## 4 Discussion  
A high contamination risk amongst dentists appears to be suggested by these results, even though the treatment procedures performed as part of this study were not aerosol-generating. As an initial investigation, this study was conducted using a relatively small number of Petri dishes (56); nevertheless, its results may already suggest a number of partial conclusions which yield useful clinical implications. Naturally, further experimental studies, using larger numbers of Petri dishes and possibly other air decontamination methods, should follow, in order to elaborate a complete guide for medical offices and particularly dental offices. Other limitations of the present study, besides the number of Petri dishes, are the number of recordings, the dish placement and the investigation of only bacterial and not also viral contamination. For obvious ethical reasons, while aiming to reduce contamination risks in dental offices and thereby also limit the spread of SARS-CoV-2, the present study could not be conducted by experimentally spreading this virus in a dental office, given the immense risks such an approach would have posed to both patients and healthcare personnel. Nevertheless, strong similarities in the airborne transmission of bacteria and viruses do exist and the decontamination/disinfection methods that were employed in this study were also proven to be effective against SARS-CoV-2 [28; 30; 34]. These arguments open up the possibility of also applying the insights yielded by the current study in the prevention of SARS-CoV-2 transmission. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & **Ventilation** & \multicolumn{3}{c}{**Fogging**} & \multicolumn{3}{c}{**UVC**} & **UVC Box** \\ \hline \multirow{5}{*}{During treatment} & & **P1** & **P2** & **P1** & **P2** & **P1** & **P2** & **P2** \\ \cline{2-8}  & MHA & + & + & + & + & + & + & + \\ \cline{2-8}  & NA & + & + & + & + & + & + & \\ \cline{2-8}  & GPY & + & + & + & & & & \\ \cline{2-8}  & YPD & & + & + & & & & \\ \hline \multirow{5}{*}{After air decontamination} & MHA & + & & & & + & & \\ \cline{2-8}  & NA & & & & & & & \\ \cline{2-8}  & GPY & & & & & & & \\ \cline{2-8}  & YPD & & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Culture media that showed bacterial growth. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **MHA** & **NA** & **GPY** & **YPD** \\ \hline UVC 1.1 & 1 & 1 & - & - \\ \hline UVC 1.2 & 1 & - & - & - \\ \hline UVC 2.1 & 2 & 1 & - & - \\ \hline A 1.1 & 1 & 3 & - & - \\ \hline A 2.1 & 2 & 1 & 3 & - \\ \hline A 2.2 & 1 & - & - & - \\ \hline B2 & 2 & - & - & - \\ \hline N 1.1 & 14 & 13 & 3 & 1 \\ \hline N 2.1 & 3 & 8 & 2 & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Culture media that showed bacterial growth—number of culture-forming unites (CFU) in each Petri dish. Reducing transmission rates inside healthcare environments represents an important aim, by finding efficient methods for decontamination, thereby saving the lives of medical workers, patients and easing the pressure on the entire medical system. Other studies have also focused on SARS-CoV-2 transmission rates and on ways of decreasing the risk of its transmission [35; 36; 37]. The most relevant factors considered in further analyzing the results of our study were the efficiency of the microbial air load decrease (due to obvious medical reasons) and the time factor (mostly due to financial reasons) [38; 39]. Long pauses between patients and expensive PPE lead to a decrease in the profitability of dental practices and even to the bankruptcy of some of them. For this reason, finding a quick and economically feasible yet highly effective decontamination method is vital, especially for small, privately owned healthcare facilities. Dry fogging or nebulization has been proven to be efficient in air and surface decontamination because of its high penetrability and spread ability. It has been used in operating rooms, commercial setups, industry, etc., but it was never a common practice in dental offices.