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.