UVC light and infections
UVC would kill microorganisms remaining after root canal therapy and stimulate local cells to produce biomolecules that would reduce inflammation, relieve pain, and promote healing.
The problem-what is an endodontic infection?
An endodontic infection is a bacterial infection of the tooth’s pulp, which is the innermost tissue containing blood vessels, nerves, and connective tissue. Infection occurs when microorganisms enter the pulp through tooth decay, cracks, or trauma to the tooth. Once inside, bacteria multiply, leading to inflammation, pain, and swelling.
If untreated, the pulp may die, forming a periapical abscess at the root tip, which can destroy bone and cause persistent infection. Standard endodontic treatment, or root canal therapy, removes the infected tissue and disinfects the canal system, but complex root anatomies and biofilm-forming bacteria can leave behind residual microorganisms that may cause reinfection and treatment failure.
The solution-root canal therapy and its limitations
Root canal therapy (RCT) is an effective procedure that involves numerous steps: 1. Access the infected pulp chamber; 2. mechanically clean and shape the root canals; 3. chemically disinfect the canal system; and 4. seal and restore the tooth.
However, some bacteria persist in deep dentinal tubules and lateral canals, beyond the reach of standard irrigants or instruments. These surviving microbes including Enterococcus faecalis, a frequent cause of persistent infections, can lead to reinfection, retreatment, or tooth loss.
To further improve RCT outcomes, an adjunctive disinfection step is needed to eradicate remaining microorganisms before the canal is sealed.
The UV spectrum
The UV spectrum has three regions: UVC (200-290 nm), UVB (290-320 nm), and UVA (320-400 nm).
Antimicrobial activity spans 200-400 nm, with an optimum at 255-280 nm; tissue regeneration activity spans 200-450 nm, with an optimal range of 255-405 nm.
Our solution–UVC light for enhanced disinfection
We propose the use of Ultraviolet C (UVC) light as an adjunctive procedure to enhance root canal disinfection. UVC light at 265 nm has strong antimicrobial activity, rapidly killing endodontic microorganisms.
Using miniaturized LED technology integrated with fiberoptic tips, our handheld device (see left) can target UVC light deep within the root canal (see below), where conventional methods cannot reach.
In preclinical studies, UVC exposure for 30 seconds can kill E. faecalis within root canal models. Beyond microbial killing, UVC also stimulates human cells to produce biomolecules involved in reducing inflammation, relieving pain, and promoting tissue healing. This dual action (e.g., disinfection and biological stimulation) offers a new way to improve treatment outcomes and reduce retreatment rates in endodontic care.
Enterococcus faecalis
A transmission electron micrograph showing E. faecalis. It is a bacterium commonly isolated from patients with endodontic infections.
Hand-held device
UVC emitted from a handheld device (shown in clamp) can kill E. faecalis in 30, 60, and 90 seconds, with killing occurring as early as 2-4 seconds after exposure.
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Fiberoptic tips
A glass slide chamber containing fluorescent dye used to show UVC light emitted from the tip of a fiberoptic filament.
Proposed use
The small fiberoptic tip would be placed deep inside an instrumented root canal as shown in this tooth model of endodontic infection.
Proposed treatment
In this cutaway illustration of a root canal, UVC would kill microorganisms and stimulate local cells to produce biomolecules that reduce inflammation, relieve pain, and promote healing.
Direct microbial killing
UVC at 265 nm emitted from a hand-held device significantly (p < 0.05) kills E. faecalis in root canal models after 30 seconds of exposure.