卤素和LED光固化灯照射复合树脂的机械强度比较

目的探讨3M2500型卤素光固化灯和3M FreeLight型LED光固化灯对光固化复合树脂机械强度及固化深度的影响。方法用WD-5A型电子拉力试验机、DUH-W201S型动态超显微硬度计2种仪器,通过测试比较卤素光固化灯和LED光固化灯照射Tetric ceram HB(Vivadent)A2色光固化复合树脂后其挠曲强度、压缩强度、表面硬度、固化深度的差异,从而比较3M2500型卤素光固化灯和3M FreeLight型LED光固化灯的性能。结果卤素光固化灯照射Tetric ceram HB复合树脂40s,LED光固化灯照射Tetric ceram HB10s,前者固化深度平均可达3.98mm,后者固化深度平均可达2.136mm,两者均可完全固化2mm,LED光固化灯固化树脂深度低于卤素光固化灯;表面硬度DHT115平均值分别为73.292MPa和39.668MPa,统计学分析95%水平有差别(P<0.05),LED灯对应的树脂硬度低于卤素灯;压缩强度平均值分别为242.1MPa和287.7MPa,统计学分析95%水平无明显差别(P>0.05);挠曲强度平均值分别为88.9MPa和97.0MPa,统计学分析95%水平无明显差别(P>0.05)。结论LED灯照射Tetric ceram HB复合树脂10s能达到卤素灯照射Tetric ceram HB复合树脂40s的聚合水平,适合于口腔临床应用。     

可见光固化复合树脂在前牙美观与修复中的临床应用

成人前牙的美观与修复,随着粘结技术与可见光固化复合树脂等新技术的相继问世,展示了美好的前景。 我科采用广东省化学纤维研究所与我校南方医院联合研制成功的GD型可见光固化复合树脂充填材料,与可见光光源—GD型光固化灯(波长为400-560nm),     

可见光固化基托树脂研究

研究了可见光固化基托树脂的基质树脂、多功能单体和光引发体系的合成工艺以及粘度调整剂、基托树脂、处理剂、空气遮蔽剂的制备工艺;讨论了基质树脂结构、交联剂结构、光引发体系、光照时间以及不同光源照射等因素对光固化基托树脂物理性能的影响;还讨论了光固化基托树脂的色泽稳定性以及空气遮蔽剂、气泡对光固化基托树脂表面形态的影响。     

可见光复合树脂应用的点滴体会

可见光复合树脂是新型的光固化复合树脂,有其独特的一些优点。近年来发展很快,渐渐受到口腔医学界重视,已广泛应用于临床。一、可见光复合树脂及其固化器的特性可见光复合树脂是由多官能度的树脂及混合型或超微型的无机填料组成,此外,还有光敏剂、还原剂、阻聚剂、看色剂等。可见光固化器是由钨卤素灯、光导管、开关、定时器、散热装置等组成。有的安装有滤光片。波声长一般在450～550nm范围,有效波长470～510nm。光传导有液态或玻璃纤维的光导管、石英棒等。电压的变化对光强     

光照射后固化对于大块充填树脂性能的影响

光照射后固化因为有利于大块充填树脂各种性能的提高,日益引起关注.其中光照射后固化对于提高复合树脂双键转化率、增加硬度、减小聚合收缩应力均有较好的效果.温度、光固化反应的双键转化率、树脂组成成分和浸泡溶剂等因素都可以影响大块充填树脂的光照射后固化.本文将对以上内容及其对临床意义进行综述.     

Dentsply 470光固化机的原理及维修

光固化机是一种利用聚合光固化修复树脂材料的卤素光装置。随着光固化技术在口腔牙病的治疗和修复中日益广泛的应用,光固化设备的种类及型     

“兰色可见光防护镜”已批量生产

可见光树脂固化器产生的光波(400～500波长的兰色可见光),对人眼有一定程度损伤,国外部分生产可见光树脂固化器的厂家已有此类专用防护镜配套。中国科学院西安光机所与第四军医大学口腔医院共同研制的“兰色可见光防护镜”能够100％滤除低于520nm波长的可见光,同时可透过91％以上高于520nm波长的     

