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Buyer Beware! Not all Curing Lights are Equal

This post was prepared in collaboration with BlueLight Analytics

On an experimental basis, we have asked a limited number of companies to provide us with practical “How To” answers to clinical questions. We were prompted to conduct this experiment when dental team members told us that they visit company websites and consult company representatives for practical clinical information. We look forward to receiving your feedback on this experiment. 

Light cured materials (sealants, resin composite, cements) are a prominent part of dentistry.  As such, light curing units are a “must-have” in a dental practice.

An increasing number of dentists are sourcing curing lights online where they can be bought for less than the shipping charge.  The old adage “you get what you pay for” holds true with curing lights, but is complicated by the fact that effective light curing is central to the success of the restoration and patient satisfaction. 

Current estimates suggest there are more than 150 different models of light curing units available through more than 40 manufacturers.1 As one may expect, there is a lot of variation amongst the units:

  • Price range: $9 – $4,900
  • Irradiance range: 400 – 5,000 mW/cm² (as stated by the manufacturer)
  • Incremental cure time: 1 – 60 seconds
  • Cooling: air vs. water vs. no cooling system
  • As many as 6 different curing modes

If the evidence suggests that a curing light requires replacement, what factors should dentists consider before making a purchase?

QUALITY OF THE LIGHT CURING UNIT

At the American Association for Dental Research (AADR) in March 2014, researchers from the Clinician’s Report Foundation2 presented results of an examination of 11 curing lights purchased online for less than $100 each.  Their recommendation was that dentists should exercise extreme caution when purchasing “budget” curing lights:

“The absolute lack of accountability in the manufacture and distribution of these lights, as well as their lack of electrical and safety certification, make it irresponsible and a legal liability to use them on patients.”

Similarly, in the UK, the Medicines and Healthcare Products Regulatory Agency3 warned dentists against using low quality, unapproved and counterfeit curing lights:

“These medical devices should not be used on patients – their use may result in poor quality fillings and the need for additional dental treatment.”

Most examinations of these budget curing lights highlight their unstable output as well as their poor construction and durability.  All curing lights degrade with use; however, evidence suggests that “budget” curing lights may degrade more rapidly.  Once degradation begins, the curing light ceases to deliver the performance required by the material/dentist even if the unit still emits blue light.

PERFORMANCE OF THE LIGHT OVER DISTANCE

BlueLight Analytics conducts independent detailed testing of curing light performance that has confirmed well-documented research findings4,5,6,7; the irradiance produced by many curing lights drops quickly and significantly at clinically relevant distances of 4 mm or more.

The following table lists curing lights from high quality manufacturers that deliver at least 80% of their tip irradiance when used at a distance of 4 mm (a common clinical scenario).  

Table

*Only the baseline irradiance is reported, not the pulse

PRODUCT ALIGNMENT

A quality curing light can be used effectively with a different manufacturer’s resin composite as long as the output of the curing light has been accurately tested and the cure time is adjusted according to the material manufacturer’s stated requirements for the selected brand and shade.

If a clinician is looking to purchase a new curing light, and is satisfied with their resin composite materials, they may consider using a curing light produced by the material manufacturer.  The reason for this is that it is highly likely that the curing light from the manufacturer has been verified as effective when used with their own materials.

Most importantly, when deciding on a light curing unit, clinicians should consider the cost of the light on a per use basis as well as the overall cost in delivering quality care to their patients.

Example:       

  • $1,500 curing light
  • Use light for 4 years
  • Assume ~1000 restorations/year
  • Cost of curing light ~40₵ per restoration
  • ($1,500 ÷ 4 years ÷ 1,000 restorations/year).

For additional information, see related Oasis articles:

Practical How To: How do you clean your light curing unit?

An EnLIGHTening look at light sources in dentistry

References

  1. BlueLight Analytics Inc. (Halifax, Nova Scotia) checkMARC™ database
  2. Palmer TM, et al, Performance and Features of Inexpensive LED Curing Lights. J Dent Res 2014;93A:315 (www.iadr.org)
  3. Medicines and Healthcare Products Regulatory Agency (MHRA), October 7, 2013 News Release (http://www.mhra.gov.uk/NewsCentre/Pressreleases/CON322349)
  4. Price RB, Labrie D, Whalen JM, Felix CM. Effect of distance on irradiance and beam homogeneity from 4 light-emitting diode curing units. J Can Dent Assoc 2011;77:b9.
  5. Rode KM, Kawano Y, Turbino ML. Evaluation of curing light distance on resin composite microhardness and polymerization. Oper Dent 2007;32(6):571-578.
  6. Aravamudhan K, Rakowski D, Fan PL. Variation of depth of cure and intensity with distance using LED curing lights. Dent Mater 2006;22(11):988-994.
  7. Xu X, Sandras DA, Burgess JO. Shear bond strength with increasing light-guide distance from dentin. J Esthet Restor Dent 2006;18(1):19-27.

One comment

  1. Thank you for enlightening your readers about concerns many researchers have about budget curing lights that are often purchased on the internet. I have seen an influx of these budget curing lights that are not compliant with Health Canada’s Medical Device Regulations and that have a very poor performance compared to approved lights from major manufacturers. Often the dentist is unable to measure how bad these lights really are. Yes, they do ‘get what you pay for’, but the patient is not offered the choice of receiving a restoration that has been cured by fully functional and approved device, or by something whose performance is unknown.
    For more information, see:
    1. Price R, Shortall A, Palin W. Contemporary Issues in Light Curing. Operative Dentistry 2014; 39:4-14.
    2. Strassler HE, Price RB. Understanding Light Curing, Part 1 Delivering Predictable and Successful Restorations. Dentistry Today. http://www.dentalcetoday.com/courses/164/PDF/DT_May_14_173_fnl1.pdf
    3. Strassler HE, Price RB. Understanding Light Curing, Part 2 Delivering Predictable and Successful Restorations. Dentistry Today. http://www.dentalcetoday.com/coursereview.aspx?url=165%2FPDF%2FDT_June_14_174_fnl.pdf&scid=170
    Recent presentations at Scientific Meetings:
    1. Kevin B. Frazier, Frederick A. Rueggeberg, Richard Price. Teaching The Science And Clinical Application Of Photo-Curing. ADEA 2014. Abstract 022.
    2. R.B. Price, P. Michaud, F.A. Rueggeberg, H. Price, D. Labrie, M. Alshaafi, M.Q. Alqahtani, And H. Strassler. Power And Irradiance Beam Uniformity From Budget Curing Lights.AADR;2014 Abstract #308.
    3. M.Q. Alqahtani, R.B. Price, M. Alshaafi, D. Labrie, H. Strassler, and H. Price. Irradiance And Power Output From Ten Budget Curing Lights. AADR;2014 Abstract #309.
    4. R.B. Price, F.A. Rueggeberg, D. Labrie, H. Strassler, And M. Alshaafi . Light Transmission And Beam Uniformity From Curing Lights Through Resin. IADR;2014. Abstract #135.
    5. R.B. Price. Curing Lights: They Are All The Same, Aren’t They? Keynote Address: IADR;2014. Abstract #1392.
    6. OASIS: Are you using a licensed device: http://www.oasisdiscussions.ca/2014/05/26/lmd

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