Post-curing of dental restorative resin

The post-curing of a bisphenol A-glycidyl-methacrylate based copolymer system at 37°C and 100 percent relative humidity was monitored using Fourier Transform IR (FT-IR). The dependence of degree of post-curing on the monomer and initiator components was investigated. The further polymerization achieved by elevating the temperature was measured using differential scanning calorimetry (DSC). The results clearly demonstrated that this free radical curing process was severely quenched by vitrification. Furthermore, a rapid loss in the reactivity to further curing was observed for the material in the quenched state, and this loss in reactivity was attributed to the decay of free radicals.     

Biological evaluation of a new organically modified ceramic-based dental restorative resin

Material tissue interactions of a newly developed organically modified ceramic (ormocer)-based dental restorative composite based on a resin containing mixture of alkoxides of silicone and calcium with polymerizable methacrylate end groups are discussed in this study. Admira, a commercially available ormocer was used as control. A sol–gel process has been used to synthesize organically modified ceramic resins from liquid precursors, which allow one to produce inorganic–organic hybrid polymer materials, which can be functionalized to optimize their physical and chemical properties. Besides, the resulting material properties have been significantly modified by further technological processing such as photochemical curing of the materials by incorporating dimethacrylate groups as organically polymerizable units. Intracutaneous (intradermal) irritation test is found not to elicit any gross signs of tissue reaction. The results of maximization test for delayed hypersensitivity also did not show any adverse skin reaction during the induction or challenge period. Histological analysis after 1, 4, and 12 weeks of subcutaneous implantation of restorative composite resin on the dorsal surface on one side of the spinal column of Wister rats is also found not to reveal any inflammatory response after the implantation. Granuloma and material debris is found to be absent in all three periods of implantation in both test and control. No necrosis was observed around the implanted materials, which were found to be encapsulated by fibrous connective tissue consisting of predominantly fibroblasts and inflammatory cells. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Development and status of resin composite as dental restorative materials

Dental composites are comprised of a polymerizable matrix and reinforcing fillers that can be hardened into a solid restoration in the prepared tooth cavity. Composites are becoming increasingly popular due to their esthetics and improved mechanical and physical properties. However, dental composites still encounter several problems, mainly secondary (recurrent) caries, restoration fracture, excessive wear, marginal degradation, and tooth sensitivity. Therefore, extensive efforts are underway to improve the composite compositions and microstructure, and enhance their clinical performance and longevity. Relying on advances in materials science and technology, dental composites have been continuously improved and their clinical applications have been expanded. In this review article, the development of dental composites was summarized, including compositional changes, performance improvements in key areas, current research hot spots, and outlook for future direction. The intention is to provide a review of the history and development of dental composites with a discussion of strategies on addressing the current challenges facing dental composites. In addition, this review will provide a better understanding of dental composites and their properties for the practicing clinicians, to contribute to improving the quality of composite restorations. The review of literature indicates that while current composites are generally bio-inert and can replace the missing tooth structure, future composites should be bioactive and therapeutic to inhibit caries, modulate biofilms, and protect the surrounding tooth structures, in order to increase the restoration longevity. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48180.     

Compatibility of silorane composite repaired with methacrylate-based restorative systems

