Bacterial contamination potential of personal protective equipment itself in dental aerosol-producing treatments

Contamination and control of environmental surfaces and personal protective equipment in dental clinics: A multi-centre study

OBJECTIVES

Dental procedures are associated with the production of aerosols, blood and saliva splashes. However, the extent of blood contamination on surfaces during dental procedures remains largely unknown. We evaluated the contamination of environmental surfaces and personal protective equipment (PPEs) in dental clinics and effects of subsequent disinfection measures.

METHODS

The study was conducted in five dental clinics in Shanghai. We quantified the contamination on environmental surfaces around dental chairs, gloves and face shields, using occult blood detection and adenosine triphosphate (ATP) bioluminescence analysis. Results of ATP tests are displayed in relative light units (RLU). Further analysis was conducted following the implementation of standardized cleaning and disinfection protocols.

RESULTS

The presence of occult blood on gloves was most frequent during tooth extraction (67.65%), while the highest RLU value were observed for crown and brace procedures (3214, IQR: 18.00-5371.00). The positive rate of occult blood on face shields was 24.00%, with a median RLU value of 59 (IQR: 14.75-206.75). Environmental surfaces most severely contaminated with occult blood were dental chair sink (87.00%), handpiece handle (48.00%), and saliva ejector handle (36.00%). Disinfection measures significantly reduced contamination levels at all sites, with both methods demonstrating substantial reductions in contamination for the dental chair sink, saliva ejector handle, and handpiece handle.

CONCLUSION

This study identified high-risk contamination sites and procedures in dental clinics. Disinfection is effective against surface contamination with blood.

Establishment of a rapid and quantitative method for detecting the range of infection exposure in preclinical dental education

BACKGROUNDS

Safe dental treatments that prevent nosocomial and cross-infections are essential for patients and dental workers. However, dental students sometimes pay inadequate attention to infection control, especially in preclinical practice, because of too much focus on technical training, such as the use of equipment, etc. The spread of infections such as SARS-CoV-2, antibiotic-resistant bacteria, and oral bacteria are sometimes lethal for medically compromised patients. Thus, the rapid and inexpensive detection system to detect and measure dental practice-related infection spread during preclinical treatment is highly desired for dental education. This study aimed to establish a method to quantify and visualize infected areas using dental phantoms for safe and effective preclinical dental practices.

METHODS

At first, we developed artificial saliva as an in vitro study, including food-derived bacteria and fluorescence dye, which is safe for application to preclinical practice education. In vitro study, the correlation between adenosine triphosphate (ATP) levels and Lactobacillus colony numbers in yogurt was examined using the ATP fluorescent method, with colony counting on yogurt only and a mixture of yogurt and ultraviolet (UV)-sensitive hand lotion. The mixed liquid of yogurt and hand lotion was used as artificial saliva. Second, we used this artificial saliva in preclinical education. The degree of contamination of personal protective equipment and dental chairs in preclinical practice using this artificial saliva was determined using the ATP fluorescent method and measuring the luminescence areas among 10 dentists, 10 dental residents, and 10 fifth-grade dental students.

RESULTS

ATP levels and Lactobacillus colony numbers in yogurt were positively correlated with yogurt alone and a mixture of yogurt and UV-sensitive hand lotions (correlation coefficient ≒ 1). Preclinical education using a mixture of artificial saliva successfully quantified and visualized infectious areas and droplets, which revealed significant differences in ATP amounts in personal protective equipment among groups according to years of experience as dental practitioners (p < 0.05).

CONCLUSIONS

An education system for infection control constructed using artificial saliva containing Lactobacillus and a UV-sensitive fluorescent hand lotion quantified the infectious areas and degrees. Thus, this method is effective in preclinical practice using dental phantoms.

Electrolyzed Saline Prevents Virus Transmission in Dental Procedures: An In Vitro Study

