Infection control and curing lights

April 1, 2012
In my life, there are some things I can depend on. As soon as I sit on the couch and say, “Ah,” someone will call.

by Noel Brandon Kelsch, RDHAP

In my life, there are some things I can depend on. As soon as I sit on the couch and say, “Ah,” someone will call. When I wear my favorite white shirt (that does not ever require ironing), I will spill a full cup of chai tea on it. If I wash my car, it will rain.

Those are just things that I plan for. One medical device that I can always depend on is my curing light. I see a lot of children and special needs adults, which necessitates rapid procedures to meet their needs while maintaining the highest level of infection control possible. My faithful curing light has always delivered consistent results.

A few weeks ago, while treating a group of frenzied third graders, I was surprised when suddenly the dependable results fell to the wayside as I reapplied sealants over and over to no avail. I had to stop what I was doing and see what had changed. There are many reasons the curing light could malfunction: Debris and resin on the tip; bulb degradation (the light can look bright but not be delivering enough power); and scratches, cracks, and fracture of the light tip.

That day I added one more item to the list: Barrier protection that is not compatible with my unit.

Testing, Testing, 1, 2, 3

Checking the light for degradation is a simple process:

1. Debris and bonding material: Check to see if there is any residual bonding material or other debris on the tip of the light guide. If there is, gently remove it, making sure you do not scratch the tip.
2. Cracks and scratches: While wearing your loupes, check to see if there are any cracks, fractures, or scratches on the end of the light guide. If there is, the light guide or, in some cases, the unit will need to be replaced.
3. Bulb degradation: The light intensity and energy output of a curing light can be checked by an inexpensive radiometer. These are either built-in to the unit or there is a hand-held device you can buy (well worth the investment). You must make sure the radiometer is compatible with the unit. The manufacturer of the curing light can tell you the kind of radiometer to use.

I have found the radiometer to be a very reliable and important tool over the years to assure the consistency of the light. It is important to use the same tip each time to check the unit and to do it at least once a month.

The readings on my unit were ideal. I thought about my protocol and remembered the one thing that I had changed. I use barrier protection on my unit between each client, but I had changed the brand of barrier protection. I put the barrier protection on and tested the unit again. I was surprised to see that the unit was not longer putting out the light necessary to cure the sealant. The decrease in output can often be countered by increasing the curing time. When it reaches a certain level, you will have to replace the unit or the light. Use the manufacturer’s instructions as your guide. I simply had to change the barrier type I was using.

Most items used in dentistry are considered medical devices and have acceptance criteria that must be submitted to the Food and Drug Administration (FDA). The FDA is responsible for regulating firms who manufacture, repackage, relabel, and/or import medical devices sold in the United States. Those considerations include infection control. The acceptance criteria for curing lights from the FDA states:

“Dental curing lights are generally provided to the user as nonsterile devices. Patient-contacting portions, such as the light tip, are intended to be disinfected or sterilized before each use. We recommend you describe the parameters for disinfection, sterilization, or both as appropriate for your device, and include the validated method, suitable chemical disinfectants for the device material type, and the cycle variables — time, temperature, pressure.”

The FDA also provides guidance on the labeling and instructions for use of medical devices as reported in “Labeling Reusable Medical Devices for Reprocessing in Health Care Facilities: FDA Reviewer Guidance.” The FDA asserts that the manufacturer’s instructions should include details on disassembly, cleaning, rinsing, disinfection/sterilization, drying, reassembly of the device, use of disposable sheathing for other portions of the device.

Every unit should have these instructions available. If they did not come with your unit, call the manufacturer and request them.

