I’m Beginning to See the Light

Paul Feuerstein, DMD


The bulb in my trusty old Pelton Crane Light Fantastic went out. Checking around the office, I found a little white box that contained a wrapped bulb and what looked like a cheap pair of pliers. Instructions said to pry the socket prongs apart and carefully remove the expired bulb, being sure the switch was in the off position. (No matter how many times I turned that light on and off, without the bulb in, I was not totally sure if it was off.) Then, without touching the new bulb, wriggle it in with one hand while holding the prongs apart with the “pliers.” Those of you who have had this experience know about wrapping a 2 x 2 around the bulb and struggling to snap the new one in at the exact moment you release the pliers. Luckily, this is not a daily task (but indeed a memorable one). In addition, most lights have a glass parabolic reflector that gets quite hot and often burns through the reflective coating. Reflector replacement can be done by the dentist or staff, but this is always is a tense process. And how many times do you have to tell patients this: “Do not touch the hot light!”

In another era, those of us “early adopters” who used headlights had a large fiber-optic box with a hot bulb and an expensive, heavy black cord that attached to the headlight. How many times did you try and walk away from the chair, almost pulling a muscle in your neck?

Figure 1. DentalEZ’s everLight.
Figure 2. A-dec’s LED light.
Figure 3. Ivoclar Vivadent’s Bluephase Style curing light.

Thankfully, these scenarios have come to a conclusion. When you look at new chair lights and headlights, the bulbs are gone, replaced by light-emitting diodes (LEDs). These also show up in curing lights, laser guiding lights, and other equipment. And when you go to a retail store for bulbs for your home or office lighting, you are now told that they don’t even make the old 60W incandescent bulbs; you now have to spend $5 to $30 for a new LED or compact fluorescent light (which is now falling in disfavor). For dental use, the great thing about LEDs is that each one can be programmed to emit a specific frequency from the light spectrum. (Remember ROY G BIV?) For general lighting from the ceilings or lamps, we want “full-spectrum, color-corrected light.” There are a few fluorescent bulb companies that manufacture these for existing ballasts like Vita-Lite, although green offices are shying away from all fluorescents. We must be aware that composites and bonding agents are sensitive to specific frequencies, and herein lies a problem; the new overhead chair lights using LEDs are full spectrum, which helps in shade matching as well as giving excellent directed light. The composites and bonding agents we use will set at the blue wavelength, which is contained in these overhead LEDs. Thus, the materials will begin to cure immediately. To overcome this, all new chair lights have a “curing” setting where the full-spectrum LEDs are shut off, and a set of orange lights come on. You can see these clearly in the new lights and continue with your procedure. Also, since there is no need for the reflectors, design engineers have devised some very slick “space age-looking” lights. They are compact and lightweight, and many come with a guarantee of 7-plus years on the bulbs.

With respect to the curing frequencies, we should be aware of a little chemistry. Camphorquinone is the photo initiator for most of the materials sold today, and they photopolymerize with blue light. In former times, butyl hydroxytoluol or lucirine was used, needing ultraviolet light for curing as well as other photo initiated chemicals. And there are other chemicals around too. Initially, Ultradent Products gave us the Ultralume (now VALO, covering 395 to 480 nm), and Ivoclar Vivadent offered Bluephase (now Bluephase Style, covering 385 to 515 nm). These along with other models use multiple frequency LEDs to cover all products.

But frequency is not the only thing; intensity is important too, and with time, the LEDs as well as the fiber-optic “pipes” can degrade and lower the light output. (Note that some, like VALO, have the LEDs right in the tip.) This has to be constantly monitored, or you will have partially cured composites. Kerr Corp recently launched checkMARC (checkmarc.net), a service that allows offices to determine if lights are working properly. All magnification manufacturers have incorporated this LED technology into the once heavy, bulky, and sometimes tethered lights. Independent companies have headlights that will fit all loupes. One, ultralightoptics.com, has a light that weighs a mere 3 g. Again, be careful when bonding and placing composites. All of these new headlights have a drop-down orange filter to use during that process.

Current research shows that certain oral pathogens can be killed by the blue frequency between 400 and 470 nm. This could lead to in-office or even at-home treatment devices. There are already units being sold in Europe called Photo-Activated Disinfection devices that are capable of doing this.

There are other areas where LEDs have appeared, including in our automobiles, again thanks to low power, low heat, and long life. (For more technical information, I will post details on our website, dentistrytoday.com.) And finally, LEDs are more environmentally friendly and will give you a greener office. On this topic, visit ecodentistry.org; it might just be your first step.