复合树脂贴面的透光率

复合树脂已广泛应用于口腔变色牙的美容治疗 ,临床治疗变色牙一般采用直接法贴面或间接法贴面。间接贴面法是将已成型固化的复合树脂贴面置于变色牙上 ,再用光固化树脂或自凝树脂将贴面粘结于牙面上 ,复合树脂贴面对光具有一定的折射和反射作用。本文应用日立 (Hitachl) -3 70分光色彩分析仪对几种常用复合树脂贴面的透光率进行了测试。1　材料和方法1.1　材料及处理方法见表 1。表 1　材料及处理方法树脂出厂色调填料固化方式Durafill古莎A10超微光固化Chairsma古莎A10混合光固化Artgalss古莎DA10混合光固化Isosit列支敦士登D 1B超微…     

口腔材料学教学实验课设计:光照条件对光固化复合树脂性能的影响

光固化复合树脂经光固化灯照射后固化,其临床性能在很大程度上受所用的光固化灯的影响,特别是光照强度和光照时间对其影响更为显着。为了帮助学生了解光照条件对光固化复合树脂性能的影响,北京大学口腔医学院在口腔材料学实验课教学中设计了两个实验:光固化复合树脂的固化深度实验和光固化复合树脂的挠曲强度实验。通过实验使学生掌握光照射时间和光照强度对光固化复合树脂固化深度和挠曲强度的影响规律。实验设计完成后,在2008级的八年制学生中进行了实际使用,并根据实验内容设计了调查问卷。问卷结果显示,实验课效果良好。     

二期热处理对光固化树脂物理性能的影响

随着光固化复合树脂在修复领域应用范围的不断扩大,进一步提高光固化树脂物理性能,越来越受到了广泛的关注。光固化复合树脂是由一定波长的光引发光敏剂分解,而引发整个树脂聚合的,其基质树脂常常聚合不完全,因而其物理性能没有达到完全固化树脂所应有的性能。为了提高光固化复合树脂的物理性能,常常     

The application of magnetic resonance microimaging to the visible light curing of dental resins. Part 2. Dynamic imaging by the FLASH-MOVIE pulse sequence.

OBJECTIVES: To investigate the application of a rapid NMR imaging pulse sequence, FLASH-MOVIE, to the visible light curing of dental restorative materials. METHODS: The light guide was applied at one end of a cylindrical specimen of visible light curing unfilled resin and the light directed along the cylinder. During polymerisation an NMR imaging pulse sequence, FLASH-MOVIE, was run at 15s intervals with a 50 ms repetition time. The image of a 1mm thick vertical slice was recorded with a (125 microm)2 pixel size. RESULTS: Images with good contrast were obtained from all resin monomers. The image intensity from the polymer was indistinguishable from the background intensity. Thus, the progress of light activated polymerisation in the material could be followed in real time through a series of up to 16 images. Initially the image intensity increased in the material closest to the light guide, then decreased over time to zero. Concomitant with this fall, a "cure-front" moved through the specimen. SIGNIFICANCE: The FLASH-MOVIE NMR pulse sequence applied to microimaging of dental diacrylate resins can be used to obtain a dynamic record of visible light curing. A more refined experimental protocol will be required to apply this unique data to models proposed for this polymerisation mechanism.     

Response of THP-1 monocytes to blue light from dental curing lights

Blue light curing units (wavelengths of 400-500 nm) are a mainstay of restorative dentistry, and several high-intensity light sources have been developed to polymerize resin composites more rapidly. The biological safety of visible light has been assumed, but some reports of adverse biological effects of blue light in non-dental contexts support further evaluation of the biological safety of high-intensity blue light. The current study tested the hypothesis that blue light provokes cell stress responses resulting in the secretion of cytokines or expression of heat-shock proteins (HSP) in monocytes. Human monocytic cells were irradiated with three light sources (quartz-tungsten-halogen, plasma-arc and laser), then cellular proliferation, secretion of the inflammatory cytokine TNFalpha and induction of HSP72 were measured. Results indicated that although all three light sources significantly inhibited proliferation of monocytes, the secretion of TNFalpha was not induced following exposure to blue light and was not potentiated with administration of the activator lipopolysaccharide. Similarly, treatment with the plasma-arc light, which caused the largest temperature increase in previous studies, did not induce HSP72. The current results do not support activation of monocytes by blue light as an inflammatory risk factor in dental tissues during curing of composites. However, the results of the current study should be further verified in primary monocytes and an animal model before decisions about clinical risks are made.     

