不同类型牙本质粘接系统中单体Bis-GMA的析出动力学研究

目的:利用反相高效液相色谱法定量分析不同牙本质粘接体系中Bis-GMA随时间变化的析出量。方法:15个牙本质片(8 mm×8 mm×1 mm)根据选用的牙本质粘接剂随机分为Single Bond 2(SB)、Clearfil SE Bond(SEB)和Clearfil 3SBond(3SB)3组,分别按使用说明进行粘接操作后储存于37℃、75%的酒精中浸泡老化,于10 min、30 min、1 h、3 h、6 h、24h、48 h、72 h、7 d、14 d各取每个试件浸泡的老化液进行反相高效液相色谱议(HPLC)检测,对结果数据做单因素方差分析。结果:3种不同类型的粘接系统中均存在未聚合单体Bis-GMA的析出,且主要集中在操作完成后的24 h内,以最初10 min内的析出量最高,SEB组>3SB组>SB组(P<0.01)。结论:不同类型牙本质粘接系统内的单体Bis-GMA在75%的酒精中的析出动力学基本类似。     

氧化锆、纳米金刚石填料比例对核树脂颜色的影响

目的观察二氧化锆、纳米金刚石作为功能填料加入到自行合成的以钡玻璃粉为主填料的光固化牙科核树脂中,其核树脂颜色的变化。方法采用双酚A-甲基丙烯酸缩水甘油酯(Bis-GMA)和二甲基丙烯酸三甘醇酯(TEGDMA)为树脂基质,钡玻璃粉(BG)为主填料,选择不同比例的二氧化锆,纳米金刚石作为功能填料,采用原位聚合法生成光固化牙科核树脂,经万能材料试验机测试后,选择出挠曲强度达到国家YY1042和国际ISO4049标准的六组树脂,以ShofuShadeEye测色仪测量并分析其核树脂与63例人牙本质样本的色差。结果5组核树脂色度值位于63例天然牙牙本质色度值分布范围附近,核树脂与63例牙本质色度均值的色差为5.6～12.24之间。结论自行合成的核树脂与63例牙本质色度均值的色差在临床可接受的范围内,能满足临床用此核树脂美容修复牙体内部缺损的需要。     

氧化锆和纳米金刚石比例对核树脂挠曲强度的影响

目的 探讨二氧化锆、纳米金刚石比例对核树脂挠曲强度的影响.方法 采用双酚A-甲基丙烯酸缩水甘油酯(Bis-GMA)和二甲基丙烯酸三甘醇酯(TEGDMA)为树脂基质, 钡玻璃粉(BG)为主填料, 选择不同比例的微米或纳米级二氧化锆,纳米金刚石作为功能填料, 采用原位聚合法生成光固化牙科核树脂,万能材料试验机测定其挠曲强度.结果 含60wt%钡玻璃粉、0.2wt%纳米金刚石的树脂中,加入纳米级或微米级的二氧化锆含量分别为2wt%、3.5wt%、5wt%,3.5wt%相应核树脂挠曲强度最高;含70wt%钡玻璃粉、0.1wt%纳米金刚石的树脂中,加入40 nm的二氧化锆含量为0wt%、2wt%、3.5wt%、5wt%,2wt%质量百分比相应核树脂挠曲强度最高.结论 适当比例填料的核树脂挠曲强度能达到相应的国家标准及ISO标准的规定,能满足临床需要.     

光敏固化充填材料不磨牙修复牙组织缺损的初步观察

<正> 自1955年 Buonocore 研究了酸蚀釉质以增强树脂补牙材料与釉质的粘结力后,1968年 Roydhouse 首次将双酚 A-甲基丙烯酸缩水甘油酯(Bis-GMA)作为主体材料封闭点隙裂沟。1970年 Buonocore 尝试用光敏固化体系的 Bis-GMA 作防龋涂料,1973年用光敏固化充填材料修复折断牙的切缘。1979年2月开始,我们对48例楔状缺损患者的185枚患牙及43例釉质发育不全症患者的     

