Composite resin is a widely-used direct tooth coloured restorative material. Photoactivation of the polymerisation reaction can be achieved by visible blue light from a range of light sources, including halogen lamps, metal halide lamps, plasma arc lamps, and Light Emitting Diode (LED) lights. Concerns have been raised that curing lights ...

The purpose of this study was to determine the effectiveness of polymerization in the newly introduced blue light emitting diode (LED) (Experimental, SNU, Korea), and plasma arc curing (PAC) (Apollo 95E, Elite, DMD, USA) compared with conventional halogen lamp (Spectrum 800, Dentsply, USA). Various irradiation time with fixed intensity of ...

This study compares commercially available light-emitting diode (LED) lights with a quartz tungsten halogen (QTH) unit for photo-activating resin-based composites (RBC). Shrinkage strain kinetics and temperature within the RBC were measured simultaneously using the 'deflecting disc technique' and a thermocouple. Surface hardness (Knoop) at the bottom of 1.5-mm thick RBC ...

Life usually gets simpler, but in the case of photocuring dental restorative materials, just the opposite is true. Confusing and contradictory barrages of clinical claims have been made with the ever-growing variety of light-curing sources available today. Often, laboratory research or clinical studies related to these systems are lacking prior ...

OBJECTIVE: To test the hypothesis that a prototype LED light curing unit, (LCU), a commercial LED LCU and a halogen LCU achieve similar cure depths, using two shades of a camphorquinone photoinitiated dental composite. To measure the LCUs' outputs and the frequency of the LED LCU's pulsed light, using a ...

Ortholux XT is a high-intensity light source emitting filtered visible blue light in the 400- to 500-nanometer range for polymerization of visible-light-cured resins. The Ortholux handpiece comes with a portable power supply, a light-intensity check in the power supply, a spare lamp, an eyeshield and a mounting kit. The handpiece ...

Light-cured, resin-based composite is an integral part of esthetic and restorative dentistry. This article reviews the performance and limitations of 4 types of curing lights and predicts that curing lights of the future will use light-emitting diode (LED). Currently, LED curing lights are not as powerful as plasma arc curing ...

OBJECTIVE: To test the hypothesis that operator experience influences the efficacy of light curing in a typical posterior intra-oral location. To investigate whether short cure cycles affect performance. DESIGN: A cross-sectional single-centre study designed to assess the efficacy of experienced and inexperienced operators when undertaking simulated intra-oral curing. SETTING: An ...

Commercially available light-emitting diode (LED) light-curing units recently have been introduced to the dental products market. No published studies have evaluated the adequacy of cure of commercially available LEDs. The purpose of this study was to compare the shear bond strength of orthodontic brackets bonded to teeth with conventional halogen-based ...

Light curing of composite resin material beneath orthodontic brackets is common in clinical orthodontics. Experiences with composite resins and high-intensity lights indicate some advantages to staged curing of the composite. In this study, the shear/peel bond strength of orthodontic brackets bonded to bovine enamel and cured with a pulsed xenon ...

OBJECTIVES: The goal of this study was to assess the reduction of polymerization contraction stress of composites during a two-step light-activation process and to relate this reduction to the process of polymerization shrinkage and specimen thickness. METHODS: Three test procedures were performed to compare two-step light-activation with delay with one-step ...

This study evaluated the influence of radiation intensity on polymerization of a resin-based composite (RBC) and compared the influence of guidance of shrinkage vectors vs irradiation at reduced light intensity on the marginal seal of Class V RBC restorations in vitro. The degree of cure was studied indirectly by measuring ...

Groups of samples of a light-activated resin composite were exposed, using a 3-step pulse-delayed protocol, to a plasma arc unit. Further groups were exposed with the light-curing guide positioned at increasing distances from the composite surface. The pulse-delayed protocol yielded a progressive increase in microhardness number at the end of ...

OBJECTIVE:To test the hypothesis that operator experience influences the efficacy of light curing in a typical posterior intra-oral location. To investigate whether short cure cycles affect performance. DESIGN:A cross-sectional single-centre study designed to assess the efficacy of experienced and inexperienced operators when undertaking simulated intra-oral curing. SETTING:An in vitro laboratory ...

The availability of light-curable resin systems has led to the development of a variety of technologies for producing the light necessary to cure them. Light, being electromagnetic radiation, is comprised of a wide spectrum of energies including ultraviolet, visible, and infrared. Each wavelength region of light has different characteristics in ...

This article describes the prosthetic rehabilitation of small maxillary lip and maxilla defects with a lip prosthesis attached to an obturator. The definitive obturator prosthesis was designed with 3 plastic ball attachments on the labial surface that provided adequate retention for the lip prosthesis. The thin margin of the lip ...

