Key Points
-
Advances in the power output of light emitting diodes (LEDS) have allowed a LED light curing unit (LCU) with an 8 mm diameter light guide tip to achieve a similar depth of cure in a camphorquinone photoinitiated composite, as a halogen LCU.
-
LEDs have long lifetimes and a more consistent output than halogen bulbs. The power density (irradiance) of an LED LCU does not have to be as high as a conventional halogen LCU to achieve the same depth of cure.
-
Blue LEDs can be used as photodetectors and may be of future use in dental radiometers.
-
When assessing the output from an LCU it is not only important to know the spectrum and irradiance, but also whether the emission is pulsed or continuous.
Abstract
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 blue LED array as a photodetector.
Design Cure depth and light output characterisation to compare the LCUs.
Setting An in vitro laboratory study conducted in the UK.
Materials and Methods The LCUs cured A2 and A4 composite shades. A penetrometer measured the depth of cure. Analysis was by one-way ANOVA, two-way univariate ANOVA and Fisher's LSD test with a 95% confidence interval. A power meter and spectrograph characterised the LCUs' emissions. A blue LED array measured the pulsed light frequency from an LED LCU.
Results Statistically significant different LCU irradiances (119 mW/cm2 to 851 mW/cm2) and cure depths (3.90 mm SD ± 0.08 to 6.68 mm SD ± 0.07) were achieved. Composite shade affected cure depth. A blue LED array detected pulsed light at 12 Hz from the commercial LED LCU.
Conclusions The prototype LED LCU achieved a greater or equal depth of cure when compared with the commercial LCUs. LEDs may have a potential in dentistry for light detection as well as emission.
Similar content being viewed by others
Log in or create a free account to read this content
Gain free access to this article, as well as selected content from this journal and more on nature.com
or
References
Bassiouny MA, Grant AA A visible light-cured composite restorative. Br Dent J 1978; 145: 327–330.
Cook WD Spectral distribution of dental photopolymerization sources. J Dent Res 1982; 61: 1436–1438.
Yearn JA Factors affecting cure of visible light activated composites. Int Dent J 1985; 35: 218–225.
Nomoto R Effect of light wavelength on polymerization of light-cured resins. Dent. Mater J 1997; 16: 60–73.
Taira M, Urabe H, Hirose T, Wakasa K, Yamaki M Analysis of photo-initiators in visible-light-cured dental composite resins. J Dent Res 1987; 67: 24–28.
Cayless MA, Marsden AM Tungsten halogen lamps. In, Lamps and Lighting. 3rd ed pp169–182 London: Edward Arnold Ltd 1983.
Barghi N, Berry T, Hatton C Evaluating intensity output of curing lights in private dental offices. J Am Dent Assoc 1994; 25: 992–996.
Martin FE A survey of the efficiency of visible light curing units. J Dent 1998; 26: 239–243.
Miyazaki M, Hattori T, Ichiishi Y, Kondo M, Onose H, Moore BK Evaluation of curing units used in private dental offices. Oper Dent 1998; 23: 50–54.
Mitton BA, Wilson NH F The use and maintenance of visible light activating units in general practice. Br Dent J 2001; 191: 82–86.
Caughman WF, Rueggeberg FA, Curtis Jr JW Clinical guidelines for photocuring restorative resins. J Am Dent Assoc 1995; 126: 1280–1286.
Shortall A, Harrington E Guidelines for the selection, use, and maintenance of visible light activation units. Br Dent J 1996; 181: 383–387.
Cobb DS, Vargas MA, Rundle T Physical properties of composites cured with conventional light or argon laser. Am J Dent 1996; 9: 199–202.
Hofmann N, Hugo B, Schubert K, Klaiber B Comparison between a plasma arc light source and conventional halogen curing units regarding flexural strength, modulus, and hardness of photoactivated resin composites. Clin Oral Investig 2000; 4: 140–147.
Round HJ A note on carborundum. Elect World 1907; 19: 309.
Holonyak Jr N, Bevacqua SF Coherent (visible) light emission from Ga(As1-xPx) junctions. App Phys Lett 1962; 1: 82.
Nakamura S, Mukai T, Senoh M High-Power GaN P-N Junction blue-light-emitting diodes. Jpn J Appl Phys Lett 1991; 30: L1998–L2001.
Nakamura S, Senoh M, Iwasa N, Nagahama S High-power InGaN single-quantum-well-structure blue and violet light-emitting diodes. Appl Phys Lett 1995; 67: 1868–1870.
Tadatomo K, Okagawa H, Ohuchi Y, Tsunekawa T, Imada Y, Kato M, Taguchi T High output power InGaN ultraviolet light-emitting diodes fabricated on patterned substrates using metalorganic vapor phase epitaxy. Jpn J Appl Phys 2001; 40: L583–L585.
Haitz RH, Craford MG, Weissman RH Light emitting diodes. In Bass M. (ed) Handbook of Optics 2nd ed pp12.1–12.39 McGraw Hill Inc 1995.