树脂单体对人牙龈成纤维细胞增殖活性和乳酸脱氢酶活性影响的体外研究

树脂修复体在口腔内由于受机械作用和化学侵蚀,其残余单体以及其他成分如引发剂或促进剂等缓慢释放,引起机体的不良反应。本研究通过测定人牙龈成纤维细胞的增殖活性(M TT分析)和乳酸脱氢酶(LD H)的活性来分析复合树脂单体的细胞毒性浓度。材料和方法人牙龈成纤维细胞的体外原代培养,传至7～8代用于实验。5种树脂单体用于实验,包括:甲基丙烯酸–2–羟乙酯(H EM A),甲基丙烯酸羟基炳基酯(H PM A),甲基丙烯酸二甲氨基乙酯(D M A E M A),双甲基丙烯酸二缩三乙二醇酯(TEG D M A)及双酚A双甲基丙烯酸缩水甘油酯(Bis-G M A)。分别用…     

新型低聚合收缩树脂材料的细胞毒性评价研究

目的评价一种新型低聚合收缩树脂基质材料对L929小鼠成纤维细胞的细胞毒性。方法将本课题组设计合成的具有低聚合收缩性能的树脂基质间三氟甲基苯基型丙烯酸酯3F-PAc与传统临床常用树脂基质Bis-GMA作比较,分为3组,分别为Bis-GMA组、3F-PAc 1组和3F-PAc 0组,3F-PAc 0组不添加稀释剂TEGDMA。制备3组材料浸提液,倍比稀释为4种浓度100%、50%、25%、12.5%;采用甲基噻唑基四唑(methyl thiazolyl tetrazolium,MTT)比色法检测小鼠成纤维细胞L929与各稀释液共培养1、3、5 d后的细胞相对增殖率并与阴性对照组作比较,评价细胞毒性等级。结果除培养3 d和5 d时BisGMA和3F-PAc 1组的100%浸液毒性等级为2级外,其余各实验组浸提液细胞毒性均为0~1级。3F-PAc 0组浸提液吸光度值大于3F-PAc 1组与Bis-GMA组,其差异具有统计学意义(P<0.05),3F-PAc 1组与Bis-GMA组之间差异不显著(P>0.05)。结论新型3F-PAc树脂基质材料无细胞毒性,具有较好的生物安全性;稀释剂TEGDMA可能是影响树脂材料细胞毒性的部分原因。     

螺环原酸酯对牙科基体树脂的改性研究

目的：用螺环原酸酯膨胀单体对牙科BisS-GMA基体树脂进行改性的研究。方法：分别以BisS-GMA和Bis-GMA作树脂基质,TEGDMA为稀释单体,加入和不加入螺环原酸酯膨胀单体,配制四种基体树脂。以CQ/DMAEMA为光引发体系,光固化后测定并比较其体积收缩率、聚合转化率、粘接拉伸强度和固化时间。结果：含膨胀单体的BisS-GMA基体树脂的体积收缩率较低,聚合转化率和粘接拉伸强度较高,且固化时间合适。结论：螺环原酸酯膨胀单体的开环聚合反应能使BisS-GMA基体树脂的体积收缩率显著降低,并能提高其聚合转化率和粘接拉伸强度。     

表面接枝技术对纤维加强树脂基桩力学性能的影响

目的探讨石英纤维表面接枝技术对纤维增强光固化树脂复合材料(FRC)桩力学性能的影响。方法将石英纤维随机分成5组分别进行以下表面处理:A组,10%H_2O_2浸泡20 min;B组,10%H_2O_2浸泡20 min+γ-MPS处理;C组,10%H_2O_2浸泡20 min+γ-MPS处理+Bis-GMA接枝1 h;D组,10%H_2O_2浸泡20 min+γ-MPS处理+Bis-GMA接枝3 h;E组,10%H_2O_2浸泡20min+γ-MPS处理+Bis-GMA接枝7 h。将处理好的石英纤维按相同体积比浸入光固化树脂基质中制成纤维增强树脂桩。测试试样的弯曲模量、弯曲强度、弯曲载荷,SEM观察断面的显微结构。结果不同接枝时间的石英纤维对FRC桩的力学性能有影响,其中E组力学性能明显提高,弯曲模量(24.65±2.20)GPa,弯曲强度(696.24±12.85)MPa,弯曲载荷(185.67±3.43)N,与其余组有显著差异(P<0.05)。结论纤维表面接枝技术能提高树脂基纤维桩材料的力学性能。     