The aim of this study was to evaluate the repair bond strength of silorane composites using either the silorane or methacrylate-based restorative systems. Expired silorane composite was used as the substrate material in all experimental groups. Silorane blocks (5?×?5?×?4?mm) were fabricated and stored at 37?°C for 24?h. Six experimental groups were developed according to the repair: I-silorane composite (no intermediary); II-P90 Bond/Silorane; III-P90 Adhesive System (primer/bond)/silorane; IV-P90 bond/Scotchbond Universal/methacrylate composite (Filtek P60); V-Scotchbond Universal/methacrylate; and VI-silane/Adper Single Bond 2/methacrylate. The repaired blocks were stored for 24?h at 37?°C, and then sectioned, yielding stick-shaped specimens (0.5?mm²) that were tested in tensile (0.5?mm/min). The results were analyzed using ANOVA/Tukey test (α?=?0.05). The interfacial micromorphology and nanoleakage were also analyzed under SEM. Scotchbond Universal/methacrylate composite, either associated with the P90 bond or not, exhibited similar bond strength to that of P90 Adhesive System/silorane composite. Scotchbond Universal either associated with the P90 Bond or not to repair the silorane allowed no pre-testing failures. The worst scenarios were repairing the silorane with no intermediary (G-I) or combination silane/Adper Single Bond 2/methacrylate composite (G-VI) that presented significantly lower bond strengths and higher incidences of pre-failure testing. The importance of the silane was not confirmed. Characteristic micromorphology and no signs of nanoleakage were identified in all experimental groups. The silane-containing, phosphorylated methacrylate-based adhesive associated with a methacrylate composite was proven to reliably repair the expired composite in a similar way to that of the application of dedicated silorane adhesive.     

超支化聚酯的改性及其在牙科修复树脂中的应用

以季戊四醇(B4单体)为核,2,2-二羟甲基丙酸(AB2单体)为单体,对甲苯磺酸为催化剂,通过熔融缩聚反应合成末端为16个羟基的二代Boltorn型超支化聚酯HBP。并进一步用甲基丙烯酰氯、丙酰氯对端羟基进行改性,在HBP末端全部引入双键或部分引入双键,得改性后超支化聚酯GHBP1和GHBP2。在传统牙科修复树脂双酚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)的混合体系中引入不同质量分数的GHBP,考察其对树脂收缩率和双键转化率的影响。结果表明,GHBP改性牙科修复树脂后,树脂的聚合收缩明显降低,且GHBP2具有更优异的减小收缩的性能,但双键转化率无明显变化。     

Synthesis,characterization, and curing of a new acrylate‐based dental restorative resin

The synthesis of monomer 1,3‐bis [(2‐hydroxy‐3‐acrylate) propyloxy]2‐hydroxy propane (BHAPP) is reported for the possible use in dental restoratives. The monomer was prepared by the reaction of acrylic acid with diglycerol diglycidyl ether (DGE) in the presence of triethyl amine as a catalyst. The progress of the reaction at 60°C followed by measuring the intensity of the epoxide absorption peak at 915 cm^?1 which has reached to its minimum value after 5 h. The structure of the monomer was characterized by FTIR and ¹H‐NMR. The monomer was a moderately viscous light yellow color liquid having a refractive index of 1.544. Thermal curing of the monomer in DSC in the presence of benzoyl peroxide showed exothermic peak with maximum temperature (T_p) varied from 89 to 107°C depending on the heating rate and activation energy of 83 kJ/mol. Photopolymerization of the monomer by visible light in the presence of camphorquinone and N,N‐dimethylaminoethyl methacrylate as the photoinitiating system showed maximum 60% conversion after 40 s exposure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Studies on the preparation and dental properties of antibacterial polymeric dental restorative composites containing alkylated ammonium chloride derivatives

The preparation of antibacterial polymeric dental restorative composites (PDRC) was carried out using various alkylated ammonium chloride derivatives as the antibacterial compound. To improve the mechanical properties of PDRC, the surface of the silica filler was hydrophobically treated with γ-methacryloxypropyltrimethoxysilane. The diametral tensile strength, flexural strength, and Knoop hardness of PDRC were measured and the antibacterial effect was also investigated. The addition of alkylated ammonium chloride derivatives to the bisphenol-A glycerolate dimethacrylate/triethyleneglycol dimethacrylate resin matrix enhanced the antibacterial properties of PDRC. It was also discovered that alkylated ammonium chloride derivatives with a higher chain length between the ammonium and the acryl (or methacryl) functional groups reduced the mechanical properties of PDRC. In addition, it was found that the optimum concentration of the antibacterial compound was about 3 wt% based upon resin matrix, and the optimum chain length between functional groups of alkylated ammonium chloride derivatives was 2–3 carbons.     