Instrumental neutron activation analysis has become a standard technique for the study of the production and distributional patterns of archaeological pottery. Questions once framed within the context of long distance exchange are now focused on issues of subregional and even intrasite levels. The increasing specificity at which these questions are ...

Everyday improvements in components and characteristics of composite materials have induced faster development of curing units. Besides standard halogen curing units and soft-start photopolymerization light sources, some experiments with argon and pulsed laser light and low intensity blue superbright light emitting diodes have been made. On the other hand, rapid ...

This in vitro study evaluated the wear resistance of resin composite polymerized using four different light-curing systems. For this, a well-defined cylindrical cavity preparation (4.0 mm in diameter x 3.0 mm in depth) was made in a ceramic block (n=4 per material/light condition). Uncured material, either a universal hybrid composite ...

The objective of this study was to evaluate the degree of conversion and temperature rise in three different composite materials when illuminated by an experimental light source [blue superbright light emitting diodes (LEDs)] and compared with plasma light and traditional photopolymerization unit. The degree of conversion and temperature rise were ...

Effects of pig birth (first 3-wk period) and rearing environments on growth and muscle quality characteristics of loins were evaluated in three experiments over seasons in west Texas and central Missouri. Housing systems included indoor slatted-floor buildings, indoor deep-bedded buildings, outdoor housing on dirt, and outdoor housing on alfalfa pasture. ...

OBJECTIVES: To determine the release of leachable components from resin based composites (RBC) after plasma arc vs. standard or soft-start halogen curing. METHODS: The tested RBC were the fine hybrids Herculite XRV (Kerr), Solitaire 2 (Kulzer) and Z250 (3M), the micro-fill Silux Plus (3M) and the polysiloxane-containing Definite (Degussa). The ...

Response to stimulus is a basic process of living systems. Based on the lessons from nature, scientists have been designing useful materials that respond to external stimuli such as temperature, pH, light, electric field, chemicals and ionic strength. These responses are manifested as dramatic changes in one of the following: ...

Light usually diffracts in all directions when it emerges from a subwavelength aperture, which puts a lower limit on the size of features that can be used in photonics. This limitation can be overcome by creating a periodic texture on the exit side of a single aperture in a metal ...

The purpose of this research was to determine the depth of cure of light-activated composites in relation with different clinically relevant parameters. A Raman spectroscopic method has been used. The measurement of cure is made on a relative basis by comparing the vibration band of the residual unpolymerized methacrylate C=C ...

At this time, all the light-curing technologies on the market work adequately when used as directed by the manufacturers. The trend in the profession is to accept faster curing of resin-based composite. I agree completely. I have been using fast curing lights for many years, and I do not see ...

The light-attenuating effects of enamel on the mechanical properties of light-cured composite resins were evaluated using simple experimental filters. Three filters were designed to simulate the light transmittance characteristics of 0.5, 1.0, and 1.5 mm thick human enamel. The Knoop hardness numbers (KHN) and the elastic modulus in transverse tests ...

OBJECTIVE: A novel laser interferometric method for monitoring linear polymerization shrinkage in dental restoratives is demonstrated. METHODS: The experimental apparatus consists of a low power Helium-Neon laser, a home-built Michelson interferometer, amplified photodiode detectors, and a computer data acquisition system. The feasibility of using interferometry to measure linear shrinkage was ...

Successful curing depends directly on many factors of which the most important is the correct functioning of the curing unit to emit light of sufficient intensity and quality. If the contribution of any of these factors is at a less than adequate level, the light-sensitive materials will not polymerise completely, ...

The objective of this study was to evaluate the effects of different cure times, light sources, and light guides on shear bond strength of orthodontic brackets bonded with Transbond XT (3M Unitek, Monrovia, Calif) to bovine enamel. Specifically, the Power Slot (Reliance Orthodontic Products, Itasca, Ill) light guide was placed ...

Curing lights are used to cure light-sensitive dental materials in clinical situations that range from small, easily accessible restorations to larger ones that are more difficult to access. The degree to which these materials cure depends on the intensity and quality of light to which they are exposed and the ...

Obturator prostheses are typically large, and their weight and size are often important design factors. This article describes the fabrication of an obturator prosthesis with a titanium framework and visible light-polymerized denture base resin. It is speculated that these low-density materials may produce prostheses lighter than similar ones made with ...

BACKGROUND: Several factors control the light curing of a resin-based composite: the composition of the composite, the shade of the composite, the wavelength and bandwidth of the curing light, the distance of the light from the composite, the intensity of the curing light and the irradiation time. The authors investigated ...

This study evaluated the effectiveness of light-curing (heat conversion) vs no light-curing (no heat conversion) of a 35% hydrogen peroxide in-office tooth whitening system. Twenty patients with sound medical history (without tooth sensitivity) participated in this randomized, parallel clinical evaluation. Only six maxillary anterior teeth with discoloration and a tooth ...