牙科复合树脂及其浸出成分的细胞毒性

目的：观察4种含有不同成分的牙科复合树脂的细胞毒性,通过高效液相色谱法分析其浸出的成分。材料和方法：将复合树脂（Z100,Solitaire 2,Filtek P60．Synergy）制备成圆盘状测试试样,采用Balb／C 3T3成纤维细胞进行细胞毒性实验。在37℃条件下．实验第一部分为细胞与树脂接触72h（直接法）,第二部分则是细胞与树脂的乙醇浸泡提取液接触24h（间接法）。用MTT法{[3（4,5二甲基噻唑2）2,5二苯基]四氮唑嗅盐法}检测细胞存活率。结果：牙科复合树脂及其乙醇浸泡提取液对Balb／C 3T3成纤维细胞有毒性作用。单因素方差分析显示直接接触和间接接触各组间的差异均有统计学意义（P〈0.001）。组间比较（Tukey检验．α=0.05）显示直接法检测Synergy的毒性显著低于其他树脂．Solitaire 2毒性显著高于其他树脂。但是．间接法检测则为Synergy的浸泡提取液毒性显著高于其他树脂的提取液。采用高效液相色谱法检测各树脂中Bis—GMA,TEGDMA．UDMA．bis-EMA以及双酚A的含量,结果显示上述成分存在与否和其浓度各不相同。结论：牙科树脂的细胞毒性水平与其化学成分、浸泡介质以及浸出的成分和量相关。     

齿科复合树脂基质的研究进展

复合树脂通常由三个重要成份组成:1.树脂基质:①单体系统,②初始聚合反应的引发剂系统,③稳定剂系统.2.无机填料(如石英、玻璃粉、硅酸铝锂、瓷粉等).3.偶联剂(如有机硅).本综述回顾了齿科复合树脂基质(单体系统)的发展历程,主要为Bis-GMA(双酚A甲基丙烯酸缩水甘油酯)或其衍生化合物以及其他一些高分子化合物在复合树脂中的应用和研究.     

Volumetric dimensional changes of dental light-cured dimethacrylate resins after sorption of water or ethanol.

OBJECTIVES: This study evaluated the influence of water and ethanol sorption on the volumetric dimensional changes of resins prepared by light curing of Bis-GMA, Bis-EMA, UDMA, TEGDMA or D(3)MA. METHODS: The resin specimens (15mm diameterx1mm height) were immersed in water or ethanol 37+/-1 degrees C for 30 days. Volumetric changes of specimens were obtained via accurate mass measurements using Archimedes principle. The specimens were reconditioned by dry storage in an oven at 37+/-1 degrees C until constant mass was obtained and then immersed in water or ethanol for 30 days. The volumetric changes of specimens were determined and compared to those obtained from the first sorption. RESULTS: Resins showed similar volume increase during the first and second sorptions of water or ethanol. The volume increase due to water absorption is in the following order: poly-TEGDMA>poly-Bis-GMA>poly-UDMA>poly-Bis-EMA>poly-D(3)MA. On the contrary, the order in ethanol is poly-Bis-GMA>poly-UDMA>poly-TEGDMA>poly-Bis-EMA approximately poly-D(3)MA. The volume increase was found to depend linearly on the amount of water or ethanol absorbed. SIGNIFICANCE: In the choice of monomers for preparation of composite resin matrix the volume increase in the resin after immersion in water or ethanol must be taken into account. Resins of Bis-EMA and D(3)MA showed the lowest values.     

Catechin-incorporated dental copolymers inhibit growth of Streptococcus mutans

Objective:

To test the inhibitory growth activity of green tea catechin incorporated into dental resins compared to resins containing the broad-spectrum antimicrobial compound chlorhexidine against Streptococcus mutans in vitro.

Material and Methods:

The minimum inhibitory concentrations (MICs) of epigallocatechin-gallate (EGCg) and chlorhexidine (CHX) were determined according to the microdilution method. Resin discs (5 mm x 3 mm) were prepared from Bis-GMA/TEGDMA (R1) and Bis-GMA/CH₃Bis-GMA (R2) comonomers (n=9) containing: a) no drug, b) EGCg, c) CHX. Two concentrations of each drug (0.5x MIC and 1x MIC) were incorporated into the resin discs. Samples were individually immersed in a bacterial culture and incubated for 24 h at 37º C under constant agitation. Cell viability was assessed by counting the number of colonies on replica agar plates. Statistical analysis was performed using one-way ANOVA, Tukey and Student t-tests (α=0.05).

