Measurement of airborne bacteria and endotoxin generated during dental cleaning

Visualization of airborne droplets generated with dental handpieces and verification of the efficacy of high-volume evacuators: an in vitro study

BACKGROUND

The COVID-19 pandemic led to concerns about the potential airborne transmission of the virus during dental procedures, but evidence of actual transmission in clinical settings was lacking. This study aimed to observe the behavior of dental sprays generated from dental rotary handpieces and to evaluate the effectiveness of high-volume evacuators (HVEs) using laser light sheets and water-sensitive papers.

METHODS

A dental manikin and jaw model were mounted in a dental treatment unit. Mock cutting procedures were performed on an artificial tooth on the maxillary left central incisor using an air turbine, a contra-angle electric micromotor (EM), and a 1:5 speed-up contra-angle EM (×5EM). Intraoral vacuum and extraoral vacuum (EOV) were used to verify the effectiveness of the HVEs. The dynamics and dispersal range of the dental sprays were visualized using a laser light sheet. In addition, environmental surface pollution was monitored three-dimensionally using water-sensitive papers.

RESULTS

Although the HVEs were effective in both the tests, the use of EOV alone increased vertical dispersal and pollution.

CONCLUSIONS

The use of various types of HVEs to reduce the exposure of operators and assistants to dental sprays when using dental rotary cutting instruments is beneficial. The study findings will be helpful in the event of a future pandemic caused by an emerging or re-emerging infectious disease.

Tracing ΦX174 bacteriophage spreading during aerosol-generating procedures in a dental clinic

OBJECTIVE

The aim of this study was to test the plausibility of using the ΦX174 bacteriophage as a tracer of viral aerosols spreading in a dental aerosol-generating procedure (AGP) model.

METHODS

ΦX174 bacteriophage (~ 10⁸ plaque-forming units (PFU)/mL) was added into instrument irrigation reservoirs and aerosolized during class-IV cavity preparations followed by composite fillings on natural upper-anterior teeth (n = 3) in a phantom head. Droplets/aerosols were sampled through a passive approach that consisted of Escherichia coli strain C600 cultures immersed in a LB top agar layer in Petri dishes (PDs) in a double-layer technique. In addition, an active approach consisted of E coli C600 on PDs sets mounted in a six-stage cascade Andersen impactor (AI) (simulating human inhalation). The AI was located at 30 cm from the mannequin during AGP and afterwards at 1.5 m. After collection PDs were incubated overnight (18 h at 37 °C) and bacterial lysis was quantified.

RESULTS

The passive approach disclosed PFUs mainly concentrated over the dental practitioner, on the mannequin's chest and shoulder and up to 90 cm apart, facing the opposite side of the AGP's source (around the spittoon). The maximum aerosol spreading distance was 1.5 m in front of the mannequin's mouth. The active approach disclosed collection of PFUs corresponding to stages (and aerodynamic diameters) 5 (1.1-2.1 µm) and 6 (0.65-1.1 µm), mimicking access to the lower respiratory airways.

CONCLUSION

The ΦX174 bacteriophage can be used as a traceable viral surrogate in simulated studies contributing to understand dental bioaerosol's behavior, its spreading, and its potential threat for upper and lower respiratory tract.

CLINICAL RELEVANCE

The probability to find infectious virus during AGPs is high. This suggests the need to continue characterizing the spreading viral agents in different clinical settings through combination of passive and active approaches. In addition, subsequent identification and implementation of virus-related mitigation strategies is relevant to avoid occupational virus infections.

Estimating the restraint of SARS-CoV-2 spread using a conventional medical air-cleaning device: Based on an experiment in a typical dental clinical setting

OBJECTIVES

Droplets or aerosols loaded with SARS-CoV-2 can be released during breathing, coughing, or sneezing from COVID-19-infected persons. To investigate whether the most commonly applied air-cleaning device in dental clinics, the oral spray suction machine (OSSM), can provide protection to healthcare providers working in clinics against exposure to bioaerosols during dental treatment.

METHOD

In this study, we measured and characterized the temporal and spatial variations in bioaerosol concentration and deposition with and without the use of the OSSM using an experimental design in a dental clinic setting. Serratia marcescens (a bacterium) and ΦX174 phage (a virus) were used as tracers. The air sampling points were sampled using an Anderson six-stage sampler, and the surface-deposition sampling points were sampled using the natural sedimentation method. The Computational Fluid Dynamics method was adopted to simulate and visualize the effect of the OSSM on the concentration spatial distribution.

RESULTS

During dental treatment, the peak exposure concentration increased by up to 2-3 orders of magnitude (PFU/m³) for healthcare workers. Meanwhile, OSSM could lower the mean bioaerosol exposure concentration from 58.84 PFU/m³ to 4.10 PFU/m³ for a healthcare worker, thereby inhibiting droplet and airborne transmission. In terms of deposition, OSSM significantly reduced the bioaerosol surface concentration from 28.1 PFU/m³ to 2.5 PFU/m³ for a surface, effectively preventing fomite transmission.

CONCLUSION

The use of OSSM showed the potential to restraint the spread of bioaerosols in clinical settings. Our study demonstrates that OSSM use in dental clinics can reduce the exposure concentrations of bioaerosols for healthcare workers during dental treatment and is beneficial for minimizing the risk of infectious diseases such as COVID-19.

Evaluation of Undergraduate Learning Experiences in Pediatric Dentistry during the COVID-19 Pandemic

The aim of the study was to analyze students' opinions on the learning outcomes they achieved during clinical classes in pediatric dentistry. The classes were run in various periods: before the SARS-CoV-2 coronavirus pandemic (onsite classes), in the first months of the pandemic (online classes), and in the following months of the pandemic (onsite classes with additional infection control and administrative changes in patients' admission procedures).

MATERIAL AND METHODS

The research was conducted among fifth-year dentistry students at Poznan University of Medical Sciences. Students who completed the entire course and passed the diploma exam in pediatric dentistry were asked to complete the anonymous questionnaire providing their opinion.

RESULTS

The research results showed that, in the students' opinion, clinical classes-regardless of their form-allowed them to achieve the knowledge necessary to perform pediatric dental procedures. However, the students appreciated onsite classes significantly more compared to information and communication technologies (ICT) classes in gaining practical skills and social competence.

CONCLUSIONS

(1) The significant limitations introduced because of the SARS-CoV-2 pandemic impacted the development and implementation of modern online teaching techniques, which may very well be applied to convey theoretical knowledge after the pandemic has ended. (2) Skills and social competence, indispensable in the future dental practice of dental students, can only be obtained during onsite classes. (3) Medical universities should design standards of teaching to enable them to address a possible epidemiological threat in the future, which will enable rapid response and safe continuation of practical dental education during a pandemic.

Comparison of aerosol mitigation strategies and aerosol persistence in dental environments

OBJECTIVE

To determine the impact of various aerosol mitigation interventions and to establish duration of aerosol persistence in a variety of dental clinic configurations.

METHODS

We performed aerosol measurement studies in endodontic, orthodontic, periodontic, pediatric, and general dentistry clinics. We used an optical aerosol spectrometer and wearable particulate matter sensors to measure real-time aerosol concentration from the vantage point of the dentist during routine care in a variety of clinic configurations (eg, open bay, single room, partitioned operatories). We compared the impact of aerosol mitigation strategies (eg, ventilation and high-volume evacuation (HVE), and prevalence of particulate matter) in the dental clinic environment before, during, and after high-speed drilling, slow-speed drilling, and ultrasonic scaling procedures.

RESULTS

Conical and ISOVAC HVE were superior to standard-tip evacuation for aerosol-generating procedures. When aerosols were detected in the environment, they were rapidly dispersed within minutes of completing the aerosol-generating procedure. Few aerosols were detected in dental clinics, regardless of configuration, when conical and ISOVAC HVE were used.

CONCLUSIONS

Dentists should consider using conical or ISOVAC HVE rather than standard-tip evacuators to reduce aerosols generated during routine clinical practice. Furthermore, when such effective aerosol mitigation strategies are employed, dentists need not leave dental chairs fallow between patients because aerosols are rapidly dispersed.

