Individual biosafety barrier in dentistry: an alternative in times of covid-19. Preliminary study

Abstract

<jats:p>ABSTRACT The return to dental practice in pandemic times is a new challenge due to the generation and dispersion of droplets and aerosols that may contain the SARS-CoV-2 virus, the etiological agent of covid-19. In the last months some droplet and aerosol containment strategies have been circulating on the internet, however, until now there is no evidence in the literature to prove the effectiveness of such barriers. Thus, using a microbial dispersion model with the fast handpiece, the aim of this preliminary study was to compare the dispersion caused by the the dental drill (DD) alone or in association with an individual biosafety barrier (IDBD / DD), which consisted of a layer of PVC film combined to a layer of polypropylene mounted on a frame. The dental drill was activated for one minute having had the water from the reservoir been replaced with a suspension of Lactobacillus casei Shirota. Petri dishes containing MRS agar were positioned at 50, 100 and 150 cm from the headboard of the dental chair at different angles (90 and 0 degrees). At 50 cm, the mean (standard deviation) of L. casei Shirota for DD was 13,554.59 (493.48) CFU, while for IDBD / DD was 570.67 (60.54) CFU (p &lt;0.0001), establishing a 96% reduction. Considering these preliminary results, the individual biosafety barrier proved effective in reducing dispersion from the dental drill in this study model, which suggests that this barrier may be a viable option to optimize biosafety in the dental environment.</jats:p>

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

“…Although the methodology used was established with only one bacterial species ( Lactobacillus casei Shirota), its main objective was to use a viable biological marker in the water reservoir of the dental chair, and consequently, provide a simulation of PCDP in dental procedures. This proposed model has already been used in a previous study and has shown no significant environmental risks [ 8 ], which is extremely important in this pandemic period. In addition, an enriched culture medium was used for the growth of Lactobacillus , thus providing more reliable results on PCDP generated during the experiments than germ-free models.…”

“…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 a previous study [ 8 ]. Thus, a viability test was performed to determine the initial concentration of 1.5x10 8 CFU / mL of L .…”

“…It has been demonstrated under experimentally induced aerosol conditions that the SARS-CoV-2 remained viable in aerosols for at least 3 h and on surfaces for up to 72 h. The longest viability was found on stainless steel (estimated mean half-life: 5.6 h) and plastic surfaces (estimated mean half-life: 6.8 h) [ 7 ]. Thus, dental associations worldwide have issued several recommendations for reopening, leading to important innovations in terms of personal protection equipment (PPE), such as individual dental biosafety barriers [ 8 ] to reduce oropharyngeal aerosol spread in closed environments [ 9 , 10 ].…”

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 .…”

“…It is of considerable interest to have methods to reduce the dispersion of splashes/droplets/aerosols during procedures. In a preliminary study, the Individual Biosafety Barrier in Dentistry (IBBD), which is a biosafety device, was tested aiming to reduce the dispersion of droplets and aerosols generated during the service, reducing the CFU count by 95% [ 11 ]. Other studies have also used bacteria colony counts [ 3 , 12 ] and other fluorescent tracers to show the distribution of the ejected material in general [ 13 , 14 ].…”