Dental curing lights come in handy for a range of dental applications, from direct restorations to whitening procedures. It’s hard to imagine modern dentistry without them. In fact, a recent industry report predicts that the global dental curing light market will be worth more than $197 million by 2022. 1Research and Markets. Global Dental Curing Lights Market 2018–2022. Available here. Accessed October 2, 2018.
Unlike their self-curing predecessors, light-curing composite materials give clinicians complete control over working time. The polymerization process only begins when composites are subjected to a particular wavelength of light that activates a photoinitiator — most commonly, camphorquinone. 2Santini A, Gallegos IT, Felix CM. Photoinitiators in dentistry: a review. Prim Dent J. 2013;2:30–33.
But for successful light curing, clinicians must verify what photoinitiators are in their materials, and ensure that their curing lights are capable of activating them. 3Santini A, Gallegos IT, Felix CM. Photoinitiators in dentistry: a review. Prim Dent J. 2013;2:30–33. 4Strassler HE. The Physics of Light Curing and its Clinical Implications. Available here. Accessed October 2, 2018.
To this end, at least a couple of values are important to keep in mind. A curing light’s average irradiance intensity, or output, is expressed as miliWatt per square centimeter (mW/cm2). Typically ranging from 1200 to 3200, this value impacts duration, polymerization reliability, and depth of curing.
But especially critical for matching the necessary activation level for a photoinitiator is the spectral emission, or wavelength, expressed in nanometers (nm). For example, camphorquinone is most commonly activated by a blue light emitting between 400 and 500 nm. 5Soares CJ, Rodrigues MP, Oliveira LR, et al. An evaluation of the light output from 22 contemporary light curing lights. Braz Dent J. 2017;28:362–371.
Types of Curing Lights
The four primary curing light technologies include plasma arc, argon laser, quartz-tungsten halogen and light-emitting diode (LED). The last two are the ones most likely to be found in most contemporary dental practices.
Quartz-tungsten halogen units produce light by transmitting a current through a tungsten filament inside a quartz bulb containing halogen gas. They offer a broad light spectrum, from around 380 nm to 551 nm. 6Namrata M, Ganapathy D. Light cure devices. Int J Orofacial Res. 2017;2:37–39. Because quartz-tungsten halogen lights generate heat, they require the use of fans. This adds to their bulkiness. In addition, their cure rate is reportedly slow, they require power cords, and their output diminishes over time. 7Stone R. Cure for the common composite. Mentor. 2017;8(5):16-18, 20-21
LED curing lights produce light through doped semi-conductors. Due to a narrower light wavelength range, between 395 and 500 nm, the LED beam is said to be more effective as it more closely meets the wavelength requirement of the photoinitiator. They also appear to have a statistically significant edge in curing nanohybrid composites when used with soft-start mode, with respect to resulting hardness and depth of cure. 8Roy KK, Kumar KP, John G, et al. A comparative evaluation of effect of modern-curing lights and curing modes on conventional and novel-resin monomers. J Conserv Dent. 2018;21:68–73.
Because LED units produce little heat, the need for fans is eliminated, so the units can be lightweight, streamlined and cordless.8 For such reasons, LED curing lights have been gaining market share in recent years. It’s a trend that is expected to continue due to continued improvements in this technology and the fact that they don’t consume as much energy as other curing light technologies. 9Research and Markets. Global Dental Curing Lights Market 2018–2022. Available at:
https://www.researchandmarkets.com/reports/4541182/global-dental-curing-lights-market-2018-2022. Accessed October 2, 2018.
Newer LED units offer increased levels of irradiance, some delivering more than 5000 mW/cm2 for fast and reliable polymerization and deeper cures, in some cases up to 6 mm. Multispectral LED curing lights have become available, offering wavelengths as high as 500 nm and as low as 395 nm to accommodate a wider range of materials.
Safely Enhance Visibility
Regardless of which type of curing light is to be used, as dental practitioners know all too well, when placing hydrophobic composite materials, good moisture control and visibility are key. For best results, isolation systems, such as Isolite, can give clinicians the extra edge they need, not only in soft-tissue retraction, but also in moisture control through hands-free suction before and during curing.
Just as the right light at the right time can bring about a stellar cure, the wrong light at the wrong time can really mess things up. For example, good visibility of the field of operation, and the oral cavity as a whole, is a restoration-placement necessity. But this can present a bit of a conundrum when clinicians are placing light-cured materials. If white light is used for illumination, there is a risk it might inadvertently initiate the polymerization process.
The Isolite 3 dental isolation system solves this problem. In addition to its bright white light, it also offers excellent illumination via a true amber light cure-safe mode. This allows clinicians to safely place composite restorations without fear that the material will accidentally “go off.” A win-win on so many levels.
And while designs continue to be streamlined, new curing lights are also offering multiple curing modes, and faster cures, in addition to white light that can be used in transillumination. Indeed, they are becoming the magic wands of modern dentistry.