Can aerosols-generating dental, oral and maxillofacial, and orthopedic surgical procedures lead to disease transmission? An implication on the current COVID-19 pandemic

Various dental, maxillofacial, and orthopedic surgical procedures (DMOSP) have been known to produce bioaerosols, that can lead to the transmission of various infectious diseases. Hence, a systematic review (SR) aimed at generating evidence of aerosols generating DMOSP that can result in the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), further investigating their infectivity and assessing the role of enhanced personal protective equipment (PPE) an essential to preventing the spreading of SARS-CoV-2 during aerosol-generating procedures (AGPs). This SR was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement (PRISMA) guidelines based on a well-designed Population, Intervention, Comparison, Outcomes and Study (PICOS) framework, and various databases were searched to retrieve the studies which assessed potential aerosolization during DMOSP. This SR included 80 studies (59 dental and 21 orthopedic) with 7 SR, 47 humans, 5 cadaveric, 16 experimental, and 5 animal studies that confirmed the generation of small-sized < 5 μm particles in DMOSP. One study confirmed that HIV could be transmitted by aerosolized blood generated by an electric saw and bur. There is sufficient evidence that DMOSP generates an ample amount of bioaerosols, but the infectivity of these bioaerosols to transmit diseases like SARS-CoV-2 generates very weak evidence but still, this should be considered. Confirmation through isolation and culture of viable virus in the clinical environment should be pursued. An evidence provided by the current review was gathered by extrapolation from available experimental and empirical evidence not based on SARS-CoV-2. The results of the present review, therefore, should be interpreted with great caution.

Air Quality in a Dental Skills Lab during the SARS-CoV-2 Pandemic: Results of an Experimental Study

Objectives

The study aimed to analyze different ways to control air quality during/after aerosol-generating procedures (AGPs) in a small skills lab with restricted natural air ventilation in preclinical dental training (worst-case scenario for aerogen infection control). Different phases were investigated (AGP1: intraoral high-volume evacuation (HVE); AGP2: HVE plus an extraoral mobile scavenger (EOS)) and afterward (non-AGP1: air conditioning system (AC), non-AGP2: AC plus opened door).

Methods

Continuous data collection was performed for PM1, PM2.5, and PM10 (µg/m³), CO2 concentration (ppm), temperature (K), and humidity (h⁻¹) during two summer days (AGP: n = 30; non-AGP: n = 30). While simulating our teaching routine, no base level for air parameters was defined. Therefore, the change in each parameter (Δ = [post]-[pre] per hour) was calculated.

Results

We found significant differences in ΔPM2.5 and ΔPM1 values (median (25/75th percentiles)) comparing AGP2 versus AGP1 (ΔPM2.5: 1.6(0/4.9)/−3.5(−10.0/−1.1), p=0.003; ΔPM1: 1.6(0.6/2.2)/−2.2(−9.3/−0.5), p=0.001). Between both non-AGPs, there were no significant differences in all the parameters that were measured. ΔCO₂ increased in all AGP phases (AGP1/AGP2: 979.0(625.7/1126.9)/549.9(4.0/788.8)), while during non-AGP phases, values decreased (non-AGP1/non-AGP2: −447.3(−1122.3/641.2)/−896.6(−1307.3/−510.8)). ∆Temperature findings were similar (AGP1/AGP2: 12.5(7.8/17.0)/9.3(1.8/15.3) versus non-AGP1/non-AGP2: −13.1(−18.7/0)/−14.7(−16.8/−6.8); p ≤ 0.003)), while for ∆humidity, no significant difference (p > 0.05) was found.

Conclusions

Within the limitations of the study, the combination of HVE and EOS was similarly effective in controlling aerosol emissions of particles between one and ten micrometers in skill labs during AGPs versus that during non-AGPs. After AGPs, air exchange with the AC should be complemented by open doors for better air quality if natural ventilation through open windows is restricted.

Influence of flow rate and different size of suction cannulas on splatter contamination in dentistry: results of an exploratory study with a high-volume evacuation system

Objectives

SOPs recommend high-volume evacuation (HVE) for aerosol-generating procedures (AGPs) in dentistry. Therefore, in the exploratory study, the area of splatter contamination (SCON in %) generated by high-speed tooth preparation (HSP) and air-polishing (APD) was measured when different suction cannulas of 6 mm diameter (saliva ejector (SAE)), 11 mm (HC11), or 16 mm (HC16) were utilized versus no-suction (NS).

Materials and methods

Eighty tests were performed in a closed darkened room to measure SCON (1m circular around the manikin head (3.14 m²) via plan metrically assessment through fluorescence technique. HSP (handpiece, turbine (Kavo, Germany)) or APD (LM-ProPower^TM (Finland), Airflow®-Prophylaxis-Master (Switzerland)) for 6 min plus 5 s post-treatment were performed either without suction or with low-flow (150 l/min for SAE) or high-flow rate (250 l/min/350 l/min for HC11/HC16) suction. All tests were two-tailed (p≤0.05, Bonferroni corrected for multi-testing).

Results

Irrespective the AGP, SCON was higher for NS (median [25th; 75th percentiles]: 3.4% [2.6; 5.4]) versus high-flow suction (1.9% [1.5; 2.5]) (p=0.002). Low-flow suction (3.5% [2.6; 4.3]) versus NS resulted in slightly lower but not statistically significantly lower SCON (p=1.000) and was less effective than high-flow suction (p=0.003). Lowest contamination values were found with HC16 (1.9% [1.5; 2.5]; p≤0.002), whereat no significant differences were found for HC11 (2.4% [1.7; 3.1]) compared to SAE (p=0.385) or NS (p=0.316).

Conclusions

Within study’s limitations, the lowest splatter contamination values resulted when HC16 were utilized by a high-flow rate of ≥250 l/min.

Clinical relevance

It is strongly recommended to utilize an HVE with suction cannulas of 16mm diameter for a high-flow rate during all AGPs and afterwards also to disinfect all surface of patients or operators contacted.

Particle Size, Mass Concentration, and Microbiota in Dental Aerosols

Many dental procedures are considered aerosol-generating procedures that may put the dental operator and patients at risk for cross-infection due to contamination from nasal secretions and saliva. This aerosol, depending on the size of the particles, may stay suspended in the air for hours. The primary objective of the study was to characterize the size and concentrations of particles emitted from 7 different dental procedures, as well as estimate the contribution of the nasal and salivary fluids of the patient to the microbiota in the emitted bioaerosol. This cross-sectional study was conducted in an open-concept dental clinic with multiple operators at the same time. Particle size characterization and mass and particle concentrations were done by using 2 direct reading instruments: Dust-Trak DRX (Model 8534) and optical particle sizer (Model 3330). Active bioaerosol sampling was done before and during procedures. Bayesian modeling (SourceTracker2) of long-reads of the 16S ribosomal DNA was used to estimate the contribution of the patients’ nasal and salivary fluids to the bioaerosol. Aerosols in most dental procedures were sub-PM₁ dominant. Orthodontic debonding and denture adjustment consistently demonstrated more particles in the PM₁, PM_2.5, PM₄, and PM₁₀ ranges. The microbiota in bioaerosol samples were significantly different from saliva and nasal samples in both membership and abundance (P < 0.05) but not different from preoperative ambient air samples. A median of 80.15% of operator exposure was attributable to sources other than the patients’ salivary or nasal fluids. Median operator’s exposure from patients’ fluids ranged from 1.45% to 2.75%. Corridor microbiota showed more patients’ nasal bioaerosols than oral bioaerosols. High-volume saliva ejector and saliva ejector were effective in reducing bioaerosol escape. Patient nasal and salivary fluids are minor contributors to the operator’s bioaerosol exposure, which has important implications for COVID-19. Control of bioaerosolization of nasal fluids warrants further investigation.

Dental Mitigation Strategies to Reduce Aerosolization of SARS-CoV-2

Limiting infection transmission is central to the safety of all in dentistry, particularly during the current severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Aerosol-generating procedures (AGPs) are crucial to the practice of dentistry; it is imperative to understand the inherent risks of viral dispersion associated with AGPs and the efficacy of available mitigation strategies. In a dental surgery setting, crown preparation and root canal access procedures were performed with an air turbine or high-speed contra-angle handpiece (HSCAH), with mitigation via rubber dam or high-volume aspiration and a no-mitigation control. A phantom head was used with a 1.5-mL min-1 flow of artificial saliva infected with Φ6-bacteriophage (a surrogate virus for SARS-CoV-2) at ~108 plaque-forming units mL-1, reflecting the upper limits of reported salivary SARS-CoV-2 levels. Bioaerosol dispersal was measured using agar settle plates lawned with the Φ6-bacteriophage host, Pseudomonas syringae. Viral air concentrations were assessed using MicroBio MB2 air sampling and particle quantities using Kanomax 3889 GEOα counters. Compared to an air turbine, the HSCAH reduced settled bioaerosols by 99.72%, 100.00%, and 100.00% for no mitigation, aspiration, and rubber dam, respectively. Bacteriophage concentrations in the air were reduced by 99.98%, 100.00%, and 100.00% with the same mitigations. Use of the HSCAH with high-volume aspiration resulted in no detectable bacteriophage, both on nonsplatter settle plates and in air samples taken 6 to 10 min postprocedure. To our knowledge, this study is the first to report the aerosolization in a dental clinic of active virus as a marker for risk determination. While this model represents a worst-case scenario for possible SARS-CoV-2 dispersal, these data showed that the use of HSCAHs can vastly reduce the risk of viral aerosolization and therefore remove the need for clinic fallow time. Furthermore, our findings indicate that the use of particle analysis alone cannot provide sufficient insight to understand bioaerosol infection risk.

