Discussing the updates on the PDA Interim Guidelines
on Infection Prevention for CoVid-19 Pandemic
(Part 8)
Last week, we mentioned the use of ultra violet germicidal irradiation (UVGI) in helping eliminate possible infections resulting from the spread of the SARS-CoV-2 virus. There are some factors influencing UVGI performance and these are the following:
1. Irradiance and dose-product of intensity and exposure duration
2. Microbial sensitivity – (lacks evidence for SARS-CoV-2)
3. Wavelength of received radiation
4. Humidity – microbes found to be resistant at higher humidities
5. Temperature – high or low temperatures may affect UVGI output of
the low pressure mercury lamps or decrease the microorganism’s
sensitivity to UVGI.
If UVGI is used properly, following the manufacturer’s instructions, they can be effective and safe in reducing airborne infection.
UVGI decontamination is potentially hazardous to humans and must be done strictly following the manufacturer’s instructions.
UVGI may be absorbed by surfaces of the eyes and skin; and short term exposure may result in photokeratitis and/or keratoconjunctivitis.
Moreover, the symptoms may manifest 6-12 hours after the exposure. The symptom may cause a mild sensation of sand in the eyes and tearing; mild to moderate, skin overexposure is similar to sunburn; severe, eye pain.
It is noteworthy to understand that there are no evidences on the use of UVGI on SARS CoV2.
The advice to dental professionals to please check devices as some contain compressed mercury.
Moving on, there are extra-oral vacuum machines (EOVM) that can be used to eliminate the risks that may come as a result of exposure to potential carriers of the coronavirus disease (Covid) virus.
Dental procedures necessitating the use of equipment and machines, driven by air turbine, will create a spray of aerosolized saliva, inadvertently spreading the virus to the dental staff in very close range and may stay suspended contaminating the air within the operatory.
The size of the aerosol determines the rate of its spread in the environment and the distance of distribution on surfaces.
A machine which can suction the aerosol may decrease microbial contamination.
However, these machines may be more sensitive to large particulates like bacteria or the smaller sized virus to about 0.5-5um only. The smallest size virus isolated for the SARS-CoV2 is 0.2um.
This may not still effectively eliminate the minute sized SARS CoV2 virus, but it may still significantly reduce the microbial count within the operatory, during an aerosol generating procedure.
The direction and distance of the suction cone increases the ability of the machine to absorb aerosols. The suggestion is that absorption ability could be dependent on the power of the machine.
When combined with other measures, such as use of rubber dam, minimal treatment time, the use of EOVM may decrease viral exposure during aerosol generating procedure (AGP), since it adds another layer of protection for the dental team.
After the procedure, some experts recommend to leave the machine open at a lower speed to further decontaminate the dental workspace.
It should be understood that this is NOT to replace a negative air pressure environment recommended when managing Covid positive patients. It should not a reason for complacency in using the device for AGP.
It is also important to know the proper management and elimination of waste products.
Dentistry has been found to be one of the professions with the highest risk of being infected with the Covid virus because dental professionals and staff work near the patient’s mouth and are constantly exposed to patients’ saliva and aerosols produced during drilling of teeth and other dental procedures. As salivary glands have been found to be potential reservoirs for Covid asymptomatic patients, everything that enters the patient’s mouth or was in contact with the patient’s saliva is considered infectious and disposed of or treated as such.
Proper waste management becomes more important in the time of the Covid pandemic as dental clinics are expected to produce higher amount of infectious and other wastes from increased used of personal protective equipment (PPE) and more stringent infection control measures.
Dental professionals should consider all infectious waste such as used gloves, single PPE must be placed in the yellow bag and covered during the workday. At the end of the day, this bag must be deposited in a suitable location outside of the clinic for waste disposal and away from the public and potential scavengers.
Dental professionals should make sure to make arrangements at the place of work and find out how or when waste can be disposed of properly.
Infectious PPE intended for reuse such as gowns, goggles, protective eyewear, face shields and respirator masks must likewise be placed in a separate bag or bin.
Reusable gowns may be disinfected by washing them separately from your personal clothing.
Disinfect the gowns by spraying or soaking them in a 0.1% chlorine bleach solution for 5 minutes and wash with detergent and water the usual way.
Polycarbon and propionate goggles, protective eyewear and face shields may be disinfected with 0.1% chlorine bleach solution, rinsed, wiped and dried.
Respirator masks may be reused only if they are not heavily or visibly soiled or were not exposed heavily to aerosols or droplets (non-AGP procedures or very short AGP procedures).
However, the process of disinfecting involves subjecting these masks to dry heat (in an oven) at 70 degrees Celsius for 30 minutes. The masks must be fit tested
Next week, we will give additional insights on the waste management for dental clinics to prevent the spread of the virus causing the SARS-CoV-2.