A novel dental biosafety device to control the spread of potentially contaminated dispersion particles from dental ultrasonic tips

Abstract

Strategies to return to dental practice in pandemic times is a new challenge due to the generation and spread of potentially contaminated dispersion particles (PCDP) that may contain the SARS-CoV-2, the etiological factor of the COVID-19 disease. Due to the significant dispersion of PCDP in the dental environment, the use of equipment such as ultrasonic tips have been inadvisable during the pandemic. Several clinical procedures, however, benefit from the use of such equipment. Thus, using a microbial dispersion model of PCDP, the aim of this study was to compare the dispersion caused by the dental drill (DD) an ultrasonic tip (UT) alone and the UT coupled with a Spray control (SC) device. The DD, UT (with or without the SC) were activated for one minute having had the water from the reservoir replaced with a suspension of Lactobacillus casei Shirota (1.5 x 108 CFU/mL). Petri dishes containing MRS agar were positioned at 50cm, 100cm and 150cm from the headrest of the dental chair at different angles (0 degree and 90 degrees). At 50 cm, the mean CFU (standard deviation) of L. casei Shirota was 13554.60 (4071.03) for the DD, 286.67 (73.99) for the US (97.89% reduction), and 4.5 (0.58) CFU for the UT-SC (p < 0.0001), establishing a further 98.43% reduction between UT and UT with SC. The UT with SC model proved effective in reducing dispersion from the UT, endorsing its use as an additional strategy to reduce PCDP in the dental environment in times of pandemic.

Biosafety devices to control the spread of potentially contaminated dispersion particles. New associated strategies for health environments

“…This strain was chosen because it is a bacterial species that poses no risk of environmental contamination and measures 0.5 μm (the SARS-CoV-2 virus measures 0.1 μm). Additionally, this microorganism has already been tested and validated for the dispersion model in a dental clinic environment in previous studies [ 2 , 11 ]. Thus, a viability test was performed to determine the initial concentration of 1.5x10 8 CFU / mL of L .…”

“…Petri dishes which contained less than 300 CFU of Lactobacillus casei Shirota were counted in full. Petri dishes containing myriads of CFU had colonies counted based on three areas measuring 1 cm 2 each [ 2 , 21 ]. Then, the average was calculated and multiplied by 63.62 (total area of the Petri dish).…”

“…Most dental treatments are aerosol-generating procedures (AGPs) that produce a mixture of spatter, drops and aerosols containing saliva, blood, irrigating water, and viable microorganisms (including bacteria, fungi, and viruses) [ 1 ]. Commonly used dental instruments, including dental handpieces and ultrasonic equipment, generate a large potentially contaminated dispersion particles (PCDP), which pose a risk to professionals and patients [ 2 , 3 ]. These microparticles are invisible, therefore mapping their spatial distribution within the clinical environment is neglected, consequently developing better ways to mitigate the risk of disease transmission is of great importance.…”

Untitled

“…This strain was chosen because it is a bacterial species that poses no risk of environmental contamination and measures 0.5 μm (the SARS-CoV-2 virus measures 0.1 μm). Additionally, this microorganism has already been tested and validated for the dispersion model in a dental clinic environment in previous studies [2,11]. Thus, a viability test was performed to determine the initial concentration of 1.5x10 8 CFU / mL of L. casei Shirota.…”

“…The tests were performed in triplicate. The size of the Petri dishes was 90 mm in diameter and the area 63.62 cm 2 . Petri dishes which contained less than 300 CFU of Lactobacillus casei Shirota were counted in full.…”