Dentistry pathways of coronaviruses transmission: a review

The nCoV-19 in a short period of time, in lower than two months has been spread as a pandemic in all over the world. This novel type of Coronavirus which shows itself with coughing, sneezing, fatigue and respiratory symptoms which is similar to cold illness has killed more than 100,000 people. However, many protocols have been established to minimize the number of infected people, but without any border and regardless the nationality, this virus has been spread in all countries. In this review, with broad mechanistic and interdisciplinary consideration the dentistry pathways of transmission, physiology, effective and available drugs and their biological inhibiting pathways have been discussed. Among many reasons that have caused higher rate of spreading, the dental services and surgeries involve to professional-patient close contacts could be seen as one of the probable pathways of transmission for this virus. According to the more recently reported literatures, the blueprint of many individual and instrumental reasons in dentistry, could be observed in nCoV-19 infection and spreading which raise the concern of the professionals about the efficiency of conventional antiviral methods. So, results of many studies attributed to the facts that the superhydrophobic antiviral materials and surfaces are potential candidates for designing dentistry instruments with more antiviral properties.

Aerosol generated by dental procedures: A scoping review

BACKGROUND

The current pandemic has raised awareness of aerosol dispersion in dental offices. This scoping review was conducted to assess the amount and spread of aerosol generated by dental procedures.

METHODS

This scoping review followed the PRISMA-ScR protocol and was conducted by searching multiple databases adopting a core search structure for each database. Detailed eligibility criteria were applied. The authors placed no restrictions on study design, year of publication, and study location. The literature search was updated on September 15, 2021.

RESULTS

A total of 51 papers were included in this scoping review. The risk of bias assessment was not conducted as per guidelines. The majority of studies found microorganisms, bloodstains, splatters of aerosol, and particles in the air part of the search strategy. Publication dates ranged from 1969 to 2021. Data came from different dental settings locations. Several factors were identified that have an effect on the amount and spread of the aerosol and spatter.

CONCLUSION

Although it is clear that the microbial contamination occurred mainly during aerosol-generating dental procedures, our understanding of the contamination level, spread, and half-life are limited.

Characterization and mitigation of aerosols and spatters from ultrasonic scalers

BACKGROUND

Dental procedures often produce aerosols and spatter, which have the potential to transmit pathogens such as severe acute respiratory syndrome coronavirus 2. The existing literature is limited.

METHODS

Aerosols and spatter were generated from an ultrasonic scaling procedure on a dental manikin and characterized via 2 optical imaging methods: digital inline holography and laser sheet imaging. Capture efficiencies of various aerosol mitigation devices were evaluated and compared.

RESULTS

The ultrasonic scaling procedure generated a wide size range of aerosols (up to a few hundred μm) and occasional large spatter, which emit at low velocity (mostly < 3 m/s). Use of a saliva ejector and high-volume evacuator (HVE) resulted in overall reductions of 63% and 88%, respectively, whereas an extraoral local extractor (ELE) resulted in a reduction of 96% at the nominal design flow setting.

CONCLUSIONS

The study results showed that the use of ELE or HVE significantly reduced aerosol and spatter emission. The use of HVE generally requires an additional person to assist a dental hygienist, whereas an ELE can be operated hands free when a dental hygienist is performing ultrasonic scaling and other operations.

PRACTICAL IMPLICATIONS

An ELE aids in the reduction of aerosols and spatters during ultrasonic scaling procedures, potentially reducing transmission of oral or respiratory pathogens like severe acute respiratory syndrome coronavirus 2. Position and airflow of the device are important to effective aerosol mitigation.

Knowledge and Apprehension of Dental Health Professionals Pertaining to COVID in Southern India: A Questionnaire Study

Aim:

This study was intended to evaluate the knowledge and apprehension of dental health professionals pertaining to COVID-19.

Materials and Methods:

In this cross-sectional survey, a self-administered questionnaire survey was used to validate the dental health professional's knowledge and apprehension pertaining to COVID-19. In this regard, a preliminary study with a convenience sample of 124 dentists working in various clinics in southern India was conducted so as to evaluate the knowledge and apprehension of dentists related to COVID-19 in India. This study, while limited in sample size, benefits the general practitioners as target readers to assess the awareness pertaining to COVID-19.

Results:

The results of this study reveal that there exists a good knowledge among dental health professionals pertaining to the COVID-19 virus and its oral manifestations in addition to the precautions to be taken for the prevention of COVID-19 in a clinical setup. However, there exists an apprehension as well as lack of awareness pertaining to the laboratory test to be carried out in a patient suspected with COVID-19 infections as well as the role of a mouthwash and the management of contaminated air in the dental clinic.

Conclusion:

The results elicited that there is a dearth of knowledge and relatively a fair apprehension among dental health professionals pertaining to COVID-19.

Airborne particles and microorganisms in a dental clinic: Variability of indoor concentrations, impact of dental procedures, and personal exposure during everyday practice

This study presents for the first time comprehensive measurements of the particle number size distribution (10 nm to 10 μm) together with next-generation sequencing analysis of airborne bacteria inside a dental clinic. A substantial enrichment of the indoor environment with new particles in all size classes was identified by both activities to background and indoor/outdoor (I/O) ratios. Grinding and drilling were the principal dental activities to produce new particles in the air, closely followed by polishing. Illumina MiSeq sequencing of 16S rRNA of bioaerosol collected indoors revealed the presence of 86 bacterial genera, 26 of them previously characterized as potential human pathogens. Bacterial species richness and concentration determined both by qPCR, and culture-dependent analysis were significantly higher in the treatment room. Bacterial load of the treatment room impacted in the nearby waiting room where no dental procedures took place. I/O ratio of bacterial concentration in the treatment room followed the fluctuation of I/O ratio of airborne particles in the biology-relevant size classes of 1-2.5, 2.5-5, and 5-10 μm. Exposure analysis revealed increased inhaled number of particles and microorganisms during dental procedures. These findings provide a detailed insight on airborne particles of both biotic and abiotic origin in a dental clinic.

Dental education in the time of SARS-CoV-2

INTRODUCTION

The SARS-CoV-2 virus has forced profound change on all aspects of society, with significant impact on dental education. Dental students like all other dental clinical personnel are considered to be at the highest risk amongst healthcare workers due to the nature of treatment, namely, working in the oral cavity (known reservoir for the virus) and the routine use of aerosol-generating procedures. The nature of this pandemic has created several challenges to dental clinical education. The aim of this paper is to discuss these challenges and how educators have sought to overcome them.

MATERIALS AND METHODS

This paper reviews the evidence base around bio-aerosol and infection control measures specifically in the context of dental education.

RESULTS

Using current knowledge of bio-aerosol and increasing understanding of the virus, dental educators can implement evidence-based measures to ensure safe teaching within both simulation and clinical environments.

DISCUSSION

This paper contextualises the current pandemic in a dental education setting by providing a critical appraisal of the challenges posed by SARS-CoV-2 and how these challenges may be managed.

CONCLUSION

The SARS-CoV-2 pandemic has created unique challenges for dental schools worldwide. Dental educators have sought to identify these challenges and find solutions appropriate to the stage of the pandemic specific to their geographical location.

Assessment of hygienic conditions of recreational facility restrooms: an integrated approach

Introduction

Microbiological quality of recreational environments included restrooms, is generally assessed by water and surface monitoring. In this study, an environmental monitoring, conducted in spring, of swimming pool restrooms of a recreation center located in the Marche region has been carried out. Seven water samples and seven surface swabs were collected. Moreover, six air samples have been included. The aim of this study was to evaluate if air microbiological monitoring, along with molecular detection in real-time PCR, could give additional useful information about the hygienic conditions of the facility.

