Use of Integrating Sphere Technology To Provide Uniform, High-intensity Light and Wavelength Mixing from Light Emitting Diodes


Current State of the Art: 

Since 2000, photoactive composites material used in fillings have become widespread in restorative dentistry.  Cosmetically appealing, these white fillings have become the standard, increasing from approximately 68 million composite fillings in 1999 to close to an estimated 100 million procedures in 2011.  Crowns remain a substantial portion of restorative dentistry with 43 million procedures estimated for 2011.


To perform these restoration procedures, dentists use various light sources.  To illuminate the patient’s oral cavity, a quartz-tungsten halogen operatory light is suspended above the dental chair.  For hardening the resins used in composite filings, the dentist uses a blue curing light, For color matching of replacement crowns to the surrounding dentition, dentists are advised to use natural ‘northern light’ to ensure a good match.


Disadvantages with the Current Art:

Using these different types of illumination, dentists face two challenges: inadvertent mixing and availability.


The halogen lights used to illuminate patients’ oral cavities produce broad-band light emissions relatively evenly across the entire visible spectrum.  Consequently, the light produced mixes the blue light used to cure composite fillings and other wavelengths.  Because resins used in composite fillings are highly sensitive to blue light, dentists must ensure that the halogen lights do not cause inadvertent premature curing.  Dentists either work quickly or have their assistant hold light filters over the work area.  Working quickly reduces work quality, and using filters prevents the assistant from helping the dentist in other ways.


During crown placements, dentists match the color of materials to the patient’s existing teeth.  Proper illumination is essential to making a correct color match. Dentists should use "northem light" when shade-matching, but this requires a northerly window and sufficient sun.  Although lights exist for such color matching, because their emission spectra do not extend into the UV range, they do not activate the natural fluorescence in teeth, crucial to perceiving teeth as white. 


Advantages of Invention:    

This invention uses an integrating sphere to mix light from single or multiple LEDs and enables dental equipment vendors to replace traditional halogen operatory lights with LED light sources with predetermined frequency profiles that allow a dentist to work in a range of custom lighting conditions.  For example, a base setting would provide conventional illumination with a wide bandwidth.  During filling, a different combination of LEDs would produce light lacking the blue wavelengths that cause premature curing, and during color selection, the dentist would select an lighting regime equivalent to ‘northern light’ and augmented with UV LEDs to reliably compare the restorative material to the patient’s dentition.


Other applications requiring light sources with customizable spectra exist in other sectors such as medicine (phototherapy) and color (testing color perception under different light conditions).


Patent Status: US Pub. No. 2008/0131836


Inventor: Frederick A. Rueggeberg, DDS., MS.


Case Number: AURI 2005-023

IP status: Patent Issued

Patent Information:
Medical Devices
For Information, Contact:
Augusta University
Frederick Rueggeberg
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