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

COVID-19 case management in primary dental care settings in Yorkshire and the Humber

Introduction Emerging guidance during the COVID-19 pandemic aimed to minimise transmission risk within dental settings. This service evaluation provides an overview of reported cases of COVID-19 among primary dental care staff within Yorkshire and the Humber.Methods Data for COVID-19 cases reported within dental practices between November 2020 and August 2021 were extracted from the Public Health England, Health Protection Zone database and summarised using descriptive statistics.Results In total, 421 cases across 223 dental practices were reported, with 221 close contacts and 77 outbreaks identified. Cases/contacts were highest among dental nurses (51/49%). Household and community (42/22%) were the most frequently reported sources of transmission, with the majority of staff-to-staff contacts (60%) occurring in communal/non-clinical areas.Discussion There was a low number of reported COVID-19 cases/contacts among dental professionals, with most cases suspected to have acquired the infection from outside of the dental setting. The majority of personal protective equipment breaches occurred within communal/non-clinical areas. When infection prevention and control guidance was followed, there were no incidences of staff or patients becoming contacts or cases.Conclusion With adherence to strict protocols, the risk of COVID-19 transmission in the dental setting was low within the context of this review. The evaluation highlighted the importance of collaborative working during the pandemic.

Precise control of digital dental unit to reduce aerosol and splatter production: new challenges for future epidemics

BACKGROUND

During dental procedures, critical parameters, such as cooling condition, speed of the rotary dental turbine (handpiece), and distance and angle from pollution sources, were evaluated for transmission risk of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), simulated by spiking in a plasmid encoding a modified viral spike protein, HexaPro (S6P), in droplets and aerosols.

METHODS

To simulate routine operation in dental clinics, dental procedures were conducted on a dental manikin within a digital dental unit, incorporating different dental handpiece speeds and cooling conditions. The tooth model was immersed in Coomassie brilliant blue dye and was pre-coated with 100 μL water spiked-in with S6P-encoding plasmid. Furthermore, the manikin was surrounded by filter papers and Petri dishes positioned at different distances and angles. Subsequently, the filter papers and Petri dishes were collected to evaluate the aerosol splash points and the viral load of S6P-encoding plasmid in aerosols and splatters generated during the dental procedure.

RESULTS

Aerosol splashing generated a localized pollution area extended up to 60 cm, with heightened contamination risks concentrated within a 30 cm radius. Significant differences in aerosol splash points and viral load by different turbine handpiece speeds under any cooling condition (P < 0.05) were detected. The highest level of aerosol splash points and viral load were observed when the handpiece speed was set at 40,000 rpm. Conversely, the lowest level of aerosol splash point and viral load were found at a handpiece speed of 10,000 rpm. Moreover, the aerosol splash points with higher viral load were more prominent in the positions of the operator and assistant compared to other positions. Additionally, the position of the operator exhibited the highest viral load among all positions.

CONCLUSIONS

To minimize the spread of aerosol and virus in clinics, dentists are supposed to adopt the minimal viable speed of a dental handpiece with limited cooling water during dental procedures. In addition, comprehensive personal protective equipment is necessary for both dental providers and dental assistants.

Detection of Visually Imperceptible Blood Contamination in the Surgical Area Using Luminol Among Different Oral Surgical Procedures: An Observational Study

Introduction Oral surgeons often encounter a significant occupational risk of exposure to potentially harmful infectious diseases during minor oral surgical procedures. These diseases can be transmitted through direct contact with body fluids and aerosolized splatters that may not be visibly detectable. The likelihood of transmission is heightened for clinicians, healthcare workers, and patients alike. The reported prevalence of exposure to blood-borne infections in this field is as high as 90%, with half of these exposures being visually imperceptible. Aim The aim was to detect visually imperceptible blood contamination on personal protective equipment (PPE) and clinical surfaces using the chemiluminescence agent luminol during oral surgical procedures. Materials and methods Thirty minor oral surgical procedures were performed in the Oral and Maxillofacial Surgery Department after obtaining approval from the Institutional Ethics Committee (IEC), Vinayaka Mission's Sankarachariyar Dental College, Vinayaka Mission's Research Foundation, Salem, India. The surgeon, assistant, patient, and clinical surfaces (comprising 15 subsites within the surgical field) wore PPE. The PPE was scrutinized for traces of visually imperceptible blood contamination using luminol. The results of blood splatter on PPE and clinical surfaces in different oral surgical procedures between the non-aerosol and aerosol groups of different durations were analyzed statistically using the chi-square test with p < 0.05 considered significant. Results We observed that visually imperceptible blood contamination in non-aerosol procedures was detected on the assistant PPE kit (46.7%, n = 14), assistant face shield (40%, n = 12), suction apparatus (50%, n = 15), wall (30%, n = 9), and floor (56.7%, n = 17), in both aerosol and non-aerosol procedures. The p-value has been considered statistically significant at p < 0.05 between both the groups (aerosol and non-aerosol). Conclusion Our study results confirmed the presence of undetected blood spillage during aerosol procedures of 30 minutes and non-aerosol surgical procedures of more than 30 minutes over an area of 3.1 feet horizontally and 4.8 feet vertically. So, we strongly emphasize that PPE kits and face shields are mandatory for both surgeon and assistant while performing oral surgical procedures in order to prevent the risk of cross infections, proper infection prevention control protocol for the clinical surfaces also needs to be followed as a standard protocol in all operations.

