Detection of dental fomites using topical fluorescein

Abstract

Background Thorough disinfection of dental facilities is of paramount importance during the COVID-19 pandemic. Patients, clinicians, students and nurses can all be infected by aerosols and dental droplets bearing COVID-19. However, droplets are transparent and often microscopic, so are difficult to detect in clinical practice.Methods To better understand the spread of dental droplets, we stained the dental irrigant with fluorescein and performed a series of procedures on a dental manikin. We then viewed droplets and fomite spread around the dental chair, with and without an ultraviolet (UV) light.Results Observations without the UV light showed minimal or no fluid spread. However, using UV light, we detected fluorescein on the dentist, chairs and the handpiece, as well as splatter on the floor and on the instrument tray. This was of educational value to the staff, who were reminded how far droplets had spread.Conclusion Fluorescein facilitates the detection of droplet spread and helps clinical staff to see high-risk areas that require in-depth cleaning. As clinical grade fluorescein is cheap and widely available, this technique may be useful for dental practices to train staff in the thorough decontamination of the clinical environment.

Fig. 1

Fluorescein staining of dental instruments. Note that the handle of the mirror is particularly affected

Fig. 2

Paper towels and bibs used during the dental procedure. Seeing the amount of fluorescence indicated that they could be highly infective

Fig. 3

Evidence of fomite transfer of fluorescein on the back and side of the dental chair; these fluorescein markings were in the form of a smear not droplets, indicating they had come from a contaminated hand or instrument

Fig. 4

Droplet spread on the floor - these were invisible without UV light