二元共聚高吸油树脂的合成工艺

以甲基丙烯酸丁酯及苯乙烯为主要单体、丙二醇二丙烯酸酯为交联剂、偶氮二异丁腈为引发剂,采用悬浮聚合方法,合成一种白色颗粒状的共聚型高吸油树脂。考察了搅拌速率、分散剂浓度、聚合温度、单体配比、交联剂用量等因素对颗粒特性的影响。研究结果表明,当共聚单体配比(质量比)为1.6∶1、分散剂水溶液浓度为0.1%～0.2%、交联剂用量为单体质量的1%、搅拌转速200～300 r/min、聚合温度70℃、聚合时间为6h时,合成出的树脂粒径适中,吸油倍率达到20倍。     

Physical characterization of a self‐healing dental restorative material

The objectives of this study were to determine the efficacy of self‐healing a highly filled composite and to investigate the physical properties of a model dental compound formulated to autonomically heal cracks. A visible light cured model resin consisting of TEGMA : UDMA : BisGMA (1 : 1 : 1) at 45% w/w with silane 0.7 μ glass was formulated with a self‐healing system consisting of encapsulated dicyclopentadiene and Grubbs' catalyst. The base resin was also formulated and characterized with the microcapsules alone, Grubbs' catalyst alone, and no healing additives. Fracture toughness (K_Ic) was assessed using single edge notch specimens in three‐point bend (n = 12). Data was analyzed with ANOVA/Tukey's at p ≤ 0.05. DMA was performed from ?140 to 250°C at 2°/min and 1 Hz. Storage and loss modulus, T_g and tan δ, was recorded for each material. The self‐healing material was loaded to failure, was left to sit for 7 days and then loaded a second time to failure to determine healing in the material. These specimens had a K_Ic = 0.69 ± 0.072 for a 57% average recovery rate of the original fracture toughness. The fracture toughness of the self‐healing material was statistically similar to the control. The modulus decreased in the composites with encapsulated dicyclopentadiene. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

苯基胍胺甲醛树脂合成研究

苯基胍胺甲醛（ＢＧＦ）树脂聚合度为２～４时,其性能最好,并可降低固化温度。探讨了采用共溶剂水醇体系在缩聚反应中ｐＨ值、水／醇体积比、加水时间等对ＢＧＦ树脂分子量分布的影响,最终制得单体含量为１７％,２～４聚体含量为６６％,固含量约３０％的ＢＧＦ树脂。     

新型含磷环氧树脂的合成及性能研究

合成了一种新型含磷环氧树脂,采用化学分析和红外光谱研究了其结构及反应特性。采用DSC、UL-94垂直燃烧试验和氧指数法表征了含磷环氧树脂/4,4′-二氨基二苯砜(DDS)固化体系的玻璃化温度和阻燃性能,并测定了其拉剪性能及吸水率等。结果表明,含磷环氧树脂的最佳合成反应条件为:反应温度150℃,反应时间150 min,最佳固化工艺为130℃/1 h+160℃/2 h+180℃/2 h+200℃/2 h。磷质量分数为2%时,阻燃效果可达到UL-94-V-0级,同时具有较高的力学强度;固化物玻璃化温度为126℃,吸水率0.24%。该树脂可用于覆铜板等电子产品制造中,可操作性强,成本低。     

强酸性阳离子交换树脂催化合成甲酸辛酯的研究

以甲酸、正辛醇为原料,直接酯化合成甲酸辛酯,研究了反应温度、反应时间、原料配比、带水剂、催化剂用量等对反应的影响。结果表明,合成甲酸辛酯的最佳工艺条件是:反应温度100℃,反应时间30min,甲酸与正辛醇物质的摩尔比为1.2∶1,催化剂用量为0.5g,带水剂环己烷为12.5mL(正辛醇为0.15mol的情况下)。甲酸辛酯的收率达到95.94%。该催化剂具有价廉易得、催化活性好、不腐蚀设备、无环境污染等优点,不经处理可循环使用多次。     

