3 Things You Should Check on Your Curing Light Today

Terri Lively

The tools you use in the operatory enable you to provide the patient care and productivity that you need to do restorative dentistry. Your curing light is an essential part of this workflow and should work in perfect order to keep things moving and curing in the chair. However, many practices are so busy that they have let their light maintenance slide, which can lead to less than an optimal performance by your light and problems with restorations down the road.

Maintenance of your curing light is vital to your restorative dentistry. Today, we take a closer look at what problems can occur with insufficient curing, how the light contributes to the problem, and what things you should check on your light today to avoid them.

The Problems of Insufficient Curing of Materials

Multiple problems can occur when a curing light is not operating at top performance. To start with, polymerization of light-cured composite restorative materials depends on the curing light activating the photoinitiators in the dental composite resin materials. If the curing light doesn’t do the job, insufficient polymerization can increase water sorption and solubility of the material.1 When water sorption and solubility increased, the outcome for the restoration is decreased mechanical properties and longevity.2

Increased water sorption and solubility are not the only problems that can occur when your material is not cured correctly. Some research indicates that curing techniques could affect polymerization shrinkage in restorations. Moreover, in addition to hampering the mechanical properties, insufficient curing could reduce biocompatibility, increase the residual monomers, and change the material’s performance because of a higher chance of surface staining and marginal leakage.

What the Curing Light Has To Do With It

According to the Journal of Clinical and Experimental Dentistry, a few things go wrong with the curing light that leads to these terrible outcomes. The curing light affects polymerization with its:1

  • Wavelength output and intensity of irradiance: The International Standards Organization (ISO) 4049 standard is 300 mW/cm2 with a wavelength bandwidth of 400-515 nm (nanometers) on the tip.
  • Duration of exposure to the light: These vary based on the material and the depth of the preparation, so follow the manufacturer’s instructions here.
  • Position in relation to the cured materials: The two essentials here are to have the light as close as possible to the material without touching it and parallel to the surface. 

Curing technique with the light is a factor here, but the curing light’s make, model, and age influence each of these factors. Moreover, the maintenance program you undertake affects them, too. 

What 3 Things Should You Check on Your Curing Light Today?

Many curing lights do not receive regular maintenance. Moreover, not all clinicians check the same things. Consider the survey responses from October 2019 regarding maintenance and monitoring of their light units from the Journal of the American Dental Association’s (JADA) ADA Clinical Evaluators (ACE) panel:1

  • 67% checked the light output; only 18% recorded their findings, and only 3% checked the light output daily, followed by 19% weekly 
  • 72% checked and cleaned the light tip ends to remove debris
  • 32% check the batteries on cordless units
  • 30% replaced batteries that showed a low charge capacity
  • 30% test cured composite samples regularly

Maintaining your curing light is essential, starting today. Here are 3 things you should check on your dental curing light today:

#1: Light Output

The output of your light is essential to the curing process. Unless you just checked it, there is no way of knowing what the irradiance is. Also, the light output decreases the more use the curing unit gets, so if you haven’t checked it lately with a radiometer, you might be surprised at what your light irradiates now versus the last time you checked it. 

Many dental professionals will prolong exposure time to account for any discrepancies in light output. However, per the Journal of Clinical Experimental Dentistry (JADA), you can’t make up for insufficient radiation by curing longer. Instead, the authors suggest using a digital radiometer to measure the intensity of the curing light and using those readings to determine if the light needs to be fixed or replaced.1

JADA also recommends monitoring and recording the light output of their curing lights with a radiometer to ensure your light is working properly. While JADA says it doesn’t matter which radiometer you use, it is essential to use the same one in subsequent testing to see if there is a change in the output.1 

The British Dental Journal reiterates the importance of checking your curing light’s output with a radiometer, adding that it is essential to record of the readings. In particular, the authors say you should have the value from when the light was new and compare it with the unit output before each clinical session. When you see a reduced output, they recommend increasing the exposure time.1

#2: The Light Tip

Jeff Lineberry, DDS, FAGD, a lecturer and private-practice dentist in Mooresville, NC, says it is essential to check the tip of the curing light. If the curing tips are cracked, chipped, or have resin stuck to them, it can hinder curing. 

“When the tip has debris stuck on it, it distorts the light and wavelength, which impacts the output of the light and its curing abilities,” Dr Lineberry explains.

Dr Lineberry and the team check their VALO LED light once a day. If they find resin on the tip, they carefully clean it off with a scaler. Dr Lineberry also recommends sleeves and protective covers for the tip of the light, usually produced by the manufacturer of the light, to prevent the resin from getting stuck on the tip. However, infection control barriers could decrease light output by as much as 10 percent, so bear that in mind when curing.1

Dr Lineberry also recommends using an outside-in approach to avoid getting debris on the light, meaning the team begins the curing process further away from the surface of the unpolymerized materials to harden the surface and then move in closer to ensure they get the depth of cure the need underneath the surface.

“I’ll start it off that way for maybe the first half a second to a second at the most and then get it closer,” Dr Lineberry says. “Being away from the surface gives the material a chance to harden, so if you do touch it with the tip when curing, it doesn’t stick.”

The British Dental Journal says that curing lights without clean and undamaged light source tips should not be used. The authors also suggest checking the light immediately after using it with a patient to ensure no bonding agent or composite is there and to remove them immediately if there is. If the light tip is damaged, the authors say replacing the unit or sending it in for repair.

Moreover, the tip size is crucial. Blue Light Analytics says that when the tip isn’t large enough to cover the resin area if the tooth profile is uneven or hot spots where curing is more intense, it affects curing abilities. If your light tip is small and the surface to cure is large, Blue Light Analytics recommends overlapping the curing areas for comprehensive curing. Blue Light Analytics also recommends weekly testing of all curing lights to improve the results you get from restorations.1

#3: Beam Profile

How the light distributes from the tip of your curing light is called the beam profile. Blue Light Analytics says that some lights emit uniform beam profiles while others have “hot spots,” or areas where the light has a higher concentration of irradiance. The risk is that materials cured by the areas of less concentration in the beam profile may not receive enough wavelength and intensity to cure properly.2

The Stomatology EDU Journal published a study in the summer of 2018 that recommended using a spectrometer-based method to characterize the beam profile of the curing light. Their research showed that moving away from the center of the beam revealed that the irradiation decreased. The spectrometer makes it easier to evaluate the beam profile than other methods.1

Blue Light Analytics recommends moving the light around to increase the uniformity of the light’s beam profile on the surface of the materials. They also recommend increasing the curing time to ensure that the material has enough time in the hot spot as you move it to reach an adequate cure.1

Regular testing of your curing light can help you reduce the risks that your curing light poses on your ability to cure material properly. By checking the light output, the light source tip, and the beam profile you are ensuring that many of the crucial areas of your curing light are operating the way they should—or let you know that it’s time to replace it.

References
1. The Hidden Risks of a Bad Dental Curing Light [Infographic] | Bluelight. Bluelight. https://www.bluelightanalytics.com/resources/blog/hidden-risks-bad-curing-light-infographic. Accessed May 14, 2021.
2. Light Curing 101: Is Your Curing Light Putting Your Restorations at Risk?. Bluelight.wistia.com. https://bluelight.wistia.com/medias/lnzmh1ooya. Published 2021. Accessed May 14, 2021.