行测定。方法:材料中残留的MMA用丙酮进行抽提,材料在水中释放的MMA用氯仿萃取。抽提液和萃取液用气相色谱测定其中MMA的浓度。结果:OMMT的量对固化材料中残留MMA的量有显著性影响(P<0.05),随着固化材料中OMMT的量的增加,残留MMA的量也逐渐增加。当OMMT的混合比例为1wt%时,不仅材料的机械性能的到了较好提升,材料中的残留MMA的量也在YY0270-2003标准(最大2.2wt%)范围内。放置于37℃水中7d后,MMA的释放量随时间的增加趋于稳定;观察3周,MMA水中释放量小于用丙酮抽提时所测得的残留MMA量。结论:固化材料中MMA的含量随着OMMT含量的增加而增加。材料在水中的MMA释放量小于用丙酮抽提时所测得的MMA量。     

义齿塑料基托热压灌注成型新工艺—颜色稳定性的比较研究

目的：分析比较成型后的基托塑料可能发生的变色。方法：对不同粉、液比例灌注成型的基托塑料和常规模压成型的基托塑料，用分光测色仪观察颜色稳定性。结果：粉、液以２∶１体积比灌注成型的义齿基托，表面平整光滑，色调、饱和度与常规模压成型的义齿基托相同，而其表面可抛光性优于常规法。结论：２种方法成型的义齿基托对紫外线的敏感性无显著性差异。     

纳米载银树脂基托的体外抗菌效果

目的研究纳米载银树脂基托在体外对变形链球菌和白色念珠菌的抗菌效果。方法先测定纳米载银抗菌剂对变形链球菌和白色念珠菌的最小抑菌浓度,并以此为依据在聚甲基丙烯酸甲酯基托树脂粉中添加不同比例的抗菌剂,制成抗菌树脂基托,用贴膜法测定该树脂基托对变形链球菌和白色念珠菌的抗菌率。结果纳米载银抗菌剂对变形链球菌的最小抑菌浓度为0.1mg/ml,对白色念珠菌的最小抑菌浓度为1mg/ml。当添加抗菌剂的浓度分别为1、2、5、10mg/ml时,树脂基托对变形链球菌的抗菌率分别为67.4%、71.3%、99.0%、99.5%;对白色念珠菌的抗菌率分别为25.8%、54.8%、90.3%、93.0%。结论载银抗菌树脂基托在体外表现了一定的抗变形链球菌和抗白色念珠菌的效果,当树脂基托中抗菌剂的浓度达到5mg/ml时,抗菌效果满意。     

Release of methyl methacrylate from heat-cured and autopolymerized resins: cytotoxicity testing related to residual monomer

Three heat-cured and three autopolymerized acrylic denture bases with different mixing proportions and/or processing methods were investigated for the amount of residual monomer content and methyl methacrylate (MMA) released into saliva after incubation during the first and second 24 hours after processing. A corresponding range of concentrations of MMA was also used to test for cell cytotoxicity using a culture of human oral fibroblasts. The results showed that the amount of residual monomer was dependent not only on the type of polymerization but also on the amount of liquid in the mixture ratio and the processing method. The acrylic resin that had the lowest residual monomer also released the smallest amount of MMA but resins which have higher residual monomer may not necessarily release higher amounts of MMA. MMA, tested in the same range of concentration as the MMA found leached from acrylic resin in this study, was found to be toxic in the cell culture. Therefore, it is recommended that dentists attempt to reduce the amount of leachable substances before insertion of new dentures. In addition, it is recommended that dentists advise their patients not to wear newly made dentures overnight, as this may cause mucosal irritation from the potential accumulation of leachable substances.     

Effect of glass fibre reinforcement on residual methyl methacrylate content of denture base polymers

OBJECTIVES: Residual methyl methacrylate (MMA) content in unreinforced and in glass fibre reinforced, heat-polymerized (long- and short-term terminal boiled and conventionally) autopolymerized (at room temperature and in water at 60 degrees C) and microwave-polymerized (3min at 500W) denture base polymers after processing were compared. METHODS: Ten specimens were prepared for each curing cycle (five unreinforced and five reinforced) adding up to a total of 60. Residual MMA content was determined using high-performance liquid chromatography. Data were analysed with one-way ANOVA followed by Tukey HSD and Paired Samples tests. RESULTS: For unreinforced and reinforced groups; residual MMA content succesively ranked from lowest to highest in; long- and short-term terminal boiled heat-polymerized, microwave-polymerized, autopolymerized specimens processed in water at 60 degrees C and conventionally heat- and autopolymerized specimens processed at room temperature. Generally residual MMA was found more in glass fibre reinforced test groups than unreinforced groups. However, when reinforced residual MMA increased significantly in long- and short-term terminal boiled heat- (P<0.05) and microwave-polymerized test groups (P<0.01). CONCLUSIONS: Although this increase was significant, lowest residual MMA content was found succesively in reinforced long- and short-term terminal boiled heat-polymerized and microwave-polymerized like in unreinforced groups.     