Methods

Heterotrophic Plate Count (HPC) both at 22°C (psychrophilic) and 37°C (mesophilic) was determined by separate cultures in all samples. The presence of Legionella pneumophila and Pseudomonas aeruginosa was evaluated by both culture and real-time PCR.

Results

The analysis of shower water recorded a HPC load of mesophilic bacteria (37°C) more than 10-fold higher in men restroom, respect to women’s one (> 100 vs < 10 CFU/ml), while in air samples was between < 100 and > 500. Concerning pathogen presence, both species Legionella pneumophila and Pseudomonas aeruginosa were detected only in men restroom, but in different sample types by using different methods (culture and real-time PCR).

Conclusions

Air sampling may offer the advantage of giving more representative data about microbial presence in restrooms, including bacterial species transmitted through aerosol, like Legionella. Moreover, the concurrent use of molecular and microbiological detection in an integrated approach could offer the advantage of greater sensitivity.

Experimental Evaluation of Aerosol Production after Dental Ultrasonic Instrumentation: An Analysis on Fine Particulate Matter Perturbation

Aerosol production represents a major concern during the majority of dental procedures. The aim of the present study is to investigate the dynamics of aerosol particles after 15 min of continuous supragingival ultrasonic instrumentation with no attempt of containment through particle count analysis. Eight volunteers were treated with supragingival ultrasonic instrumentation of the anterior buccal region. A gravimetric impactor was positioned 1 m away and at the same height of the head of the patient. Particles of different sizes (0.3–10 µm) were measured at the beginning of instrumentation, at the end of instrumentation (EI), and then every 15 min up to 105 min. The 0.3-µm particles showed non-significant increases at 15/30 min. The 0.5–1-µm particles increased at EI (p < 0.05), and 0.5 µm remained high for another 15 min. Overall, all submicron aerosol particles showed a slow decrease to normal values. Particles measuring 3–5 µm showed non-significant increases at EI. Particles measuring 10 µm did not show any increases but a continuous reduction (p < 0.001 versus 0.3 µm, p < 0.01 versus 0.5 µm, and p < 0.05 versus 1–3 µm). Aerosol particles behaved differently according to their dimensions. Submicron aerosols peaked after instrumentation and slowly decreased after the end of instrumentation, whilst larger particles did not show any significant increases. This experimental study produces a benchmark for the measurement of aerosol particles during dental procedures and raises some relevant concerns about indoor air quality after instrumentation.

Mechanisms of Atomization from Rotary Dental Instruments and Its Mitigation

Since the onset of coronavirus disease 2019, the potential risk of dental procedural generated spray emissions (including aerosols and splatters), for severe acute respiratory syndrome coronavirus 2 transmission, has challenged care providers and policy makers alike. New studies have described the production and dissemination of sprays during simulated dental procedures, but findings lack generalizability beyond their measurements setting. This study aims to describe the fundamental mechanisms associated with spray production from rotary dental instrumentation with particular focus on what are currently considered high-risk components-namely, the production of small droplets that may remain suspended in the room environment for extended periods and the dispersal of high-velocity droplets resulting in formites at distant surfaces. Procedural sprays were parametrically studied with variables including rotation speed, burr-to-tooth contact, and coolant premisting modified and visualized using high-speed imaging and broadband or monochromatic laser light-sheet illumination. Droplet velocities were estimated and probability density maps for all laser illuminated sprays generated. The impact of varying the coolant parameters on heating during instrumentation was considered. Complex structured sprays were produced by water-cooled rotary instruments, which, in the worst case of an air turbine, included droplet projection speeds in excess of 12 m/s and the formation of millions of small droplets that may remain suspended. Elimination of premisting (mixing of coolant water and air prior to burr contact) resulted in a significant reduction in small droplets, but radial atomization may still occur and is modified by burr-to-tooth contact. Spatial probability distribution mapping identified a threshold for rotation speeds for radial atomization between 80,000 and 100,000 rpm. In this operatory mode, cutting efficiency is reduced but sufficient coolant effectiveness appears to be maintained. Multiple mechanisms for atomization of fluids from rotatory instrumentation exist, but parameters can be controlled to modify key spray characteristics during the current crisis.

The COVID-19 pandemic and orthodontic practice in Nigeria

OBJECTIVES

This study was aimed at assessing the knowledge and awareness of orthodontists and orthodontic residents in Nigeria about the COVID-19 pandemic and the appropriate infection control measures required to mitigate its spread in orthodontic practice.

MATERIALS AND METHODS

It was a cross-sectional descriptive study of orthodontists and orthodontic residents. Ethical approval for the study was obtained from the Institutional Review Board. Data collection was via an online questionnaire designed using Google forms and these were sent to the phone numbers of study participants. Data analysis was done using Statistical Package for Social Sciences version 20.

RESULTS

A total of 73 respondents with a mean age of 43.41 ± 9.21 years participated in the study. About 90% of the respondents had a very good knowledge of COVID-19, including its etiology, modes of transmission, signs, and symptoms. However, very few respondents were aware of the less common symptoms such as skin rash (16.4%) and red eyes (26%). Over 80% of the respondents knew the appropriate measures to take to prevent the spread of the virus in the dental clinic, in addition to the appropriate personal protective equipment (PPE) to use.

CONCLUSION

The respondents had a very good knowledge of the basic epidemiology of COVID-19 and the means of prevention of its transmission in the dental clinic. However, there was limited knowledge of the less common symptoms of the infection. In addition, majority of the respondents had a very good idea of the appropriate PPE to be used.

Evaluating splatter and settled aerosol during orthodontic debonding: implications for the COVID-19 pandemic

Introduction Dental procedures produce splatter and aerosol which have potential to spread pathogens such as SARS-CoV-2. Mixed evidence exists on the aerosol-generating potential of orthodontic procedures. The aim of this study was to evaluate splatter and/or settled aerosol contamination during orthodontic debonding.Material and methods Fluorescein dye was introduced into the oral cavity of a mannequin. Orthodontic debonding was undertaken with surrounding samples collected. Composite bonding cement was removed using a speed-increasing handpiece with dental suction. A positive control condition included a water-cooled, high-speed air-turbine crown preparation. Samples were analysed using digital image analysis and spectrofluorometric analysis.Results Contamination across the eight-metre experimental rig was 3% of the positive control on spectrofluorometric analysis and 0% on image analysis. Contamination of the operator, assistant and mannequin was 8%, 25% and 28% of the positive control, respectively.Discussion Splatter and settled aerosol from orthodontic debonding is distributed mainly within the immediate locality of the mannequin. Widespread contamination was not observed.Conclusions Orthodontic debonding is unlikely to produce widespread contamination via splatter and settled aerosol, but localised contamination is likely. This highlights the importance of personal protective equipment for the operator, assistant and patient. Further work is required to examine suspended aerosol.

Evaluating contaminated dental aerosol and splatter in an open plan clinic environment: Implications for the COVID-19 pandemic

Objectives

Identify splatter/aerosol distribution from dental procedures in an open plan clinic and explore aerosol settling time after dental procedures.

Methods

In two experimental designs using simulated dental procedures on a mannequin, fluorescein dye was introduced: (1) into the irrigation system of an air-turbine handpiece; (2) into the mannequin's mouth. Filter papers were placed in an open plan clinic to collect fluorescein. An 8-metre diameter rig was used to investigate aerosol settling time. Analysis was by fluorescence photography and spectrofluorometry.

Results

Contamination distribution varied across the clinic depending on conditions. Unmitigated procedures have the potential to deposit contamination at large distances. Medium volume dental suction (159 L/min air) reduced contamination in the procedural bay by 53%, and in other areas by 81-83%. Low volume suction (40 L/min air) was similar. Cross-ventilation reduced contamination in adjacent and distant areas by 80-89%. In the most realistic model (fluorescein in mouth, medium volume suction), samples in distant bays (≥5 m head-to-head chair distance) gave very low or zero readings (< 0.0016% of the fluorescein used during the procedure). Almost all (99.99%) of the splatter detected was retained within the procedural bay/walkway. After 10 min, very little additional aerosol settled.

Conclusions

Cross-infection risk from dental procedures in an open plan clinic appears small when bays are ≥ 5 m apart. Dilution effects from instrument water spray were observed, and dental suction is of benefit. Most settled aerosol is detected within 10 min indicating environmental cleaning may be appropriate after this. Clinical Significance: Aerosols produced by dental procedures have the potential to contaminate distant sites and the majority of settled aerosol is detectable after 10 min. Dental suction and ventilation have a substantial beneficial effect. Contamination is likely to be minimal in open plan clinics at distances of 5 m or more.