In dentistry, disinfection with antimicrobials is employed under different conditions and at different time points. During the COVID-19 pandemic, the use of disinfectant dental sprays was proposed, among other measures, to help prevent the transmission of infections during dental procedures that require highly effective antiseptics at particularly short contact times. The study aimed to evaluate the efficacy of electrolyzed saline (EOS) compared with other antiseptics in terms of the spread of enveloped and nonenveloped viruses by ultrasonic scaler (USS)-generated dental spray. Suspension tests were performed to evaluate the antiviral efficacy of EOS against herpes simplex virus 1 (HSV-1) and human adenovirus (HAdV), which served as models for enveloped and nonenveloped viruses, respectively. EOS, mostly composed of hypochlorous acid (HOCl), reduced the amount of both virus types in the presence or absence of artificial saliva by > 4 log10 50% tissue culture infectious dose (P < 0.001). In addition, the mechanism of virucidal effect was investigated using transmission electron microscopy. Following this assessment, a virus-laden dental spray transmission model was used to simulate virus-infected patients undergoing dental procedures with USS. Attenuation was achieved by substituting the USS coolant with one of the effective, pretested antiseptics. Due to safety concerns, nonhuman viral pathogens-equine arteritis virus (EAV) and feline calicivirus (FCV)-served as enveloped and nonenveloped virus models, respectively. Viral infection was evaluated by direct droplet/aerosol infection of RK-13 or CRFK cells. In addition, the biocompatibility of the antiseptics was tested with exposure to human oral keratinocytes. EOS demonstrated strong virucidal activity against both enveloped and nonenveloped viruses and was able to absolutely prevent airborne transmission of EAV and FCV through dental spray in the splatter and droplet/aerosol samples. The study emphasized that EOS, a chlorine-based antiseptic, is a promising, reasonably safe, broad-spectrum agent for preventing dental spray-mediated viral transmission.

Hygiene practices and antibiotic resistance among dental and medical students: a comparative study

PURPOSE

Healthcare students' hand and smartphone hygiene is critical due to potential pathogenic and antibiotic-resistant bacteria transmission. This study evaluates hygiene practices in medical and dental students at Kuwait University, exploring antibiotic resistance gene prevalence.

METHODS

Swab samples were collected from the hands and smartphones of 32 medical and 30 dental students. These samples were cultured on Columbia Blood Agar and McConkey Agar plates to quantify bacterial colony-forming units (CFUs). The extracted DNA from these colonies underwent RT-PCR to identify antibiotic resistance genes, including tem-1, shv, blaZ, and mecA. Additionally, a questionnaire addressing hygiene practices was distributed post-sample collection.

RESULTS

Medical students exhibited more frequent hand hygiene compared to dental students (P ≤ 0.0001). Although significantly fewer bacterial CFUs were found on medical students' smartphones (mean = 35 ± 53) than dental students' (mean = 89 ± 129) (P ≤ 0.05), no significant differences were observed in CFU counts on their hands (medical: mean = 17 ± 37; dental: mean = 96 ± 229). Detection of at least one of the targeted antibiotic resistance genes on medical (89% hands, 52% smartphones) and dental students' (79% hands, 63% smartphones) was not statistically significant. However, the prevalence of two genes, tem-1 and shv, was significantly higher on medical students' hands (78% and 65%, respectively) than on dental students' hands (32% and 28%, respectively).

CONCLUSION

Clinically significant prevalence of antibiotic resistance genes were found on medical and dental students' hands and smartphones, emphasizing the importance of ongoing education regarding hand hygiene and smartphone disinfection. This continuous reinforcement in the curriculum is crucial to minimizing the risk of cross-contamination.

Detection of viable oral bacteria of the patient on the surgical mask of dentists

INTRODUCTION AND AIM

Bioaerosols contaminate the personal protective equipment (PPE), especially masks. The PPE harbors microorganisms from various sources. However, no previous studies have investigated the specific sources of bacteria found on used masks and their correlation with those from the treated patient.

SETTING, DESIGN, MATERIAL AND METHODS

Intraoral samples from the patient were collected prior to dental aerosol-producing treatments using a nylon flock fiber swab. After treatment, the practitioner's mask was imprinted onto agar plates.

MAIN OUTCOME METHODS

Following cultivation, colony forming units were counted and identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). After the samples were analyzed, the intraoral samples as well as the mask samples were assessed for the presence of identical species, which were subsequently quantified.

RESULTS

126 treatments were included. One species match occurred most frequently (26.2%), followed by two (11.9%%) and three or more (3.97%). In the intraoral samples, Neisseria subflava occurred most often, within mask samples Staphylococcus epidermidis were detected most. Staphylococcus aureus could be cultivated three times more often in intraoral samples than on the mask.

DISCUSSION AND CONCLUSION

Oral microorganisms originating from the patient's oral cavity can be found on the outside of masks. When using PPE during treatments, it should therefore always be in mind that potentially pathogenic microorganisms may land on the mask becoming a source of for itself.