Residual methyl methacrylate monomer, water sorption, and water solubility of hypoallergenic denture base materials

STATEMENT OF PROBLEM: Denture base materials have the potential to cause irritation and allergic reaction to the oral mucosa. Water sorption and water solubility of denture base resins affect dimensional behavior and denture stability. A correlation between residual monomer and water sorption exists. PURPOSE: This in vitro study compared the amount of residual monomer, quantity of water sorption, and solubility of 4 denture base materials purported to be hypoallergenic with those of a polymethyl methacrylate-based (PMMA) heat-polymerizing acrylic resin. MATERIAL AND METHODS: The denture base resins Sinomer (heat-polymerized, modified methacrylate), Polyan (thermoplastic, modified methacrylate), Promysan (thermoplastic, enterephthalate-based), and Microbase (microwave polymerized, polyurethane-based), which are purported to be hypoallergenic, and Paladon 65 (heat-polymerized, methacrylate, control group) were examined. Specimens of each material were tested for residual methyl methacrylate (MMA) monomer (% wt, n=3), amount of water sorption (microg/mm3, n=5) and water solubility (microg/mm3, n=5), according to ISO 1567:2000. The residual MMA monomer concentrations were determined by gas chromatography (GC). The data were analyzed with 1-way ANOVA and the Bonferroni-Dunn multiple comparisons post hoc analysis for each test variable (alpha=.05). RESULTS: Significantly lower residual MMA monomer was shown for Sinomer and Polyan compared to the PMMA control group (0.90 +/- 0.20% wt, P<.05). Sinomer contained 0.31% +/- 0.00% wt MMA monomer, and Polyan exhibited residual MMA monomer content of 0.44% +/- 0.01% wt. Promysan and Microbase did not contain detectable residual MMA. Water sorption of Promysan (16.21 +/- 0.96 microg/mm3) was significantly lower than Paladon 65 (23.04 +/- 3.13 microg/mm3, P<.0001), whereas water solubility of the hypoallergenic denture base materials (0.34-0.84 +/- 0.05-0.09 microg/mm3) was not significantly lower than the PMMA material (0.40 +/- 0.06 microg/mm3, P>.05). Except for Sinomer, the tested denture base resins passed the requirements of ISO 1567 regarding residual MMA monomer (<2.2% wt). Sinomer failed to comply with the requirements for residual MMA monomer because the manufacturer claimed that the material did not contain any MMA. The tested denture base materials fulfilled the requirements regarding water sorption (<32 microg/mm3) and solubility (<1.6 microg/mm3). CONCLUSION: The tested hypoallergenic denture base materials exhibited significantly lower residual monomer content than PMMA. Promysan and Microbase showed no detectable residual MMA.     

Leaching and cytotoxicity of formaldehyde and methyl methacrylate from acrylic resin denture base materials

Acrylic resin dentures have the potential to elicit irritation, inflammation, and an allergic response of the oral mucosa. Studies of substances leachable from acrylic resins, their cytotoxicity to cultured cells, and means of reducing their leaching were systematically conducted. Under in vivo and in vitro conditions, formaldehyde and methyl methacrylate were significantly leached into human saliva and saliva-substitute buffer, especially from autopolymerized resins. Both leachable substances showed cytotoxic potentials in the range of their leaching concentrations. Formaldehyde was cytotoxic at lower concentrations than methyl methacrylate. Preleaching in water reduced subsequent leaching of both formaldehyde and methyl methacrylate, and the amount of reduction depended on an increase in the preleaching temperatures. Immersion of acrylic resin dentures in hot water (50 °C) before insertion is recommended, especially for autopolymerized resins used either for rebasing or as denture base materials, to minimize the risk of adverse reactions in patients who wear acrylic resin dentures.     

Microwave energy polymerization of poly(methyl methacrylate) denture base resin

Several physical property tests were conducted to compare microwave energy and conventional hot water bath polymerization techniques. The two methods of polymerization produced similar dimensional accuracy in complete denture bases. No differences were found in transverse strength, Knoop hardness, density, and residual monomer content of resin test strips. Comparable strength was found between microwave-polymerized and autopolymerized repairs of resin test strips. No porosity was observed in complete or removable partial denture bases polymerized by either technique. The Knoop hardness of microwave-polymerized removable partial denture bases was found to be slightly lower near the metal framework.     

新型电热聚合法对义齿基托残余单体含量的影响

目的研究一种新型电热聚合法对义齿基托残余单体含量的影响,并与传统水浴法在用水耗电上做比较。方法选择两种常用热凝义齿基托树脂材料,分别采用传统水浴法和电热聚合法制作样本,测量每次聚合过程中所需的用水量和耗电量。用气相色谱仪进行各样本残余甲基丙烯酸单体(MMA)的检测和比较。结果各样本残余MMA含量都满足国家医药行业YY0270-2003标准要求,传统水浴法的残余MMA含量略低,差别有统计学意义(P<0.05)。传统水浴法制作义齿每次每型盒用水1.25L,耗电(0.53±0.02)kwh,电热聚合法不需用水,耗电(0.09±0.02)kwh,差别有统计学意义。结论电热聚合法所制作样本残余MMA含量符合相关标准,是一种高效、节能的义齿基托聚合方法。