Risk of contamination in dental surgery

COVID-19 Pandemic and

Risk of contamination in Dental Practice

The COVID-19 pandemic has only exacerbated the pre-existing conditions by overwhelmingly highlighting the risk of contagion that dentists, collaborators and patients run due to the aerosol produced by rotating instruments during normal dental practice.

It now seems established that COVID-19 is capable of living in water.

It is therefore evident that the asymptomatic patient who undergoes dental treatment, in addition to transmitting the virus through the aerosol generated during dental practice, can in fact further contaminate the unit’s water circuit, by backflow, and consequently make all subsequent dental practices extremely risky, for doctors, assistants and above all on patients, submitting them not only to the risk of contaminated aerosol but also to the risk of contact with open wounds.

The formation of biofilm inside the hydraulic circuits of the dental units finds its origin in the double possibility of contamination :

  • upstream, from the water mains;
  • downstream, from the wastewater coming from the patient’s mouth.

Among the many infectious and pathogens agents, both viral and bacterial found in the water mains of dental clinics, some are particularly dangerous : Legionella Pneumophila, Pseudomonas, Mycobacterium Tuberculosis, AIDS and Hepatitis C virus.

The water, so contaminated and containing bacterial loads thousand times higher than limits fixed for drinking water, makes vain even the most correct sterilization practices of turbines, handpieces, scalers and instrumentation in general because, after the autoclave cycle, they are connected to a contaminated hydraulic circuit.
This fact is verifiable through a simple bacteriological water analysis.

We must also consider that, using the tools of the dental units, viruses and bacteria which are in the water circuits are atomized in the environment in the form of aerosols and come into direct contact with the patient’s wounds subjected to treatment.
The risk of cross infection between dentist, patient and assistants is therefore very high and it consequently needs to be contrasted through appropriate tried and tested systems.

The recent current interest in pathologies deriving from Legionella Pneumophila, has to make us aware to other much more worrisome pathologies, and consequently address our attention towards the adoption of systems which can avoid the formation of biofilm and effectively contrast the bacteria proliferation.


The biofilm is a complex aggregation of microrganisms of different species that interact with each other thereby developing resistance to disinfectants and biocides.
It forms rapidly inside the water pipes of the dental unit since the bacteria coming from the water mains are added to the ones coming from the patient’s mouth.
It is therefore essential to take appropriate preventive measures to reduce and, even better, prevent its formation since it represents a significant source of contamination for doctors, patients and assistants.

Cross infections:
The cross infection are transmitted between patients, between operator, patient and viceversa and between environment, patients and operators.
They make up a serious morbidity problem because any dental surgery, which is most of the time invasive, spreads in the environment, in the air and on every surface, the microrganisms of the oral cavity of patients and the ones present in the water ducts of the dental unit.
Hence, the necessity of intervention in order to limit their dispersion and to lower the threshold within the safety limits set by the World Health Organization’s parameters.

Legionella Pneumophila:
Legionella is a bacteria and there are several species of it.
Among those species, Legionella Pneumophila is the most dangerous because it is responsible for about 90% of Legionellosis cases, a lung infection that presents common symptoms to other forms of pneumonia.
Legionella bacteria can colonize the water mains of the dental units and the dental clinic in general and can be found either in free form in the water, than in the biofilm.
The Legionellosis is not transmitted from person to person: the use of turbines, handpieces and scalers, however, generates an atomization that cause the dispersion in the air of bacteria that can infect patients, doctors and assistants in the clinic.
From here derives the necessity to operate with decontamined water, free of any bacterial and viral form potentially present in it.

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