Clinical dental students' knowledge regarding proper dental settings for treating patient during COVID-19: A cross-sectional study

Objectives:

To investigate the clinical dental students’ knowledge on the proper dental setting during COVID-19.

Methods:

Using multicenter cross-sectional study, a 10-items questionnaire was distributed in April 2020 among senior dental students from two dental schools. It comprised three main domains: demographic questions, questions investigating student’s access to the proper recommendations of dental settings during COVID-19 and the specific recommendations questions.

Results:

The questionnaire was sent to 654 clinical dental students and the total number of respondents were 267 representing a response rate of 40.83%. The overall knowledge mean was low (1±0.92). Gender was not a statistically significant factor affecting the knowledge score (P > 0.05). Most of the participants never visited the Saudi Center for Disease Prevention and Control (Saudi CDC) website and received no guidance or advice regarding proper dental practices during COVID-19. A statistically significant relationship was observed between the mean knowledge score and access to knowledge variables (P < 0.05).

Conclusion:

It was noted that clinical dental students have low knowledge on the proper dental settings during COVID-19 pandemic that was recommended by the Saudi CDC guidelines and they must be equipped with adequate knowledge from reliable sources to overcome their insufficiencies such as a well-structured and dynamic curriculum.

Aerosol transmission for SARS-CoV-2 in the dental practice. A review by SIdP Covid-19 task-force

Current evidence suggests that SARS-CoV-2, the virus that causes COVID-19, is predominantly spread from person to person. Aim of this narrative review is to explore transmission modality of SARS-CoV-2 to provide appropriate advice to stakeholders, in order to support the implementation of effective public health measures and protect healthcare workers that primary face the disease. "In vivo" and "in vitro" studies from laboratories and hospitals confirmed the presence of surface contamination and provided insight of SARS-CoV-2 detection in the air, particularly in indoor settings with poor ventilation where aerosol-generating procedures were performed. Measures for aerosol reduction, in conjunction with other effective infection control strategies, are needed to prevent the spread of SARS-CoV-2 in dental setting.

Evaluating aerosol and splatter following dental procedures: Addressing new challenges for oral health care and rehabilitation

BACKGROUND

Dental procedures often produce aerosol and splatter which have the potential to transmit pathogens such as SARS-CoV-2. The existing literature is limited.

OBJECTIVE(S)

To develop a robust, reliable and valid methodology to evaluate distribution and persistence of dental aerosol and splatter, including the evaluation of clinical procedures.

METHODS

Fluorescein was introduced into the irrigation reservoirs of a high-speed air-turbine, ultrasonic scaler and 3-in-1 spray, and procedures were performed on a mannequin in triplicate. Filter papers were placed in the immediate environment. The impact of dental suction and assistant presence were also evaluated. Samples were analysed using photographic image analysis and spectrofluorometric analysis. Descriptive statistics were calculated and Pearson's correlation for comparison of analytic methods.

RESULTS

All procedures were aerosol and splatter generating. Contamination was highest closest to the source, remaining high to 1-1.5 m. Contamination was detectable at the maximum distance measured (4 m) for high-speed air-turbine with maximum relative fluorescence units (RFU) being: 46,091 at 0.5 m, 3,541 at 1.0 m and 1,695 at 4 m. There was uneven spatial distribution with highest levels of contamination opposite the operator. Very low levels of contamination (≤0.1% of original) were detected at 30 and 60 minutes post-procedure. Suction reduced contamination by 67-75% at 0.5-1.5 m. Mannequin and operator were heavily contaminated. The two analytic methods showed good correlation (r = 0.930, n = 244, P < .001).

CONCLUSION

Dental procedures have potential to deposit aerosol and splatter at some distance from the source, being effectively cleared by 30 minutes in our setting.

COVID-19 transmission risk and protective protocols in dentistry: a systematic review

Background

Among several potential transmission sources in the spreading of the COVID-19, dental services have received a high volume of attention. Several reports, papers, guidelines, and suggestions have been released on how this infection could be transmitted through dental services and what should be done. This study aimed to review the guidelines in order to develop a practical feasibility protocol for the re-opening of dental clinics and the reorientation of dental services.

Methods

This study systematically reviewed the published literature and the guidelines of international health care institutions on dentistry and COVID-19. We searched Pubmed, Web of Science, and SCOPUS electronic databases using MESH terms. The recommendations identified were tested with a convenience sample of experienced practitioners, and a practical step-by-step protocol is presented in this paper.

Results

To the date this paper was drafted, 38 articles were found, of which 9 satisfied our inclusion criteria. As all the nine studies were proposed in a general consensus, any elective non-emergency dental care for patients with suspected or known COVID-19 should be postponed for at least 2 weeks during the COVID-19 pandemic. Only urgent treatment of dental diseases can be performed during the COVID-19 outbreak taking into consideration pharmacological management as the first line and contagion-reduced minimally invasive emergency treatment as the secondary and final management.

Conclusions

While the currently available evidence has not demonstrated a clear and direct relationship between dental treatment or surgery and the possibility of the transmission of COVID-19, there is clearly the potential for transmission. Therefore, following the protective protocols in the COVID-19 crisis is of utmost importance in a dental setting.

Aerosol-Generating Procedures and Simulated Cough in Dental Anesthesia

Dental professionals are at an increased risk for exposure to the severe acute respiratory syndrome coronavirus 2 with aerosol-generating procedures (AGPs), and dental anesthesia practices have additional risks due to airway management procedures. The purpose of this pilot study was to examine the extent of splatter on dental personnel that may occur with AGPs and coughing in a dental anesthesia practice. A Dentoform model was fitted into a dental mannequin and coated with Glo Germ to detect splatter during simulated dental AGPs produced with use of a high-speed handpiece, an ultrasonic scaler, and an air-water syringe, all in conjunction with high-volume suction. A simulated cough was also created using a ventilator programmed to expel Glo Germ within the velocity and volume parameters of a natural cough with dental personnel in their customary positions. A UV light was used after each procedure to systematically evaluate the deposition of Glo Germ splatter on each person. After AGPs were performed, splatter was noted on the face, body, arms, and legs of the dentist and dental assistant. The simulated cough produced more extensive splatter than AGPs; additional Glo Germ was seen on the shoes, the crown of the head, and the back of the dental personnel. Therefore, it is recommended that full personal protective equipment consistent with AGPs be used and changed between patients to reduce the risk of contamination and infection for dental personnel and patients.

Demystifying the mist: Sources of microbial bioload in dental aerosols

The risk of transmitting airborne pathogens is an important consideration in dentistry and has acquired special significance in the context of recent respiratory disease epidemics. The purpose of this review, therefore, is to examine (1) what is currently known regarding the physics of aerosol creation, (2) the types of environmental contaminants generated by dental procedures, (3) the nature, quantity, and sources of microbiota in these contaminants and (4) the risk of disease transmission from patients to dental healthcare workers. Most dental procedures that use ultrasonics, handpieces, air‐water syringes, and lasers generate sprays, a fraction of which are aerosolized. The vast heterogeneity in the types of airborne samples collected (spatter, settled aerosol, or harvested air), the presence and type of at‐source aerosol reduction methods (high‐volume evacuators, low volume suction, or none), the methods of microbial sampling (petri dishes with solid media, filter paper discs, air harvesters, and liquid transport media) and assessment of microbial bioload (growth conditions, time of growth, specificity of microbial characterization) are barriers to drawing robust conclusions. For example, although several studies have reported the presence of microorganisms in aerosols generated by ultrasonic scalers and high‐speed turbines, the specific types of organisms or their source is not as well studied. This paucity of data does not allow for definitive conclusions to be drawn regarding saliva as a major source of airborne microorganisms during aerosol generating dental procedures. Well‐controlled, large‐scale, multi center studies using atraumatic air harvesters, open‐ended methods for microbial characterization and integrated data modeling are urgently needed to characterize the microbial constituents of aerosols created during dental procedures and to estimate time and extent of spread of these infectious agents.