If the potential of a scalar field phi which currently provides the "dark energy" of the Universe has a minimum at phi = -M(0)(4)<0, then quantum-mechanical fluctuations could nucleate a bubble of phi at a negative value of the potential. This bubble would then expand at the speed of light. ...

BACKGROUND: Light-emitting diode, or LED, technology provides certain advantages over halogen-based light polymerization of resin-based composites. The authors investigated the adequacy of cure of LED light-curing units, or LCUs. METHODS: The authors used two halogen-based light-curing units (Optilux 400 and 501, Demetron Research Corp., Danbury, Conn.) and two commercially available ...

OBJECTIVE: To evaluate the effects of a light source, polymerization time and storage time on the microhardness and wear of pit and fissure sealants. METHODS: Five commercial pit and fissure sealants (Fissurit F [FF], Teethmate F1 [TF], Apollo Seal [AS], Concise [CC], and Ultraseal XT Plus [US]) were used. Specimens ...

Variations in the isotopic composition of some components in primitive meteorites demonstrate that the pre-solar material was not completely homogenized, nor was it processed at sufficiently high temperatures to erase the signatures of the diverse stellar sources. This is in accord with the observation that accretion disks of young stellar ...

Five visible light-cured composite resins used as restoration or adhesive materials in dentistry, were irradiated with high energy plasma light (1300 mW/cm2), and contraction, rate of contraction, irradiation-induced temperature were analysed. A comparison was carried out with the same materials irradiated with a conventional halogen light (400 mW/cm2). The exposure ...

PURPOSE: To compare the Knoop hardness of different thicknesses of resin composite irradiated using either a plasma arc curing (PAC) light, or a quartz tungsten halogen (QTH) light. MATERIALS AND METHODS: A 2.5-mm diameter hole was drilled through the center of 2, 3, 4, and 5-mm thick discs of enamel ...

Many chemical reactions are associated with the emission of electromagnetic radiation in the form of heat and/or light. This paper reviews the categories of materials that produce visible light when they react, either spontaneously upon contact with air or upon ignition, as well as the processes by which such materials ...

The use of composite resin restorations in posterior teeth has increased considerably in the past few years. Specific composite resins for posterior teeth, as well as new operative techniques, have been developed to overcome some clinical difficulties. The present article describes a new technique to reconstitute the interproximal contour and ...

This study evaluated the effectiveness of the plasma arc curing (PAC) unit for composite curing. To compare its effectiveness with conventional quartz tungsten halogen (QTH) light curing units, the microhardness of two composites (Z100 and Tetric Ceram) that had been light cured by the PAC or QTH units, were compared ...

PURPOSE: The purpose of this study was to compare the curing efficiency of three commercially available light-emitting diode (LED)-based curing lights with that of a quartz tungsten halogen (QTH) curing light by means of hardness testing. In addition, the power density (intensity) and spectral emission of each LED light was ...

PURPOSE: This study compares the percentage decrease in power output of light-emitting diode (LED) and quartz-tungsten-halogen (QTH) curing devices at different distances between the light guide tip and a radiometer. MATERIALS AND METHODS: Three LED curing devices (Elipar FreeLight/3M ESPE, Luxomax/Akeda, e-Light/GC) were compared to two QTH curing devices (Elipar ...

AIM: To ascertain if interpretation of radiographs by holding them up to a window rather than using a light viewing box has led to underdetection of clinically significant radiographic abnormalities. MATERIALS AND METHODS: Twenty members of staff were selected randomly. They were divided into two group i.e., ten house offers ...

PURPOSE: To improve the usefulness of the Hirschberg Corneal Light Reflection Test (CLRT), using a photogrammetric technique independent of the size of the pupil, and to devise an easily remembered sequence of numbers corresponding to the fractional displacement of the reflection in various approximate angles of esotropia. METHOD: Photographs (slides) ...

This study investigated the influence of pulse activation and soft-start polymerization regimens on the post-gel shrinkage of a visible light-activated composite resin (Z100). A light-cure unit (BISCO VIP) that allowed for independent command over time and intensity was used. The six light-curing modes that were examined include: Control (C)-400 mW/cm2 ...

STATEMENT OF PROBLEM: Variations in light-polymerizing parameters, such as light intensity and light-to-material distance, may affect the physical characteristics of polymerized resin. PURPOSE: The purpose of this study was to characterize the relation between total light energy and the final hardness of 4 composites polymerized under varying conditions. MATERIAL AND ...

Magnetic and toroid formfactors as well as the radiation intensity for a linear oscillating current flowing through a (knotted) toroidal spiral with a fractional number n=q/p(p,q=integers) of turns of winding are calculated. Some topological properties of such current lines are analyzed by studying the isotopic deformations when the ratio epsilon ...