Determination of double bond conversion in dental resins by near infrared spectroscopy.

OBJECTIVES: This study determined the validity and practicality of near infrared (NIR) spectroscopic techniques for measurement of conversion in dental resins. METHODS: Conversion measurements by NIR and mid-IR were compared using two techniques: (1) The conversion of 3mm thick photopolymerized Bis-GMA/TEGDMA resin specimens was determined by transmission NIR. Specimens were then ground and reanalyzed in KBr pellet form by mid-IR. (2) As further verification, thin resin films were photocured and analyzed by mid-IR. Multiple thin films were then compressed into a thick pellet for examination by NIR. RESULTS: Conversion values obtained by NIR and mid-IR techniques did not differ significantly. A correction for changing specimen thickness due to polymerization shrinkage was applied to NIR conversion measurements since an internal standard reference peak was not employed. Sensitivity of the NIR technique was superior to those based on the mid-IR. SIGNIFICANCE: The nondestructive analysis of conversion in dental resins by NIR offers advantages of convenience, practical specimen dimensions and precision compared with standard mid-IR analytical procedures. Because glass is virtually transparent in the NIR spectrum, this technique has excellent potential for use with filled dental resins as well.     

Thermographic investigation of contemporary resin-containing dental materials

OBJECTIVES: To measure the temperature rise induced during visible light curing of modern resin-containing dental materials and the effect of dentine sections in reducing this temperature rise. METHODS: A variety of newly introduced resin-containing materials were investigated, including flowable, packable and conventional hybrid composites, as well as a compomer and a resin modified glass ionomer material. The resin was packed into polytetrafluoroethylene (PTFE) moulds and cured for 40s. Temperature rises on the undersurface of the curing resin were measured using the Thermovision 900 infra-red scanning system. In the second part of the study, extracted, caries free teeth were sectioned into dentine disks of three thicknesses (0.7, 1.4 and 1.9 mm). Composite samples were overlaid by the disks and the insulating effect of dentine measured. RESULTS: The maximum temperature increases were: 43.1 degrees C (flowable composite), 32.8 degrees C (conventional composite), 32.8 degrees C (RMGI), 23.3 degrees C (compomer) and 22.4 degrees C (packable composite). CONCLUSIONS: There was a quantifiable amount of heat generated in resin-containing material during light curing. Dentine sections were good thermal insulators that significantly reduced temperature rises associated with resin composite photocuring.     

A comparison of monomer conversion and inorganic filler content in visible light-cured denture resins.

Visible light-cured (VLC) denture resins are relatively new products used for the reline and repair of dentures. The conversion of monomer into polymer in 3 brands of visible light-cured denture resins was investigated. The relationship of the inorganic filler content to this conversion was also studied. It was determined that these reline materials vary in monomer conversion and weight percentage of filler, and this variation is brand dependent. The monomer conversion ranged from 77% to 97%. Significant differences in these values were found when duration of light exposure was increased. In addition, resin nearest to the light source polymerized to a greater extent when compared to resin that was 1 mm deep to this surface, hence furthest from the light source. The inorganic filler content ranged from 0% to 15%. For the resin systems studied, the relationship between monomer conversion and inorganic filler loading was inversely proportional. Results indicated that monomer conversion of VLC repair resins was affected by the duration of light exposure as well as the amount of inorganic filler present in the material.     

Low shrinkage light curable nanocomposite for dental restorative material.