微悬浮法PVC糊树脂的合成研究

采用三氯乙烯作为氯乙烯模拟液,研究主/助乳化剂结构、用量和比例等对分散液滴粒径及粒度分布的影响。采用5 L高压夹套釜进行氯乙烯微悬浮聚合,研究主/助乳化剂结构、用量、比例和水油比对PVC初级粒子平均粒径和粒度分布的影响。发现以十二烷基硫酸钠(SDS)为主乳化剂时分散液滴的尺寸最小,PVC胶乳稳定,粒度分布窄;随着脂肪醇助乳化剂链长的增加,分散液滴尺寸明显减小,十六醇、十八醇或两者的混合醇是氯乙烯微悬浮聚合适宜的助乳化剂;随着十六醇或十六~十八混合醇与SDS用量比的增加,分散液滴和PVC胶乳粒子的尺寸逐渐减小,粒度分布趋窄。微悬浮聚合PVC糊树脂包含粒径范围较宽但呈连续分布的初级粒子,通过主/助乳化剂用量比的改变,可调节PVC初级粒子的平均粒径及粒度分布。     

Studies on shrinkage,depth of cure,and cytotoxic behavior of novel organically modified ceramic based dental restorative resins

Polymerization shrinkage, depth of cure, and in vitro cytotoxic behavior of dental restorative composite based on inorganic–organic hybrid (organically modified ceramic) resins, containing alkoxides of silicone, calcium, and titanium with various polymeric methacrylate groups were evaluated in this study. Comparison was made between dimethacrylate and tetra methacrylate resins. Statistical evaluation using analysis of variance (single factor) showed that tetramethacrylate organically modified ceramic resin‐based composites showed better shrinkage properties. P < 0.05 was considered as statistically significant. Compared to dimethacrylates, tetramethacrylates based composites showed lower depth of cure value. Cytotoxicity characteristics of these composites were mainly depending on the nature of inorganic material incorporated rather than difference in dimethacrylate or tetramethacrylate structure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

环硫丙烯酸酯树脂的合成反应研究

将双酚A型环硫树脂ES128,ES128/环氧树脂CYD128混合物分别与丙烯酸反应制备了环硫丙烯酸树脂及环硫/环氧丙烯酸酯树脂。以红外光谱表征了产物结构,讨论了反应机理,并对丙烯酸用量,溶剂及加料顺序等对反应的影响进行了研究。结果表明:较佳的合成工艺条件为:甲苯为溶剂,环氧官能团与丙烯酸物质的量比为1∶2,反应温度90℃,反应时间4.5 h。工艺操作为先加入丙烯酸,再升温加入催化剂N,N-二甲基苄胺,可有效防止凝胶现象发生。与环氧官能团相比,环硫官能团与丙烯酸的反应活性较低。     

双环戊二烯石油树脂的合成研究

以双环戊二烯(DCPD)为原料,采用热聚合方法得到粗DCPD石油树脂,然后采用固定床反应装置对粗DCPD石油树脂进行加氢研究,以得到热稳定性优良的加氢石油树脂。确定了热聚合最佳工艺条件:m(双环戊二烯)∶m(环己烷)=1∶1,反应温度为270～275℃,反应时间6～8h,粗品色度(Gardner)10#～12#,软化点为130℃;采用钯催化剂考察了加氢过程中各种工艺参数的影响,最佳工艺条件为∶w(DCPD石油树脂)=20%～25%,反应温度280～290℃,反应压力(5.0～6.0)MPa,空速0.5h-1,V(氢)∶V(油)=300∶1,得到的DCPD加氢石油树脂色度(Gardner)1#,软化点125℃。     

Synthesis and characterization of phosphorus-containing methacrylate-based difunctional crosslinkers and their use in UV-curable resin systems

