The ideal light-curing unit should have a broad emission spectrum, sufficient light intensity, minimal drop off of energy with distance, multiple curing modes, sufficient duration for multiple curing cycles, durability, a large curing footprint, and be easily repairable.

The objective is sufficient polymerization, and so the light needs to be collimated, which is critical for focusing the light at greater distances. Increased light exposure ensures increased depth of cure, increased conversion or polymerization, and increased hardness. Inadequate light intensity or energy leads to inadequate polymerization and increased bacterial colonization, which can reduce bond strength, decrease retention, and result in inferior physical properties, excessive wear, bulk fracture, color instability, and increased microleakage, which in turn will result in secondary caries, staining, and postoperative sensitivity.

One must remember that when light intensity is measured by itself at a specific depth, this has no correlation to what happens when a composite is placed at that depth, because, as the light passes through composite, the light is attenuated drastically depending on the filler type, filler loading, hue of the composite, refractive properties, opacity, and translucency.

In order to decide how long it takes to adequately cure a composite, one has to look at the energy density used, which is the irradiance of the light multiplied by the time of application (measured in Joules). The distance from the composite surface drastically affects the power generated. The collimation of the light, or how much light is wasted when not focused forward, can drastically affect the power at depth. As mentioned earlier, the wavelengths and the type of composite affect the efficiency of light-curing. The bottom line is that it takes about 17 J/cm2 to 20 J/cm2, which equates to 20 seconds with a 1,000-mW/cm2 light energy to obtain the optimum degree of polymerization of a composite. Independent of the technique being used and the care the clinician takes during the process, insufficient irradiance can lead to inadequate polymerization even after the recommended curing times. We know that turbo tips that channel the light suffer from poor energy at distance and in unique situations, such as very deep cavity preparations, trans-tooth curing, opaque composites, or the curing of resin cements through indirect ceramic veneers, onlays, or crowns. For these cases, increased curing time is mandatory.

The new multi-spectrum LED lights emit energy at the absorption spectrum for camphorquinone, Lucirin TPO, and phenylpropanedione, thus curing all composites14 and are the current state-of-the-art for clinical practice. However, the current market selection is limited. In the desired category of broadband curing lights, VALO with its patented technology delivers more power than any other dental curing light. It uses a thermally conductive layer to distribute heat from the LED to the aluminum body of the curing light, eliminating the need for a cooling fan.

Using highly efficient LEDs with a thermal management system that drives the chip at only 30% of its available capacity, the chip runs substantially cool, while maintaining consistent performance even in the most challenging and demanding curing needs. The light has four LED curing chips with a range of 395 nm to 480 nm, thus effectively curing all composites. The light has rhodium-coated reflectors that ensure better collimation of the light, and an internal glass lens that will not discolor to affect light transmission, nor create heat generation due to reflection. VALO produces a more uniform and larger area of curing than any of the other broadband lights. The standard mode of 1,000 mW/cm2 has 5-, 10-, 15-, and 20-second curing cycle times, with the high-power tack mode at 1,400 mW/cm2 having curing times of 1, 2, 3, and 4 seconds.

Composite and adhesive dentistry have seen an explosion both in their use and in the science that has allowed them to become the most commonly placed restorative materials in a huge number of practices. Careful science and research from multiple sources has allowed tooth-colored materials to move from the realm of “pretty but unpredictable” into the category of “what I reach for first” for a large number of doctors.

There are several factors that can affect the longevity and overall success of bonded restorations. Among these factors are things such as: biologic contamination, oil contamination, voids on pulpal floor, incomplete bonding and over etching.

While one of the factors that has really changed in recent years is dental curing lights, and I don’t think they are factored in as heavily in the success or failure of bonded restorations as they should be.

Curing lights, and the science behind them, have seen amazing growth and changes in the last few years. Let’s take a look at some of the amazing things that have happened and why you should be aware of them.

We have seen an explosion in the amount of technology and the resulting equipment required to deliver it. If you’re lucky enough to have built a new office lately, you’ve been able to plan for this and avail yourself of more counter space. However, for many of us, that’s just not an option. This means the amount of countertop real estate is decreasing for the majority of offices.

Most of today’s composites use camphorquinone as the photoinitiator. This chemical, often referred to as CPQ, requires a specific wavelength (color) of light to trigger it into starting polymerization of the composite resin. Because LEDs can be fine-tuned to produce just a specific wavelength or range of wavelengths, these curing devices now produce light where every photon that’s produced can be used in the curing process. This translates to better and more efficient curing. Many non-LED curing devices, such as fast halogen lights, produce lots of photons that are wasted because they are outside the range used by CPQ.

LEDs are incredibly energy efficient. This translates into the dental equipments using less electricity than a device that uses some type of bulb with a filament. Interestingly enough, a bulb with a filament loses 90% of its energy as heat and generates only 10% as light.

Because LEDs are much more energy efficient, they don’t require nearly as much power. The result is that these devices can be powered by batteries rather than by AC current. This means a smaller footprint (see above), no cords, and being friendlier to the environment.