Precautions and recommendations for orthodontic settings during the COVID-19 outbreak: A review

Introduction

Coronavirus disease 2019 (COVID-19) is a contagious disease caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2). It emerged as a global pandemic in early 2020, affecting more than 200 countries and territories. The infection is highly contagious, with disease transmission reported from asymptomatic carriers, including children. It spreads through person-to-person contact via aerosol and droplets. The practice of social distancing—maintaining a distance of 1-2 m or 6 ft—between people has been recommended widely to slow or halt the spread. In orthodontics, this distance is difficult to maintain, which places orthodontists at a high risk of acquiring and transmitting the infection. The objective of this review is to report to orthodontists on the emergence, epidemiology, risks, and precautions during the disease crisis. This review should help increase awareness, reinforce infection control, and prevent cross-transmission within the orthodontic facility.

Methods

A comprehensive literature review of English and non-English articles was performed in March 2020 using COVID-19 Open Research Dataset (CORD-19 2020), PubMed, MEDLINE, Scopus, and Google Scholar to search for infection control and disease transmission in orthodontics.

Results

This review emphasizes minimizing aerosol production and reinforcing strict infection control measures. Compliance with the highest level of personal protection and restriction of treatment to emergency cases is recommended during the outbreak. Surface disinfection, adequate ventilation, and decontamination of instruments and supplies following the guidelines are required.

Conclusions

Reinforcing strict infection control measures and minimizing personal contact and aerosol production are keys to prevent contamination within orthodontic settings. Although no cases of COVID-19 cross-transmission within a dental facility have been reported, the risk exists, and the disease is still emerging. Further studies are required.

•

Coronavirus disease 2019 is a highly contagious global pandemic.

•

It could transmit by asymptomatic carriers via person-to-person contact, aerosol, and droplets.

•

Strict infection control and aerosol containment are required in orthodontic settings.

Bioaerosol in dental prosthodontics

Introdution: During many dental interventions, performed using handpiece instruments and pusters, an aerosol is created,which is converted into a bioaerosol (BIOA) by mixing with the particles of various organic components from the patient's oral cavity.When the high-speed mashine is started, the air becomes instantly contaminated and practically covers the entire room. Pollution is registered all the times, as well as after prosthetic treatment. BIOA created during prosthetic workcontains various bacteria, fungi and viruses from the patient's oral cavity. These microorganisms pose a real hazard to health workers and are a potential risk for infection. The most common pathogens include influenza viruses, herpes viruses, as well as pathogenic streptococci and staphylococci. Infectious diseases, biosynosis, acute toxic reactions, allergies, atopic diseases, conjunctivitis, contact dermatitis, infections of the respiratory system, and even some types of cancer, are possible manifestations of side effects of BIOA. Conclusion:BIOA poses a potential danger to contamination of air, work surfaces and objects in dental offices. Direct and indirect exposure of dental staff and patients to BIOA is especially pronounced in the conditions of COVID 19. Although it is impossible to completely eliminate the risk of adverse effects of BIOA, it is important to pay attention to all prevention measures that can reduce the likelihood of contamination.

Do exposures to aerosols pose a risk to dental professionals?

Background

Dental care professionals are exposed to aerosols from the oral cavity of patients containing several pathogenic microorganisms. Bioaerosols generated during dental treatment are a potential hazard to dental staff, and there have been growing concerns about their role in transmission of various airborne infections and about reducing the risk of contamination.

Aims

To investigate qualitatively and quantitatively the bacterial and fungal aerosols before and during clinical sessions in two dental offices compared with controls.

Methods

An extra-oral evacuator system was used to measure bacterial and fungal aerosols. Macroscopic and microscopic analysis of bacterial species and fungal strains was performed and strains of bacteria and fungi were identified based on their metabolic properties using biochemical tests.

Results

Thirty-three bioaerosol samples were obtained. Quantitative and qualitative evaluation showed that during treatment, there is a significant increase in airborne concentration of bacteria and fungi. The microflora included mainly gram-positive organisms (Staphylococcus epidermidis and Micrococcus spp.), gram-positive rod-shaped bacteria and those creating endospores as well as non-porous bacteria and mould fungi (Cladosporium and Penicillium).

Conclusions

Exposure to the microorganisms identified is not a significant occupational hazard for dental care professionals; however, evidence-based prevention measures are recommended.

Knowledge and Attitude of Dental Health Professionals about Middle East Respiratory Syndrome in Saudi Arabia

Aim and Objective

This study aims to evaluate the knowledge and attitude of practicing dental health professionals (DHPs) (dentist and dental auxiliaries) toward Middle East Respiratory Syndrome coronavirus (MERS-CoV) in Saudi Arabia.

Materials and Methods

A cross-sectional descriptive study was undertaken among practicing DHPs in Saudi Arabia. A total of 202 DHPs participated in this study. Knowledge and attitude were assessed using self-administered and pretested questionnaire. The questionnaire was administered online through Survey Monkey^® program by sending link to the registered E-mail. Descriptive statistics were performed on demographic data. Mean knowledge and mean attitude scores of DHPs were calculated. Mann-Whitney U-test and Kruskal-Wallis tests were used to disclose the differences between study variables. Chi-square tests and Spearman's correlation tests were applied to find the associations between the variables.

Results

The study participants showed mean knowledge score of 12.26 ± 2.27 (based on 17 knowledge questions) and attitude score of 8.63 ± 1.68 (based on 10 attitude questions). The spearman's test showed the positive correlation between knowledge and attitude of DHPs about MERS (r = 0.093, P = 0.188). Knowledge gaps were reflected in questions related to the duration of infectivity (47.5%), treatment of MERS (39.6%), reservoir of MERS-CoV (38.1%), availability of vaccination against MERS-CoV (25.2%), the likelihood of infection (24.3%), and the type of MERS-CoV (23.3%). DHPs showed a positive attitude toward adherence to universal precautions given by CDC and WHO (0.94 ± 0.25), active participation infection control program (0.94 ± 0.24), and use of gowns, gloves, mask, and goggles while dealing with MERS-CoV patients (0.97 ± 0.17). Male DHPs showed significantly higher knowledge and positive attitude toward MERS-CoV infection compared to females.

Conclusion

DHPs participated in this study showed good knowledge and positive attitude toward MERS. However, still few lacunae in the knowledge and attitudes toward MERS-CoV were found requiring extensive educational programs.

Middle East respiratory syndrome in children. Dental considerations

As of January 2016, 1,633 laboratory-confirmed cases of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) infection and 587 MERS-related deaths have been reported by the World Health Organization globally. Middle East Respiratory Syndrome Coronavirus may occur sporadically in communities or may be transmitted within families or hospitals. The number of confirmed MERS-CoV cases among healthcare workers has been increasing. Middle East Respiratory Syndrome Coronavirus may also spread through aerosols generated during various dental treatments, resulting in transmission between patients and dentists. As MERS-CoV cases have also been reported among children, pediatric dentists are at risk of MERS-CoV infection. This review discusses MERS-CoV infection in children and healthcare workers, especially pediatric dentists, and considerations pertaining to pediatric dentistry. Although no cases of MERS-CoV transmission between a patient and a dentist have yet been reported, the risk of MERS-CoV transmission from an infected patient may be high due to the unique work environment of dentists (aerosol generation).

A scoping review on bio-aerosols in healthcare and the dental environment

Background

Bio-aerosols originate from different sources and their potentially pathogenic nature may form a hazard to healthcare workers and patients. So far no extensive review on existing evidence regarding bio-aerosols is available.

Objectives

This study aimed to review evidence on bio-aerosols in healthcare and the dental setting. The objectives were 1) What are the sources that generate bio-aerosols?; 2) What is the microbial load and composition of bio-aerosols and how were they measured?; and 3) What is the hazard posed by pathogenic micro-organisms transported via the aerosol route of transmission?

Methods

Systematic scoping review design. Searched in PubMed and EMBASE from inception to 09-03-2016. References were screened and selected based on abstract and full text according to eligibility criteria. Full text articles were assessed for inclusion and summarized. The results are presented in three separate objectives and summarized for an overview of evidence.

Results

The search yielded 5,823 studies, of which 62 were included. Dental hand pieces were found to generate aerosols in the dental settings. Another 30 sources from human activities, interventions and daily cleaning performances in the hospital also generate aerosols. Fifty-five bacterial species, 45 fungi genera and ten viruses were identified in a hospital setting and 16 bacterial and 23 fungal species in the dental environment. Patients with certain risk factors had a higher chance to acquire Legionella in hospitals. Such infections can lead to irreversible septic shock and death. Only a few studies found that bio-aerosol generating procedures resulted in transmission of infectious diseases or allergic reactions.

