ABSTRACT
Background: Bacterial contamination on surgical masks puts a threat to medical staff and patients. The aim of the study was to investigate its contamination during dental treatments, wearing a face shield and performing a pre-procedural mouth rinsing with chlorhexidine (CHX). Methods: In this prospective, randomized study, 306 treatments were included, 141 single-tooth (restorations) and 165 total dentition treatments (preventive or periodontal supportive ultrasonic application). A total of three groups (each: n = 102) were formed: participants rinsed for 60 s with 0.1 % CHX or with water before treatment, and, for control, a non-rinsing group was included. In view of the COVID-19 pandemic, a face shield covering the surgical mask enhanced personal protective equipment. After treatment, masks were imprinted on agar plates and incubated at 35°C for 48 h. Bacteria were classified by phenotypic characteristics, biochemical assay methods, and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS). Colonies (CFU) were counted and mean values were compared (Kruskal-Wallis-, U test, p < 0.05). Results: Chlorhexidine led to a statistically significant reduction of bacterial contamination of the surgical mask (mean: 24 CFU) in comparison with water (mean: 47 CFU) and non-rinsing (mean: 80 CFU). Furthermore, rinsing with water reduced CFU significantly in comparison with the non-rinsing group. There were no significant differences between single or total dentition treatments. Streptococcus spp., Staphylococcus spp., Micrococcus spp., and Bacillus spp. dominated, representing the oral and cutaneous flora. Conclusion: A pre-procedural mouth rinse is useful to reduce the bacterial load of the surgical mask. However, contamination cannot be prevented completely, even by applying a face shield. In particular, during pandemic, it is important to consider that these additional protective measures are not able to completely avoid the transmission of pathogens bearing aerosols to the facial region. If antiseptic rinsing solutions are not available, rinsing with water is also useful.
ABSTRACT
Despite the widespread use of antiseptics such as chlorhexidine digluconate (CHX) in dental practice and oral care, the risks of potential resistance toward these antimicrobial compounds in oral bacteria have only been highlighted very recently. Since the molecular mechanisms behind antiseptic resistance or adaptation are not entirely clear and the bacterial stress response has not been investigated systematically so far, the aim of the present study was to investigate the transcriptomic stress response in Streptococcus mutans after treatment with CHX using RNA sequencing (RNA-seq). Planktonic cultures of stationary-phase S. mutans were treated with a sublethal dose of CHX (125 µg/mL) for 5 min. After treatment, RNA was extracted, and RNA-seq was performed on an Illumina NextSeq 500. Differentially expressed genes were analyzed and validated by qRT-PCR. Analysis of differential gene expression following pathway analysis revealed a considerable number of genes and pathways significantly up- or downregulated in S. mutans after sublethal treatment with CHX. In summary, the expression of 404 genes was upregulated, and that of 271 genes was downregulated after sublethal CHX treatment. Analysis of differentially expressed genes and significantly regulated pathways showed regulation of genes involved in purine nucleotide synthesis, biofilm formation, transport systems and stress responses. In conclusion, the results show a transcriptomic stress response in S. mutans upon exposure to CHX and offer insight into potential mechanisms that may result in development of resistances.
ABSTRACT
OBJECTIVE: Coronavirus disease 2019 (COVID-19) caused by infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread worldwide. Since reducing the amount of virus in saliva is considered to prevent broader infection, the Center for Disease Control (CDC) and American Dental Hygienists' Association (ADHA) have recommended use of CPC- or CHX-containing oral care products before the dental procedure. However, there is no certified evidence. So, we examined inactivation of SARS-CoV-2 by oral care products in several countries in vitro. METHODS: 0.05 % Cetylpyridinium chloride (CPC) mouthwash, 0.05 % CPC toothpaste and 0.30 % CPC spray in Japan; 0.06 % chlorhexidine gluconate (CHX) + 0.05 % CPC mouthwash and 0.12 % CHXâ¯+â¯0.05 % CPC mouthwash in Europe; 0.075 % CPC mouthwash, 0.12 % CHX mouthwash, and 0.20 % delmopinol hydrochloride mouthwash in the USA; and 0.04 % CPC mouthwash in China were assessed for their virucidal activity with ASTM E1052. RESULTS: The virus was inactivated in vitro by the contact time in directions for use of all oral care products containing CPC or delmopinol hydrochloride as anticeptics. CONCLUSIONS: These results suggest that these oral care products in each country may reduce the viral load in the mouth.