Results:

Both resins containing EGCg and CHX showed a significant inhibition of bacterial growth at both concentrations tested (p<0.05). A significantly higher inhibition was observed in response to resins containing CHX at 0.5x MIC and 1x MIC, and EGCg at 1x MIC when compared to EGCg at 0.5x MIC. Also, EGCg at 0.5x MIC in R1 had a significantly higher growth inhibition than in R2.

Conclusions:

Both EGCg and CHX retained their antibacterial activity when incorporated into the resin matrix. EGCg at 1x MIC in R1 and R2 resins significantly reduced S. mutans survival at a level similar to CHX. The data generated from this study will provide advances in the field of bioactive dental materials with the potential of improving the lifespan of resin-based restorations.     

Residual monomers (TEGDMA and Bis-GMA) of a set visible-light-cured dental composite resin when immersed in water

Rods of a visible-light-cured dental composite resin were photo-polymerized and immersed in water at 37 degrees C for 7 days. The residual monomers (TEGDMA and Bis-GMA) trapped in the set composite and those eluted into water were analysed by gas-liquid chromatography. It became evident that minor amounts of the residual monomers dissolved in water, but that most residual monomers remained in the set composite. Extension of the irradiation period contributed to the significant reduction in the residual monomer level and its elution into water.     

T-ZnOw树脂基托在不同pH值浸泡液中物理性能的变化

目的研究T-ZnOw树脂基托在不同pH值浸泡液中的物理性能。方法按质量比将5%的T-ZnOw添加到树脂基托中,37℃条件下,分别放入pH值=7的去离子水、pH值=6的人工唾液及pH值=5的醋酸溶液中浸泡,每24h更换浸泡液。分别在浸泡前、浸泡2周、4周、8周后取出试件,进行冲击强度、弯曲强度、硬度的检测。结果添加和未添加T-ZnOw的基托,浸泡2周后在不同浸泡液中,人工唾液组、醋酸溶液组和去离子水组的冲击强度与硬度无显著差异（P〉0.05）;人工唾液组的弯曲强度和弹性模量大于醋酸组,小于去离子水组,而醋酸组的弯曲强度与弹性模量小于去离子水组。浸泡4周、8周后,人工唾液组和醋酸溶液组的冲击强度、弯曲强度和弯曲弹性模量、硬度有不同程度降低,去离子水组物理性能无明显变化（P〉0.05）。在同一种浸泡液中,浸泡相同时间,添加T-ZnOw的基托的物理性能优于未添加者。结论 3种浸泡液中,去离子水浸泡对T-ZnOw树脂基托材料物理性能无明显影响。添加T-ZnOw的基托的物理性能优于未添加者。     

Novel light-cured resins and composites with improved physicochemical properties.

OBJECTIVES: The aim of this study was to determine the effect of two new diluent agents (Bis-GMA analogues), at different dilution levels and filler contents on relevant physicochemical properties of several novel resins and composites containing Bis-GMA as matrix. Composites using TEGDMA as diluent were used as control. METHODS: Twenty formulations were prepared combining three monomer mixtures (Bis-GMA/TEGDMA, Bis-GMA/CH(3) Bis-GMA and Bis-GMA/CF(3) Bis-GMA), at three dilution levels (85/15, 10/90, 0/100) and two percentages of filler loading (silanated barium aluminosilicate glass): 0%, 10%, 35%. Preliminary rheological testing was performed in order to obtain the viscosity of the resin samples. Resins and composites were then inserted into molds and light-cured (500mW/cm(2)). The properties evaluated were: (1) homogeneity of curing (HC), using FTIR or Vickers microindentor, (2) microhardness, by a Vickers microindentor, (3) depths of cure and oxygen inhibitor effect (OIE), quantified by scraping, (4) water contact angle on the materials surface, (5) water sorption and solubility, performed by the Oysaed-Ruyter method and (6) scanning electron microscopy analysis of the specimens surfaces. Data were analyzed by ANOVA and Student-Newman-Keuls tests (p<0.05). RESULTS: Materials with CH(3) Bis-GMA and CF(3) Bis-GMA exhibited less hydrophilicity, water sorption and solubility. Bis-GMA dilution induced an increase in depth of cure and promoted a higher OIE, particularly when the diluent was TEGDMA. Filler loading reduced the OIE and increased hydrophobicity of the resins. SIGNIFICANCE: CH(3) Bis-GMA may be considered as good candidate to be used as diluent because when replacing TEGDMA-induced lower hydrolytic degradation and increase in HC.     