Conclusion

Bio-aerosols are generated via multiple sources such as different interventions, instruments and human activity. Bio-aerosols compositions reported are heterogeneous in their microbiological composition dependent on the setting and methodology. Legionella species were found to be a bio-aerosol dependent hazard to elderly and patients with respiratory complaints. But all aerosols can be can be hazardous to both patients and healthcare workers.

Assessment of airborne bacteria in selected occupational environments in Quezon City, Philippines

Exposure to bioaerosols has been associated with health deterioration among workers in several occupational environments. This highlights the need to study the microbiological quality of air of workplaces as no such study has been conducted yet in the Philippines. To detect and characterize the culturable mesophilic airborne bacteria in selected occupational environments we used passive sedimentation technique. It was observed that the number of colony-forming units was highest in junk shop, followed by the light railway transit station and last the office. By contrast, the bacterial composition was similar in all sites: Gram-positive cocci > Gram-positive bacilli > Gram-negative bacteria. Staphylococcus aureus and Bacillus spp. were also detected in all sites. These findings suggest that the presence of airborne bacteria may be a potential health hazard in urban occupational environments in the Philippines.

Dental unit waterlines disinfection using hypochlorous acid-based disinfectant

Objective:

The purpose of the study was to investigate the efficacy of a new disinfectant to disinfect the dental unit waterlines.

Materials and Methods:

New dental unit waterlines were installed in 13 dental chairs, and biofilm was allowed to grow for 10 days. Disinfection treatment procedure was carried out in the 12 units, and one unit was left untreated. The dental unit waterlines were removed and analyzed using the scanning electron microscope (SEM) (TESCAN VEGA3 SBU).

Result:

On examination, SEM images showed that there was no slime layer or bacterial cells seen in any of the 12 cut sections obtained from the treated dental waterlines which mean that there was no evident of biofilm formation. Untreated dental unit waterlines showed a microbial colonization with continuous filamentous organic matrix. There was significant biofilm formation in the control tube relative to the samples.

Conclusion:

The tested disinfectant was found to be effective in the removal of biofilm from the dental unit waterlines.

Non-culturable bioaerosols in indoor settings: Impact on health and molecular approaches for detection

Despite their significant impact on respiratory health, bioaerosols in indoor settings remain understudied and misunderstood. Culture techniques, predominantly used for bioaerosol characterisation in the past, allow for the recovery of only a small fraction of the real airborne microbial burden in indoor settings, given the inability of several microorganisms to grow on agar plates. However, with the development of new tools to detect non-culturable environmental microorganisms, the study of bioaerosols has advanced significantly. Most importantly, these techniques have revealed a more complex bioaerosol burden that also includes non-culturable microorganisms, such as archaea and viruses. Nevertheless, air quality specialists and consultants remain reluctant to adopt these new research-developed techniques, given that there are relatively few studies found in the literature, making it difficult to find a point of comparison. Furthermore, it is unclear as to how this new non-culturable data can be used to assess the impact of bioaerosol exposure on human health. This article reviews the literature that describes the non-culturable fraction of bioaerosols, focussing on bacteria, archaea and viruses, and examines its impact on bioaerosol-related diseases. It also outlines available molecular tools for the detection and quantification of these microorganisms and states various research needs in this field.

Efficacy versus health risks: An in vitro evaluation of power-driven scalers

Background:

Power-driven instrumentation of root surfaces during supportive periodontal therapy is an alternative to hand instrumentation. The purpose of this pilot in vitro study was to investigate the efficacy of sub- and supragingival plaque removal with a sonic (AIR: Synea, W and H, Bürmoos, Austria) and two ultrasonic devices (TIG: Tigon+, W and H, Bürmoos, Austria; VEC: Vector, Dürr, Bietigheim-Bissingen, Germany) as well as the health-risk for dental professionals during treatment.

Materials and Methods:

The power-driven devices were utilized to remove plaque from model teeth in dummy heads. The percentage of residual artificial plaque after 2 min of supra- or subgingival instrumentation was calculated by means of image-processing techniques at four sites (n = 576) of each tooth. The Health-Risk-Index (HRI: spatter/residual plaque quotient) with the different power-driven devices was assessed during treatment.

Results:

The smallest amounts of residual plaque were found for the sonic device AIR (8.89% ± 10.92%) and the ultrasonic scaler TIG (8.72% ± 12.02%) (P = 0.707). Significantly more plaque was remained after the use of the ultrasonic scaler VEC (18.76% ± 18.07%) (P < 0.001). Irrespectively of the scaler, efficacy was similar sub- (10.7% ± 11.6%) and supragingivally (13.5% ± 17.2%) (P = 0.901). AIR/TIG demonstrated equal residual amounts of plaque sub- (P = 0.831) as well as supragingivally (P = 0.510). However, AIR/VEC and TIG/VEC were significantly in favor of AIR and TIG (P < 0.001). In contrast, the lowest HRI was found after using VEC (0.0043) and differed considerably for AIR (0.2812) and TIG (0.0287).

Conclusion:

Sonic devices are as effective as ultrasonic devices in the removal of biofilm but bear a higher risk to the dental professional's health concerning the formation of spatter.

Endotoxin deposits on the inner surfaces of closed-face cassettes during bioaerosol sampling: a field investigation at composting facilities

A set of 270 bioaerosol samples was taken from 15 composting facilities using polystyrene closed-face filter cassettes (CFCs). The objective was to measure the quantity of endotoxin deposits on the inner surfaces of the cassettes (sometimes referred to as 'wall deposits'). The results show that endotoxins are deposited on the inner surfaces of the CFCs through sampling and/or handling of samples. The quantity of endotoxins measured on inner surfaces range between 0.05 (the limit of detection of the method) and 3100 endotoxin units per cassette. The deposits can represent a large and variable percentage of the endotoxins sampled. More than a third of the samples presented a percentage of inner surface deposits >40% of the total quantity of endotoxins collected (filter + inner surfaces). Omitting these inner surface deposits in the analytical process lead to measurement errors relative to sampling all particles entering the CFC sampler, corresponding to a developing consensus on matching the inhalable particulate sampling convention. The result would be underestimated exposures and could affect the decision as to whether or not a result is acceptable in comparison to airborne concentration limits defined in terms of the inhalability convention. The results of this study suggest including the endotoxins deposited on the inner surfaces of CFCs during analysis. Further researches are necessary to investigate endotoxin deposits on the inner cassette surfaces in other working sectors.

Microbial contamination of dental unit waterlines and effect on quality of indoor air

The microbiological quality in dental unit waterlines (DUWLs) is considered to be important because patients and dental staff with suppressed immune systems are regularly exposed to water and aerosols generated from dental units (DUs). Opportunistic pathogens like Pseudomonas, Legionella, Candida, and Aspergillus can be present in DUWLs, while during consultations, bioaerosols can be dispersed in the air, thus resulting in effects on microbiological quality of indoor air. This present study represents microbiological air and water quality in dental offices (DOs) and also concerns the relationship between the quality of DO air and dental unit water. This study aimed to assess both the microbial quality of dental unit water and the indoor air in 20 DOs and to survey the effect on the quality of the indoor air with the existing microorganisms in dental unit water. Fourteen out of 20 (70 %) DUWLs were found to be contaminated with a high number of aerobic mesophilic heterotrophic bacteria. In terms of bacterial air contamination levels, in 90 % of DOs, a medium level (<500 colony-forming units (CFU)/m(3)) of contamination was determined, while in terms of microfungal air contamination, in all DOs, a low level (<100 CFU/m(3)) of contamination was determined. Potential infection or allergen agents, such as Pseudomonas, Micrococcus, Staphylococcus, Alternaria, Cladosporium, Penicillium, Aspergillus, and Paecilomyces were isolated from water and air samples. This study's determination of contamination sources and evaluation of microbial load in DOs could contribute to the development of quality control methods in the future.

Indoor exposure to airborne endotoxin: a review of the literature on sampling and analysis methods

Assessment of exposure to airborne endotoxins has been studied for several years, especially in occupational environments, but a large number of procedures are used for sampling and analysis. This lack of standardization makes it very difficult to compare results and set internationally accepted threshold limit values (TLVs) or occupational exposure limits (OELs) for endotoxin exposure. This paper reviews the methods reported, using advanced bibliographical search techniques: 82 papers published from 2004 to the present were selected to analyze methods for the assessment of human exposure to airborne endotoxins, with particular reference to occupational settings, and to examine their performance and critical points. Only few studies have focused on the standardization of sampling and analysis methods. The European Committee for Standardization Guidelines coincide with the procedures most frequently applied, but this does not guarantee the best results in terms of recovery and reproducibility. The factor that mainly affects endotoxin measurements is the extraction method, the main concern being the presence in the samples of a fraction insoluble in aqueous media. If substantial differences in the proportions of this fraction in different environments are confirmed in the future, the contribution of insoluble endotoxins cannot be neglected.

