Influence of Emission Spectrum and Irradiance on Light Curing of Resin-Based Composites (original) (raw)
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Effect of LED and halogen light curing on polymerization of resin-based composites
The clinical performance of light polymerized resin-based composites (RBCs) is greatly influenced by the quality of the light curing unit (LCU). A commonly used unit for polymerization of RBC material is the halogen LCUs. However, they have some drawbacks. Development of new blue superbright light emitting diodes (LED LCU) of 470 nm wavelengths with high light irradiance offers an alternative to standard halogen LCU. The aim of this study is compared the effectiveness of LED LCU and halogen LCU on the degree of conversion (DC) of different resin composites [two hybrid (Esthet-X, Filtek Z 250), four packable (Filtek P60, Prodigy Condensable, Surefil, Solitaire), one ormocer-based resin composite (Admira)]. The DC values of RBCs polymerized by LED LCU and halogen LCU ranged approximately from 61AE1 % 0AE4 to 50AE6 % 0AE6% and from 55AE6 % 0AE7 to 47AE4 % 0AE5% %, respectively. Significantly higher DC of RBCs except Surefil and Filtek Z 250 was obtained for LED LCU compared with halogen LCU (P < 0AE05). Surefil and Filtek Z 250 exhibited no statistically significant difference values between LED LCU and halogen LCU (P > 0AE05). As a result, it was observed that the performance of LED LCU used in the study was satisfactory clinically and had sufficient irradiance to polymerize RBCs (hybrid, packable and ormocer based) at 2 mm depth with a curing time of 40 s.
Light curing of resin-based composites in the LED era
American journal of dentistry
This review thoroughly accumulated information regarding new technologies for state-of-the-art light curing of resin composite materials. Visible light cured resin-based composites allow the dentist to navigate the initiation of the polymerization step for each layer being applied. Curing technology was regularly subjected to changes during the last decades, but meanwhile the LED era is fully established. Today, four main polymerization types are available, i.e. halogen bulbs, plasma are lamps, argon ion lasers, and light emitting diodes. Additionally, different curing protocols should help to improve photopolymerization in terms of less stress being generated. Conclusions were: (1) with high-power LED units of the latest generation, curing time of 2 mm thick increments of resin composite can be reduced to 20 seconds to obtain durable results; (2) curing depth is fundamentally dependent on the distance of the resin composite to the light source, but only decisive when exceeding 6 mm...
Effects of resin composite composition and irradiation distance on the performance of curing lights
Biomaterials, 2004
This study determined the effect of using five resin composites and two irradiation distances to test the performance of dental curing lights. Three types of curing lights with similar spectral distributions, but each delivering a different power density, were used for irradiation times ranging from 3 to 60 s. Power densities were measured at 2 and 9 mm from the tip of the light guide. Five composites 1.6 mm thick and of the same shade were irradiated at 2 and 9 mm from the light guide with energy densities of 1.2-38.0 J/cm 2. The Knoop hardness at the top and bottom of the composite specimens was measured 15 min after irradiation and again after immersion in water at 37 C for 24 h. There was a linear relationship between the hardness and the logarithm of the energy density received by the composite (r 2 > 0:81). The analysis of variance showed that the composite, the side tested, the distance from the light guide, and the curing light/irradiation time combination all had a significant effect on the hardness (po0:01). Plots of the hardness at the bottom 15 min after irradiation by each light were generated for all the composites. These plots illustrated that the effects of the different curing light/irradiation time combinations on hardness were not the same for each composite. The effects of each curing light/time combination on hardness were also different at 2 and 9 mm from the light guide. In conclusion, when comparing the effects of different light sources on resin polymerization, several different composites should be irradiated at clinically relevant distances from the light guide. Using high-powered curing lights for 3 or 5 s did not deliver sufficient energy to cure the 1.6-mm thick specimens of composites used in this study.
Operative Dentistry, 2006
This study analyzed the degree of conversion, temperature increase and polymerization shrinkage of two hybrid composite materials polymerized with a halogen lamp using three illumination modes and a photopolymerization device based on blue light emitting diodes. The degree of conversion of Tetric Ceram (TC) (Ivoclar Vivadent) and Filtek Z 250 (F) (3M/ESPE) was measured by Fourier transformation infrared spectroscopy at the surface and 2-mm depth; temperature rise was measured by digital multimeter, and linear polymerization shrinkage was measured during cure by digital laser interferometry. Composite samples were illuminated by quartz-tungsten-halogen curing unit (QTH) (Astralis 7, Ivoclar Vivadent) under the following modes: "high power" (HH) 40 seconds at 750 mW/cm 2 , "low power" (HL) 40 seconds at 400 mW/cm 2 and "pulse/soft-start" (HP) increasing from 150 to 400 mW/cm 2 during 15 seconds followed by 25 seconds pulsating between 400 and 750 mW/cm 2 in 2-second intervals and by light emitting diodes (LED) (Lux-o-Max, Akeda Dental) with emitted intensity 10 seconds at 50 mW/cm 2
Clinical Oral Investigations, 2019
Objectives To evaluate light transmittance as a function of wavelength for eight composite materials and compare the transmittance for blue light produced from two curing units with different emission spectra. Materials and methods Light transmittance through 2-and 4-mm-thick composite specimens was recorded in real time during 30 s of curing using a broad-spectrum (peaks at 405 and 450 nm) and a narrow-spectrum (peak at 441 nm) LED-curing unit. The spectral resolution of 0.25 nm and temporal resolution of 0.05 s resulted in a large amount of light transmittance data, which was averaged over particular spectral ranges, for the whole measurement period. Statistical analysis was performed using Welch ANOVA with Games-Howell post hoc test, t test, and Pearson correlation analysis. The level of significance was 0.05 and n = 5 specimens per experimental group were prepared. Results Light transmittance varied as a function of wavelength and time, revealing significantly different patterns among the tested materials. Light transmittance for different parts of curing unit spectra increased in the following order of emission peaks (nm): 405 < 441 < 450. Of particular interest was the difference in transmittance between 441 and 450 nm, as these peaks are relevant for the photoactivation of camphorquinone-containing composites. A high variability in light transmittance among materials was identified, ranging from statistically similar values for both peaks up to a fourfold higher transmittance for the peak at 450 nm. Conclusion Each material showed a unique pattern of wavelength-dependent light transmittance, leading to highly materialdependent differences in blue light transmittance between two curing units. Clinical relevance Minor differences in blue light emission of contemporary narrow-peak curing units may have a significant effect on the amount of light which reaches the composite layer bottom.
