Curing Light

A comprehensive guide to a curing light

A curing light is a tool used for the polymerization of resin-based composites. This technique is implemented in several dental conditions that are curable by light. This light usually falls under the visible blue light spectrum. It delivers a wide range of wavelengths, varying depending on the type of device used and the light source (e.g., tungsten halogen, LED, plasma arcs, laser). In this article, we will cover the history of curing light, the physics behind this invention, and the main indications of use.

History 

In the 1960s, the first curing light was developed by Dentsply/Caulk and was given the name Nuva light. This device used ultraviolet light to cure resin composites. Still, it was shortly discontinued form the market due to this feature and the poor penetration of UV light into the deeper layers of the resin. Jumping forward to the 1980s, many scientists and researchers took an interest in this technology, which led to the development of a device that utilizes blue light. After that, the halogen bulb became available and gained popularity because it offers longer wavelengths and allows for greater tissue penetration. Shortly after this device was released, UV light-based devices disappeared from the market.

In the 1990s, more improvements were incorporated into light curing devices, which coincided with the advances made in dental restoration materials.

In 1998, plasma arc curing light got released into the market; this technology used a high-intensity source of light (fluorescent bulb containing plasma) to cure resin composites, with an estimated action time of around 3 seconds. Due to practical issues that faced these devices, plasma arc curing light did not reach the expected value, but it was crucial for developing similar products. Over the years, LED curing light became the gold standard due to the frustration associated with using plasma arc curing light, leading to the massive popularity of LED devices that we see today.

How does curing light work?

As stated earlier, blue light serves to polymerize light-cured resin-based dental materials. This technology became pivotal in the different fields of dentistry regardless of the specialty.

Blue light devices convey the luminal energy of an emission spectrum, which is then absorbed to commence polymerization chemical reactions of the composite material. This process is often referred to as photo-polymerization. To choose the right device, the dentist will consider the intensity and dental application of each case. For instance, irradiance is measured by calculating power output, or milliwatts (mW), of a curing light across the surface area of the blue light guide. It must deliver a minimum irradiance of 400mW/cm2 for a time interval to adequately polymerize a 1.5-2mm thick resin composite. Often, clinicians take into consideration the case of the patient to choose the right blue light.

Indications to use blue light devices

As stated above, blue light is used for photo-polymerization in several dental procedures that involve the filling of caries and the removal of stains. As these devices become more compatible with dental materials, their uses and indications become broader and more diverse.

The exact indications of this technology vary between dentists and clinics, depending on the school they follow and the education they receive. However, healthcare facilities organize regular events to emphasize the role of blue light in the world of dentistry and the importance of choosing the right parameters on a case-to-case basis.

Fortunately, these efforts are starting to deliver results since more patients are receiving high-quality dental care, and satisfaction levels are through the roof.

The complications of using blue light

According to studies, dental curing light carries several risks, including phototoxic and photoallergic reactions, potential oral tissue and dermal effects, and potential danger on eyesight.

You see, blue light might trigger a cascade of chemical reactions that skyrocket the concentration of reactive oxygen species (ROS) in the dental tissue and surrounding structures, leading to allergic reactions, and in some cases, anaphylactic shock.

Once again, the powerful energy released from the device might be damaging to the oral mucosa, putting the patient at risk of ulcers and cavitary infections.

The most severe adverse effect of blue light radiation is eyesight damage, which is often the result of cumulative exposure to blue light without proper protection.

This process can be explained by understanding the anatomy and physiology of the ocular system. Generally speaking, the eye receives visible light and interprets it using specialized photoreceptors in the retina. These receptors are prone to injury induced by photochemical sources, especially if the radiation's intensity is elevated.

To put things into perspective, blue light's retinal damage has similar consequences to those seen from direct exposure to ecliptic sunlight.

As cited above, the damage is cumulative, meaning that short exposure to a high radiation source yields similar results to prolonged exposure to a moderate/mild source of radiation.

Fortunately, most patients recover the full function of their eyesight, except for rare occasions that result in permanent retinal injury, presenting clinically as a blind spot in the center of the visual field.

Market-leading brands of blue light devices

The incidence and prevalence of dental pathologies that involve tooth decay and caries are continuously on the rise, which requires more dental filling procedures.

During the process of filling dental caries, LED dental blue lights must be used for the photo-polymerization. This is the critical factor that led to the high market demand for these devices.

Experts believe that the market for LED dental curing lights is expected to grow in the near future due to an upcoming set of developments and advanced features that include the use of I-40 Ultracapacitor to replace the batteries and the augmentation of 12 mm to cover more dental surfaces exponentially.

In one report, experts state that the global market is expected to grow by USD 47.48 million between 2018 and 2022. 

The top leading companies of the curing light devices market include:

  • 3M
  • DentLight
  • Dentsply Sirona
  • Ivoclar Vivadent
  • Kerr Corporation
  • VOCO

General specifications of these devices

Most blue light devices have to comply with certain requirements that include:

  • The production of light in a broad and blue-violet emission spectrum
  • The compatibility with different dental materials
  • A light intensity of 1,000 mW/cm2 or higher
  • The inclusion of a radiometer to check the light intensity
  • The statement of minimum light intensity and tolerance values
  • The availability of data about heat development during polymerization
  • The equipment of the device with a lithium battery
  • The shelf life of the battery and its operational duration
  • The availability of an induction charging technology to allow for debris cleaning
  • The availability of corded operation
  • The degree of sound produced by the device

For a device to have a chance in today's market, it must cover the vast majority of the criteria listed above.

Fortunately, the leading companies are fiercely competing to produce the highest-quality devices to serve dentists and their patients.

Takeaway message 

Curing light devices are a fantastic innovation that allowed the polymerization of resin-based composites without the need for invasive procedures and the unnecessary removal of teeth.

Hopefully, this article helped you appreciate the value of this technology and the economic aspects of its expected growth.