Two new phosphorus-containing methacrylate-based difunctional crosslinking agents [bis(4-(2-methacryloyloxy)ethyl carboxyl)phenyl phosphine oxide (BEPPPO) and bis(4-(2-methacryloyloxy)ethylcarbonylaminophenyl)phenyl phosphine oxide (BUPPPO)], which can be good candidates for UV-curable coating applications, were synthesized by reacting either a phosphorus-containing diisocyanate [bis(4-isocyanatophenyl)phenyl phosphine oxide] or a phosphorus-containing diacid chloride [bis(4-chloroformylphenyl)phenyl phosphine oxide] with hydroxyethyl methacrylate. The structures of the monomers thus obtained were characterized by FTIR, mass, and ¹H-NMR spectroscopies. The contents of the new crosslinking agents in the UV-cured polymeric films were varied between 10 and 30% by weight. Mechanical, physical, and thermal characterizations of the UV-cured films were investigated. An increase in crosslinking agent content caused an increse in mechanical properties. Films containing BUPPPO had higher tensile strength values compared to the films containing BEPPPO. Thermogravimetric analysis of phosphorus-containing crosslinking agents revealed that incorporating phosphorus into the structure resulted in a high char yield up to 24.5% at 600°C. Water absorption values of UV-cured films were also affected by the amount and type of crosslinking agent. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2575–2585, 1999     

丙烯酸酯系共聚物高吸油树脂的合成及性能研究

以甲基丙烯酸十八酯（SMA）、丙烯酸丁酯（BA）和苯乙烯（St）为单体，二乙烯苯（DVB）为交联剂，过氧化苯甲酰（BPO）作引发剂，采用悬浮聚合法合成高吸油性树脂。以吸油率作为性能指标，利用正交试验分析各种反应因素对树脂吸油率的影响，得出最佳工艺条件，并系统研究了体系中单体组成及配比、交联剂、引发荆、分散剂及致孔剂用量等因素对吸油树脂性能的影响。结果表明，当m（SMA）：m（BA）：m（St）=42：58：8，ω（BPO）=1.0％，ω（DVB）=1．2％，ω（PVA）=0．2％，ω（CHCl3）=10％时，树脂吸油率达到最大，可吸收四氯化碳23．61g／g，甲苯22．58g／g，笨18．85g／g，柴油14.8g／g。树脂的保油率在90％以上。经过热重分析可知，树脂的稳定性比较好，分解温度在333．7℃。     

Structural,mechanical, and biocompatibility analyses of a novel dental restorative nanocomposite

Structure and biocompatibility are key parameters that determine the usefulness of dental materials for clinical use. Novel polyurethane (PU) nanocomposite material was prepared by chemically binding nanohydroxyapatite (nHA) to the diisocyanate component of the PU backbone by solvent‐polymerization. nHA was incorporated into PU by the stepwise addition of monomeric units of the PU. The PU/nHA composite was analyzed by ¹³C Nuclear magnetic resonance (structural) and X‐ray diffraction (phase analysis). The tensile strength and elastic modulus was evaluated for mechanical properties. These analyses revealed linkage between the hard‐ and soft‐segments are urethane linkage and showed high mechanical properties with increase in content of nHA. To assess biocompatibility osteoblast cells were seeded on to the material and allowed to adhere and proliferate. Osteoblast‐like cell growth and proliferation was assessed by MTS assay. It was found that cells adhered and proliferated on these novel substrates. To test bacterial adhesion discs of composite with and without nHA were incubated with standardized suspensions of oral bacterium Streptococcus sanguinis strain NCTC 7863. PU composites with nHA exhibited biocompatibility with respect to mammalian cell growth and showed significantly reduced bacterial adhesion as compared to PU alone. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

环氧接枝改性水性丙烯酸树脂的合成研究

通过丙烯酸酯类单体与环氧树脂接枝共聚反应,对水性丙烯酸树脂进行改性。研究了环氧树脂种类、用量、加料方式、反应温度及中和度等因素对其性能的影响。研究结果表明,当环氧树脂E-44在反应前期加入,用量为6%~9%(占总单体质量分数),反应温度为110℃,中和度为110%时,改性树脂具有较好的成膜性能和优异的物理机械性能。红外光谱分析证实接枝产物的存在;用扫描电镜观察了接枝共聚物的水分散体的粒子形态及大小。