Water sorption of CH3- and CF3-Bis-GMA based resins with additives

Objectives

To evaluate the effect of additives on the water sorption characteristics of Bis-GMA based copolymers and composites containing TEGDMA, CH₃Bis-GMA or CF₃Bis-GMA.

Material and methods

Fifteen experimental copolymers and corresponding composites were prepared combining Bis-GMA and TEGDMA, CH₃Bis-GMA or CF₃Bis-GMA, with aldehyde or diketone (24 and 32 mol%) totaling 30 groups. For composites, barium aluminosilicate glass and pyrogenic silica was added to comonomer mixtures. Photopolymerization was effected by 0.2 wt% each of camphorquinone and N,N-dimethyl-p-toluidine. Specimen densities in dry and water saturated conditions were obtained by Archimedes'' method. Water sorption and desorption were evaluated in a desorption-sorption-desorption cycle. Water uptake (%WU), water desorption (%WD), equilibrium solubility (ES; µg/mm³), swelling (f) and volume increase (%V) were calculated using appropriate equations.

Results

All resins with additives had increased %WU and ES. TEGDMA-containing systems presented higher %WU, %WD, ES, f and %V values, followed by resins based on CH₃Bis-GMA and CF₃Bis-GMA.

Conclusions

Aldehyde and diketone led to increases in the water sorption characteristics of experimental resins.     

Regulation of NaF release from bis-GMA/TEGDMA resin using gamma-methacryloxypropyltrimethoxysilane.

OBJECTIVES: The aim of this study was to evaluate the feasibility of regulation of NaF release from bis-GMA/TEGDMA resin using gamma-methacryloxypropyltrimethoxysilane (gamma-MPTS). METHODS: NaF powder was treated with gamma-MPTS to form a polysiloxane layer on its surface. The morphology and the composition of the NaF powder treated with gamma-MPTS were evaluated using scanning electron microscopy, infrared spectroscopy, contact angle measurement and X-ray photoelectron spectroscopy. Bis-GMA/TEGDMA resin containing 50 wt% NaF powder was prepared as a model resin and immersed in distilled water at 37 degrees C, and the amount of fluoride released from the resin was measured using a fluoride electrode. The mechanical strength in terms of diametral tensile strength before and after fluoride release was also measured, and statistically analyzed using one-way factorial ANOVA and Fisher's PLSD method. RESULTS: NaF powder was covered with hydrophobic gamma-MPTS delivered polysiloxane. A larger amount of fluoride was released at the initial stage from the resin containing NaF treated with no gamma-MPTS. However, fluoride release terminated in a relatively shorter period. In contrast, we observed a smaller amount of fluoride released for a longer period from the resin containing NaF treated with gamma-MPTS. SIGNIFICANCE: We found that gamma-MPTS treatment is useful for the regulation of NaF release from bis-GMA/TEGDMA resin. The mechanism of slow NaF release may be the formation of a hydrophobic polysiloxane layer on the surface of NaF powder and resulting slow water diffusion to NaF powder.     

Evaluation of two Bis-GMA analogues as potential monomer diluents to improve the mechanical properties of light-cured composite resins.