Mills RW Blue light emitting diodes - an alternative method of light curing? Br Dent J 1995; 178: 169 Letter.
Kennedy J Portable LED photocuring device. US Patent 5420768 30 May 1995.
Fujibayashi K, Ishimaru K, Kohno A A study on light activation units using blue light-emitting diodes. J Jpn Dent Pres Acad 1996; 39: 180–188.
Fujibayashi K, Ishimaru K, Takahashi N, Kohno A Newly developed curing unit using blue light-emitting diodes. Dent Jpn 1998; 34: 49–53.
Mills RW, Jandt KD LEOS IEEE Newsletter. 1998; 12: 9–10.
Whitters CJ, Girkin JM, Carey JJ Curing of dental composites by use of InGaN light-emitting diodes. Optics Letters 1999; 24: 67–68.
Mills RW, Jandt KD, Ashworth SH Dental composite depth of cure with halogen and blue light emitting diode technology. Br Dent J 1999; 186: 388–391.
Jandt KD, Mills RW, Blackwell GB, Ashworth SH Depth of cure and compressive strength of dental composites cured with blue light emitting diodes (LEDs). Dent Mater 2000; 16: 41–47.
Stahl F, Jandt KD, Ashworth SH, Mills RW Light emitting diode (LED) polymerisation of dental composites: flexural properties and polymerisation potential. Biomat 2000; 21: 1379–1385.
Powell GL, Blankenau RJ, Boutoussov D Investigation of blue LEDs for polymerization of dental composite. J Dent Res 2000; 79 Abs 2903.
Knezevic A, Tarle Z, Meniga A, Sutalo J, Pichler G, Ristic M Degree of conversion and temperature rise during polymerization of composite resin samples with blue diodes. J Oral Rehab 2001; 28: 586–591.
Kurachi C, Tuboy AM, Magalhaes DV, Bagnato VS Hardness evaluation of a dental composite polymerized with experimental LED-based devices. Dent Mater 2001; 17: 309–315.
ISO 4049:1988 British Standard Specification for Resin based dental filling materials (Class B).
Li Y, Lit JW Y Transmission properties of a multimode optical-fiber taper. J Opt Soc Am A 1985; 2: 462–468.
Miyazaki E, Itami S, Araki T Using a light-emitting diode as a high-speed, wavelength selective photodetector. Rev Sci Inst 1998; 69: 3751–3754.
Holland K LED doubles as emitter and detector. EDN 2001; 18: 108.
Harrington E, Wilson HJ Depth of cure of radiation-activated materials. Effect of mould material and cavity size. J Dent 1993; 21: 305–311.
Marston RM In, Optoelectronics Circuits Manual. 2nd ed p36 Oxford: Butterworth Heinemann 1999.
Meniga A, Tarle Z, Ristic M, Sutalo J, Pichler G Pulsed blue laser curing of hybrid composite resins. Biomat 1997; 18: 1349–1354.
DeWald JP, Ferracane JL A comparison of four modes of evaluating depth of cure of lightactivated composites. J Dent Res 1987; 66: 727–730.
Nomoto R, Uchida K, Hirasawa T Effect of light intensity on polymerization of light-cured composite resins. Dent Mater J 1994; 13: 198–205.
Acknowledgements
The authors are grateful to Dr Gordon Blackwell (Dentsply DeTrey) for providing the Spectrum composite, Mr. Paul Coughlan (CD Solutions, UK) for supplying the LuxOMax LCU, Mr Frederik Claeyssens, Mr James Petheridge and Mr James Smith (School of Chemistry, University of Bristol) for assistance with capturing the spectra.
Author information
Authors and Affiliations
Corresponding author
Additional information
Refereed paper
Rights and permissions
About this article
Cite this article
Mills, R., Uhl, A. & Jandt, K. Optical power outputs, spectra and dental composite depths of cure, obtained with blue light emitting diode (LED) and halogen light curing units (LCUs). Br Dent J 193, 459–463 (2002). https://doi.org/10.1038/sj.bdj.4801597
Received:
Accepted:
Published:
Issue date:
DOI: https://doi.org/10.1038/sj.bdj.4801597
This article is cited by
-
Bulk-fill composite in challenging cavities: conversion rate, solubility, and water absorption analysis
Odontology (2023)
-
Clinical long-term success of contemporary nano-filled resin composites in class I and II restorations cured by LED or halogen light
Clinical Oral Investigations (2018)
-
Diode-pumped solid-state laser for bonding orthodontic brackets: effect of light intensity and light-curing time
Lasers in Medical Science (2011)
-
Temperature rise and degree of photopolymerization conversion of nanocomposites and conventional dental composites
Clinical Oral Investigations (2009)
-
Evaluation of the curing depth of two translucent composite materials using a halogen and two LED curing units
Clinical Oral Investigations (2008)