OBJECTIVES: The aim of this study was to develop a low shrinkage visible light curable nanocomposite dental restorative material without sacrificing the other properties of conventional materials. This nanocomposite was developed by using an epoxy resin 3,4-epoxycyclohexylmethyl-(3,4-epoxy)cyclohexane carboxylate (ERL4221) matrix with 55% wt of 70-100 nm nanosilica fillers through ring-opening polymerization. GPS (gamma-glycidoxypropyl trimethoxysilane) was used to modify the surfaces of silica nanoparticles. RESULTS: The nanocomposite was shown to exhibit low polymerization shrinkage strain, which is only a quarter of currently used methacrylate-based composites. It also exhibited a low thermal expansion coefficient of 49.8 microm/m degrees C which is comparable to that of the methacrylate based composites (51.2 microm/m degrees C). The strong interfacial interactions between the resin and fillers at nanoscales were demonstrated by an observed high strength and high thermal stability of the nanocomposite. A microhardness of 62 KHN and a tensile strength of 47 MPa were reached. A high degree of conversion ( approximately 70%) can be obtained after less than 60 s of irradiation upon the nanocomposite. A transmission electron microscope (TEM) study of the nanocomposite showed no aggregation of fillers. Comparable results to the methacrylate based composites were obtained from the one day MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) cytotoxicity test. SIGNIFICANCE: The developed epoxy resin based nanocomposite demonstrated low shrinkage and high strength and is suitable for dental restorative material applications.     

Clinical strategies for esthetic excellence in anterior tooth restorations: understanding color and composite resin selection

Direct composite resin restorations have become a viable alternative for patients that require anterior restorative procedures to be integrated to the other teeth that compose the smile, especially for presenting satisfactory esthetic results and minimum wear of the dental structure. Technological evolution along with a better understanding of the behavior of dental tissues to light incidence has allowed the development of new composite resins with better mechanical and optical properties, making possible a more artistic approach for anterior restorations. The combination of the increasing demand of patients for esthetics and the capacity to preserve the dental structure resulted in the development of different incremental techniques for restoring fractured anterior teeth in a natural way. In order to achieve esthetic excellence, dentists should understand and apply artistic and scientific principles when choosing color of restorative materials, as well as during the insertion of the composite resin. The discussion of these strategies will be divided into two papers. In this paper, the criteria for color and material selection to obtain a natural reproduction of the lost dental structures and an imperceptible restoration will be addressed.     

Light activated resin containing organic dyestuff

The physical properties of experimental visible light-activated resins containing dyestuff, which could be quickly discolored by irradiation was, evaluated by analyzing light absorbance characteristics and measuring micro Vickers hardness. The experimental resin, which was prepared by mixing equivalent weights of Bis GMA and triethyleneglycol-dimethacrylate, was colored by one of three organic dye stuffs, and camphorquinone and dimethyl-p-toluidine were added to activate polymerization. In the tested materials, the experimental resins containing Methylene blue and Nile blue A were discolored quickly after the start of irradiation, and this was considered to be useful for dental practice because an overfilled margin could be easily identified. The Vickers hardness number of the base resin decreased slightly by a level of 6% by adding the dyestuff.     

Shining a light on high volume photocurable materials

Spatial and temporal control is a key advantage for placement and rapid setting of light-activated resin composites. Conventionally, placement of multiple thin layers (<2 mm) reduces the effect of light attenuation through highly filled and pigmented materials to increase polymerisation at the base of the restoration. However, and although light curing greater than 2 mm thick layers is not an entirely new phenomenon, the desire amongst dental practitioners for even more rapid processing in deep cavities has led to the growing acceptance of so-called “bulk fill” (4–6 mm thick) resin composites that are irradiated for 10–20 s in daily clinical practice. The change in light transmission and attenuation during photopolymerisation are complex and related to path length, absorption properties of the photoinitiator and pigment, optical properties of the resin and filler and filler morphology. Understanding how light is transmitted through depth is therefore critical for ensuring optimal material properties at the base of thick increments. This article will briefly highlight the advent of current commercial materials that rationalise bulk filling techniques in dentistry, the relationship between light transmission and polymerisation and how optimal curing depths might be achieved.     

Repairs with visible light-curing denture base materials

Visible light-curing interpenetrating networks are newly developed materials suitable for several dental applications. These materials have several advantages, including versatility and good physicomechanical properties, but also present some weaknesses, such as increased water sorption and poor adhesion to plastic teeth. The suitability of a visible light-curing resin as a repair material, ie, its bending strength, was examined. Results were compared to those obtained with a self-curing acrylic resin. The visible light-curing resin led to repairs with lower strength.