Size distribution of airborne fungi in vehicles under various driving conditions

Circulation or air conditioning (AC) system was proven to improve the air quality inside the vehicles; however, the quantified study was limited. In this study, fungal concentration under various driving mode inside the vehicle was proposed. The driving conditions were classified into 4 states: (1) window closed without AC and circulation, (2) window open without AC and circulation, (3) window closed with only circulation on, and (4) window closed with only AC on. Results show that at state 4, the mean respirable fraction was 83.3%, with a number median diameter of the fungi being 1.73 μm. More attention should be paid for these smaller fungi easily penetrating into the alveoli and probably lead to allergic alveolitis. Turning on AC for reducing the normalized concentration for each size range of fungi was suggested; however, the respirable fraction increased. Those who are prone to allergies or asthma are suggested to switch between AC and the circulation mode while driving a long time.

Risk factors associated with asthma phenotypes in dental healthcare workers

BACKGROUND

Exposure in the dental environment can increase the risk of respiratory disease in dental healthcare workers (HCWs). This study investigated the prevalence of asthma phenotypes in dental HCWs and associated risk factors.

METHODS

A cross-sectional study of 454 dental HCWs in five dental institutions in South Africa was conducted. A self-administered questionnaire elicited the health and employment history of subjects. Sera was analyzed for atopic status and latex sensitization. Pre- and post-bronchodilator spirometry was performed.

RESULTS

The prevalence of atopic asthma was 6.9%, non-atopic asthma 5.9% and work-exacerbated asthma (WEA) 4.0%. Atopy and work-related ocular-nasal symptoms were strong predictors of WEA (OR: 3.4; 95% CI: 1.07-10.8; OR: 6.7, 95% CI: 2.4-19.1), respectively. Regular use of personal protective equipment (PPE) was associated with a protective affect (OR: 0.23, 95% CI: 0.1-0.7) among non-atopic asthmatics, while glove use and respiratory protection was protective among atopic asthmatics (OR: 0.39, 95% CI: 0.17-0.89).

CONCLUSION

Identification of risk factors associated with specific asthma phenotypes in dental HCWs can be used to focus preventive strategies for asthmatics.

Measurement of endotoxins in bioaerosols at workplace: a critical review of literature and a standardization issue

Endotoxins are lipopolysaccharides found in the outer membrane of most Gram-negative bacteria and cyanobacteria. Worker exposure to endotoxins has been shown in a number of work situations and is associated with both respiratory and systemic pathologies. The lack of an occupational exposure limit is mainly due to the absence of a standard protocol at the international level for sampling and analyzing airborne endotoxins. The bibliographic review in this article takes an exhaustive look at the current knowledge on measuring airborne endotoxins. It shows that, despite several reference documents at the international level, the methods used to measure endotoxin exposure differ considerably from one laboratory to another. Standardization is necessary to reduce interlaboratory variability and, ultimately, to improve the use of interstudy data. The bibliographic review presents the current status of standardization for airborne endotoxin measurement methods in the workplace and summarizes areas for further research. This article is both a reference document for all operators wishing to use such methods and a working document to build international consensus around the measurement of airborne endotoxins.

Evaluation of bacterial contaminants found on unused paper towels and possible postcontamination after handwashing: a pilot study

BACKGROUND

Bacterial contamination is a concern in the pulp and paper industry. Not only is the machinery contaminated but also can be the end-paper products. Bacterial transmission from unused paper towels to hands and surfaces is not well documented.

METHODS

The culturable bacterial community of 6 different unused paper towel brands was determined by culture methods and by sequencing the 16S ribosomal DNA of bacterial contaminants. Next, we investigated the possible airborne and direct contact transmissions of these bacterial contaminants during hand drying after washing.

RESULTS

Between 10(2) and 10(5) colony-forming units per gram of unused paper towels were isolated from the different paper towel brands. Bacteria belonging to the Bacillus genus were by far the most abundant microorganisms found (83.0%), followed by Paenibacillus (15.6%), Exiguobacterium (1.6%), and Clostridium (0.01%). Paper towels made from recycled fibers harbored between 100- to 1,000-fold more bacteria than the virgin wood pulp brand. Bacteria were easily transferred to disposable nitrile gloves when drying hands with paper towels. However, no evidence of bacterial airborne transmission was observed during paper towel dispensing.

CONCLUSION

This pilot study demonstrated that a large community of culturable bacteria, including toxin producers, can be isolated from unused paper towels and that they may be transferred to individuals after handwashing. This may have implications in some industrial and clinical settings as well as in immunocompromised individuals.

Immunogenic properties of archaeal species found in bioaerosols

The etiology of bioaerosol-related pulmonary diseases remains poorly understood. Recently, archaea emerged as prominent airborne components of agricultural environments, but the consequences of airway exposure to archaea remain unknown. Since subcomponents of archaea can be immunogenic, we used a murine model to study the pulmonary immune responses to two archaeal species found in agricultural facilities: Methanobrevibacter smithii (MBS) and Methanosphaera stadtmanae (MSS). Mice were administered intranasally with 6.25, 25 or 100 µg of MBS or MSS, once daily, 3 days a week, for 3 weeks. MSS induced more severe histopathological alterations than MBS with perivascular accumulation of granulocytes, pronounced thickening of the alveolar septa, alveolar macrophages accumulation and increased perivascular mononucleated cell accumulation. Analyses of bronchoalveolar lavage fluids revealed up to 3 times greater leukocyte accumulation with MSS compared to MBS. Instillation of 100 µg of MBS or MSS caused predominant accumulation of monocyte/macrophages (4.5×10(5) and 4.8×10(5) cells/ml respectively) followed by CD4(+) T cells (1.38×10(5) and 1.94×10(5) cells/ml respectively), B cells (0.73×10(5) and 1.28×10(5) cells/ml respectively), and CD8(+) T cells (0.20×10(5) and 0.31×10(5) cells/ml respectively) in the airways. Both archaeal species induced similar titers of antigen-specific IgGs in plasma. MSS but not MBS caused an accumulation of eosinophils and neutrophils in the lungs, which surprisingly, correlated inversely with the size of the inoculum. Stronger immunogenicity of MSS was confirmed by a 3 fold higher accumulation of myeloid dendritic cells in the airways, compared to MBS. Thus, the dose and species of archaea determine the magnitude and nature of the pulmonary immune response. This is the first report of an immunomodulatory role of archaeal species found in bioaerosols.

Workplace determinants of endotoxin exposure in dental healthcare facilities in South Africa

OBJECTIVES

Aerosols generated during dental procedures have been reported to contain endotoxin as a result of bacterial contamination of dental unit water lines. This study investigated the determinants of airborne endotoxin exposure in dental healthcare settings.

METHODS

The study population included dental personnel (n = 454) from five academic dental institutions in South Africa. Personal air samples (n = 413) in various dental jobs and water samples (n = 403) from dental handpieces and basin taps were collected. The chromogenic-1000 limulus amebocyte lysate assay was used to determine endotoxin levels. Exposure metrics were developed on the basis of individually measured exposures and average levels within each job category. Analysis of variance and multivariate linear regression models were constructed to ascertain the determinants of exposure in the dental group.

RESULTS

There was a 2-fold variation in personal airborne endotoxin from the least exposed (administration) to the most exposed (laboratory) jobs (geometric mean levels: 2.38 versus 5.63 EU m(-3)). Three percent of personal samples were above DECOS recommended exposure limit (50 EU m(-3)). In the univariate linear models, the age of the dental units explained the most variability observed in the personal air samples (R(2) = 0.20, P < 0.001), followed by the season of the year (R(2) = 0.11, P < 0.001). Other variables such as institution and total number of dental units per institution also explained a modest degree of variability. A multivariate model explaining the greatest variability (adjusted R(2) = 0.40, P < 0.001) included: the age of institution buildings, total number of dental units per institution, ambient temperature, ambient air velocity, endotoxin levels in water, job category (staff versus students), dental unit model type and age of dental unit.

CONCLUSIONS

Apart from job type, dental unit characteristics are important predictors of airborne endotoxin levels in this setting.