OBJECTIVES: The aim of this study was to investigate the influence of new diluent agents, diluent ratio and filler content, on relevant mechanical properties of several novel composite resins containing Bis-GMA as resin matrices, and to compare these with the properties of composites based on TEGDMA, a conventionally used diluent. METHODS: Two Bis-GMA analogues were synthesized and 20 experimental composite resins were prepared combining three monomer mixtures (Bis-GMA/TEGDMA, Bis-GMA/CH3 Bis-GMA and Bis-GMA/CF3 Bis-GMA), at three dilution rates (85/15, 10/90, 0/100) and three levels of hybrid filler content (barium aluminosilicate glass): 0, 10 and 35%. Flexural strength (FS), modulus of elasticity (ME) and microhardness (VHN) of the composites were evaluated. Five specimens of each material were prepared for each mechanical test, light-cured over 120 s and stored in water at 37 degrees C for 1 week. Three-point bending test was used for FS measurement and VHN was quantified by using a Vickers microindentor. Data were analyzed by ANOVA and Student-Newman-Keuls tests (P<0.05). RESULTS: Materials with CH3 Bis-GMA showed an enhanced VHN. Mean FS was higher for matrices containing TEGDMA. Overall, dilution favored FS and VHN but not ME. Filler loading specially improved ME and VHN. SIGNIFICANCE: Results correlate with an increase in the extent of polymerization due to the higher flexibility of the less viscous comonomer starting system and the hydrophobic character of the Bis-GMA analogues.     

Properties of fluoride-releasing light-activated resin cement.

OBJECTIVES: Fluoroaluminosilicate glass and poly(acrylic acid) in small water phase was incorporated into resin composite cements to reduce or prevent secondary caries around luted restorations. The purpose of this study was to investigate the physical properties and the amounts of fluoride released from four types of visible light-activated resin cements. METHODS: A powder was composed of silanized SiO2 filler and 4.5 wt.% (G-4.5), 9.5 wt.% (G-9.5) or 19.5 wt.% (G-19.5) fluoroaluminosilicate glass and 0.5 wt.% reducing agent. The 45.25 wt.% triethylene glycol dimethacrylate (TEGDMA), 45.25 wt.% 2-hydroxyethyl methacrylate (HEMA), 9 wt.% poly(acrylic acid) solution in water and 0.5 wt.% camphorquinone were contained in a liquid. The powder and liquid were mixed at a 3:1 ratio by weight and the three types of specimen disks were cured using a photo-curing lamp. The TEGDMA-based composite cement was used as control (G-0). The specimens were immersed in water at 37 degrees C for 24 h or 6 months and compressive strength (CS) and diametral tensile strength (DTS) were evaluated for the four experimental materials. Disks prepared from the four resin cements were also immersed in deionized distilled water at 37 degrees C, and the fluoride released was measured over a period of 24 weeks. RESULTS: G-9.5 specimens showed almost the same CS and DTS as G-4.5 and G-0 specimens and significantly higher values for both parameters than G-19.5 specimens after 6 months of water storage. The amount of fluoride released from the three fluoride-containing resin cements continued to increase over the entire experimental period. The fluoride release rates of G-9.5 and G-19.5 resin cements were almost the same and were significantly greater than that of the G-4.5 resin cement. SIGNIFICANCE: G-9.5 containing 9.5 wt.% fluoroaluminosilicate glass may be a clinically useful resin cement due to its favorable physical properties and fluoride release.     

Evaluation of methylene lactone monomers in dental resins.

alpha-Methylene-gamma-butyrolactone (MBL), which can be described as the cyclic analog of methyl methacrylate, exhibits greater reactivity in free radical polymerizations than conventional methacrylate monomers. Unfilled resin formulations composed of Bis-GMA/MBL or Bis-GMA/TEGDMA/MBL were light-cured. The effect of the more reactive methylene lactone monomer on mechanical properties and the degree of conversion of the polymers was examined. The infrared absorption bands for the carbon-carbon double bonds of MBL and the methacrylate monomers are well resolved and allow the conversion of each component to be calculated individually. The incorporation of a small amount of MBL (5 w/o) to Bis-GMA significantly increased the conversion; however, additional MBL (10 to 30 w/o) did not further increase the Bis-GMA conversion level. This appears to indicate an incompatibility between MBL and the bulky Bis-GMA monomer. Addition of 10 w/o MBL to Bis-GMA/TEGDMA (7:3) resulted in a cured resin with 71% methacrylate and 75% overall conversion efficiencies compared with the 57% conversion of the control formulation. The diametral tensile and the transverse strengths were approximately 10% greater for the MBL resin compared with the Bis-GMA/TEGDMA control; however, these differences were not statistically significant. The synthesis and polymerization of several substituted methylene lactones was also studied.