Influence of different shades and LED irradiance on the degree of conversion of composite resins
Brazilian Oral Research, 2012
The aim of this study was to evaluate the degree of conversion (DC) of two composite resins with different shades that were light cured by light-emitting diodes (LEDs) of different irradiances. Specimens (5 mm × 2 mm) were prepared with a nanofilled (Filtek Supreme -A2E, A2D, and WE) or microhybrid resin (Opallis -A2E, A2D, and EBleach Low) and were randomly divided into 12 groups (n = 5 each) according to the composite resin and light-curing unit (Elipar FreeLight 2, 1250 mW/ cm²; Ultralume 5, 850 mW/cm²). After 24 h, the DC was measured on two surfaces (top and bottom) with Fourier Transform infrared spectroscopy (FTIR). Data were statistically analyzed with two-way ANOVA and Tukey test (α = 0.05). Statistical differences among the surfaces were observed in all experimental conditions, with higher values on the top surface. The microhybrid resin presented the highest DCs for shades A2E and A2D on the top surface. The LED with higher irradiance promoted better DCs. Taken together, the data indicate that the shade of a composite resin and the irradiance of the light source affect the monomeric conversion of the restorative material.
Curing effectiveness of resin composites at different exposure times using LED and halogen units
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To compare the polymerization effectiveness of two resin composites cured with a quartz tungsten halogen (QTH) lamp or a light emitting diodes (LED) unit. Filtek Z250 (3M ESPE) and Spectrum TPH (Dentsply DeTrey) resin composites were placed in 9 mm deep and 4 mm wide metallic molds and cured using the QTH light Hilux 200 (Benlioglu) or the LED unit Smartlite IQ (Dentsply DeTrey) for 20 or 40 s (three specimens per group). Measurement of depth of cure was carried out by means of a scraping technique, according to ISO 4049. The microhardness measurements were performed using a calibrated Vickers indenter (100 g load, 30 s) at depths of 0.5, 1.5, 2.5, 3.5, 4.5 and 5.5 mm from the top of the composite in the same specimens. Results were analyzed by ANOVA, Student's t and Student-Newman-Keuls tests (p<0.05). Filtek Z250 exhibited higher depth of cure and Vickers microhardness values than Spectrum TPH under each experimental condition evaluated. Depth of cure and microhardness were...
Journal of Dentistry, 2015
Coelho.Effect of different photoinitiators and reducing agents on cure efficiency and color stability of resin-based composites using different LED wavelengths.Journal of Dentistry http://dx.ABSTRACT Objectives: To evaluate the effect of photoinitiators and reducing agents on cure efficiency and color stability of resin-based composites using different LED wavelengths. Methods: Model resin-based composites were associated with diphenyl(2,4,6trimethylbenzoyl)phosphine oxide (TPO), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO) or camphorquinone (CQ) associated with 2-(dimethylamino)ethyl methacrylate (DMAEMA), ethyl 4-(dimethyamino)benzoate (EDMAB) or 4-(N,Ndimethylamino)phenethyl alcohol (DMPOH). A narrow (Smartlite, Dentisply) and a broad spectrum (Bluephase G2, Ivoclar Vivadent) LEDs were used for photoactivation (20J/cm 2 ). Fourier transform infrared spectroscopy (FT-IR) was used to evaluate the cure efficiency for each composite, and CIELab parameters to evaluated color stability (∆E 00 ) after aging. The UV-vis absorption spectrophotometric analysis of each photoinitiator and reducing agent was determined. Data were analyzed using two-way ANOVA and Tukey's test for multiple comparisons (α=0.05).
High irradiance curing and anomalies of exposure reciprocity law in resin-based materials
Journal of dentistry, 2011
Degree of conversion Light intensity Exposure reciprocity law Flowable Resin chemistry Viscosity a b s t r a c t Objectives: The aim of this work was to investigate the effect of high irradiance curing on resultant degree of conversion of 'flowable' resin composites and their counterpart higher viscosity paste materials. Methods: Five commercial flowable materials (Venus; Heraeus Kulzer, Synergy D6; Coltene, Premise; Kerr, Grandio; Voco and Gradia; GC Corp) and their counterpart higher viscosity restorative versions were tested. Specimens were cured with a halogen Swiss Master Light (EMS, Switzerland) using five different curing protocols with similar radiant exposure (18 J/ cm 2 ): 400 mW/cm 2 for 45 s, 900 mW/cm 2 for 20 s, 1500 mW/cm 2 for 12 s, 2000 mW/cm 2 for 9 s and 3000 mW/cm 2 for 6 s. Degree of conversion (DC) was measured in real time by Fourier transform near infrared spectroscopy (FT-NIRS).