After discovering that my curing light was impacted by barrier protection, I did a search on the issue and discovered many factors that all clinicians need to be aware of when deciding their infection control protocol for curing lights:

  • Studies that evaluated the use of barrier protection with curing lights found that they can affect the quality of light being emitted from the unit but that they can be used if you evaluate them for impact (Warren DP, 2000).
  • There are exposure areas on some units that you cannot use barrier protection on that are very difficult to disinfect and cannot be autoclaved.
  • The impact of cross-contamination has been brought to the forefront in the past few years as studies have shown curing lights to be a possible source. One study was on curing units’ light guides that were routinely autoclaved, and staff and students were instructed to wipe the surfaces of the handpiece and the base unit with 70% isopropanol wipes after each patient. The study found 40% of the units were contaminated before use and 64% after use.

Clinician compliance appeared to be the major issue in this study. The biggest areas of concern were the main trigger control button, handle, and fan. The trigger button was frequently not cleaned even though the staff was instructed to do so. The handle also was found to have areas that were missed. The fan is a very difficult area to disinfect and in some units is pointed toward the mouth. Even when the unit was disinfected as recommended, the base unit was frequently contaminated (Bagg J et al. 2007). Placing the unit back on the base recontaminated the unit. This study really made me think about what we all need to be doing to have the assurance that we are not harming clients and staff.

When I chose my unit, I looked for one that did not have a fan, but dissipated the heat into the handle like an Apple computer. I found an activating device that was smooth instead of a trigger that is difficult to clean. I wanted a cordless model because I find cords difficult to work with and keep free from cross-contamination. My charger is no longer kept on the counter and is cleaned between each client since it cannot be barrier protected and still charge the unit. I only charge the unit between clients. Always find out what the infection control steps are before buying the unit.

Manufacturer’s infection control procedures

  • Sterilization: Many units require sterilization of the light guide. You can buy multiple light guides in some cases. Follow the manufacturer’s recommendations for sterilization.
  • Disinfection: Follow the manufacturer’s recommendations for the disinfecting directions to use on the unit. Utilize this at the start of the day, after each patient, and at the end of the day. Some units will require you to submerge the light guide, according to the instructions. It is important to use barrier protection on areas that will enter the mouth because there will be chemicals on these areas. Many units will require barrier protection and disinfection because of the way the product is manufactured. For example, fans cannot be covered with barrier protection but are an area where contamination can be spread. You must be careful with disinfection solutions in this area because of electrical wiring and the fan action.
  • Barrier protection: Barrier protection has proven to be a very effective measure in prevention of cross-contamination that limits exposure to chemicals. The 2003 Centers for Disease Control and Prevention’s (CDC) Infection Control Guidelines for Dental Healthcare Settings emphasizes that barrier protection of surfaces and equipment can prevent contamination of clinical contact surfaces, but it is particularly effective for those that are difficult to clean such as curing lights. After checking to see if the material for barrier protection is compatible, use new barrier protection for each patient. Be careful not to contaminate the area under the barrier protection when removing. If you contaminate the area, simply disinfect and replace barrier.

Knowing that the phone is sure to ring, I now take it with me to the couch. My friend made me a bib to match my shirt, and I have stopped washing my car. Mechanical devices that we can depend on in dentistry require us to continue to evaluate research and identify manufacturer’s findings for proper infection control. Following those procedures will allow us to assure consistent dependable results.


Bagg J, Smith AJ, Hurrell D, McHugh S, Irvine G. (2007) Sterilisation of re-usable instruments in general dental practice. British Dental Journal 202(9).

Warren DP, Rice HC, Powers JM. Intensity of curing lights affected by barriers. J Dent Hyg., 2000 Winter;74(1):20-3.

Noel Brandon Kelsch, RDHAP, is a syndicated columnist, writer, speaker, and cartoonist. She serves on the editorial review committee for the Organization for Safety, Asepsis and Prevention newsletter and has received many national awards. Kelsch owns her dental hygiene practice that focuses on access to care for all and helps facilitate the Simi Valley Free Dental Clinic. She has devoted much of her 35 years in dentistry to educating people about the devastating effects of methamphetamines and drug use. She is a past president of the California Dental Hygienists’ Association.

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