Aerosol-generating procedures and associated control/mitigation measures: Position paper from the Canadian Dental Hygienists Association and the American Dental Hygienists' Association

Background

Since the outbreak of COVID-19, how to reduce the risk of spreading viruses and other microorganisms while performing aerosolgenerating procedures (AGPs) has become a challenging question within the dental and dental hygiene communities. The purpose of this position paper is to summarize the evidence of the effectiveness of various mitigation methods used to reduce the risk of infection transmission during AGPs in dentistry.

Methods

The authors searched 6 databases-MEDLINE, EMBASE, Scopus, Web of Science, Cochrane Library, and Google Scholar-for relevant scientific evidence published between January 2012 and December 2022 to answer 6 research questions about the risk of transmission, methods, devices, and personal protective equipment (PPE) used to reduce contact with microbial pathogens and limit the spread of aerosols.

Results

A total of 78 studies fulfilled the eligibility criteria. The literature on the risk of infection transmission including SARS-CoV-2 between dental hygienists and their patients is limited. Although several mouthrinses are effective in reducing bacterial contaminations in aerosols, their effectiveness against SARS-CoV-2 is also limited. The combined use of eyewear, masks, and face shields is effective in preventing contamination of the facial and nasal region while performing AGPs. High-volume evacuation with or without an intraoral suction, low-volume evacuation, saliva ejector, and rubber dam (when appropriate) have shown effectiveness in reducing aerosol transmission beyond the generation site. Finally, the appropriate combination of ventilation and filtration in dental operatories is effective in limiting the spread of aerosols.

Discussion and Conclusion

Aerosols produced during clinical procedures can pose a risk of infection transmission between dental hygienists and their patients. The implementation of practices supported by available evidence will ensure greater patient and provider safety in oral health settings. More studies in oral health clinical environments would shape future practices and protocols, ultimately to ensure the delivery of safe clinical care.

Visualization of droplets and aerosols in simulated dental treatments to clarify the effectiveness of oral suction devices

PURPOSE

The hazards of aerosols generated during dental treatments are poorly understood. This study aimed to establish visualization methods, discover conditions for droplets/aerosols generated in simulating dental treatments and identify the conditions for effective suction methods.

METHODS

The spreading area was evaluated via image analysis of the droplets/aerosols generated by a dental air turbine on a mannequin using a light emitting diode (LED) light source and high-speed camera. The effects of different bur types and treatment sites, reduction effect of intra-oral suction (IOS) and extra-oral suction (EOS) devices, and effect of EOS installation conditions were evaluated.

RESULTS

Regarding the bur types, a bud-shaped bur on the air turbine generated the most droplets/aerosols compared with round-shaped, round end-tapered, or needle-tapered burs. Regarding the treatment site, the area of droplets/aerosols produced by an air turbine from the palatal plane of the anterior maxillary teeth was significantly higher. The generated droplet/aerosol area was reduced by 92.1% by using IOS alone and 97.8% by combining IOS and EOS. EOS most effectively aspirated droplets/aerosols when placed close (10 cm) to the mouth in the vertical direction (0°).

CONCLUSIONS

The droplets/aerosols generated by an air turbine could be visualized using an LED light and a high-speed camera in simulating dental treatments. The bur shape and position of the dental air turbine considerably influenced droplet/aerosol diffusion. The combined use of IOS and EOS at a proper position (close and perpendicular to the mouth) facilitated effective diffusion prevention to protect the dental-care environment.

Quantitative assessment of aerosol contamination generated during tooth grinding with a speed-increasing handpiece

OBJECTIVES

Tooth grinding produces a significant amount of aerosol particles. The aim of this study was to quantitatively assess particle contamination produced from tooth grinding with a speed-increasing handpiece across a real-world clinical setting.

METHODS

All molar crowns were pretreated into cylinders with a uniform size. A novel computer-assisted numerical control system was used to parametrically study the bur speed: from 20,000 (20 K) to 200 K rpm at 20 K rpm intervals. 5-minute tooth grinding was performed in triplicate at each speed setting. Three online real-time particle counters (ORPC; TR-8301, TongrenCo.) were placed at 3 positions (0.5, 1, and 1.5 m) to evaluate particle production. All experimental instruments were controlled remotely. The data obtained were statistically analyzed using descriptive statistics and non-parametric tests (Scheirer-Ray-Hare and Kruskal-Wallis/ Dunn-Bonferroni tests, p < 0.05).

RESULTS

The concentration level of aerosol particles production during the grinding experiment was elevated above the control group for all conditions, and increased with bur speed at any location (the maximum peak, reaching 5.59 × 107 particles/m3, at 200 K and 1 m), with differences between conditions. The effect of speed on the increment of particles across different channels compared to the control group was statistically significant among locations (p < 0.001).

CONCLUSIONS

Statistically significant particle contamination was produced using a speed-increasing handpiece, but the contamination level for each experimental condition was reduced to baseline within 30 min, and most particles with a diameter greater than 1üm produced at low speeds (80 K or lower) tended to settle within 1 m.

CLINICAL RELEVANCE

Our study suggested that the use of a speed-increasing handpiece below 80 K and 30 min of fallow time may lead to an adequate reduction in the health effects of particle contamination.

The Standard Operating Procedures in COVID-19 Pandemic for Periodontal Aerosol-Generating Procedures: A Process Audit

OBJECTIVE

 This study aims to audit the process of patient management with aerosol-generating procedure (ultrasonic scaling) while adherence to the guidelines for health care workers (HCWs) during the coronavirus disease 2019 (COVID-19).

MATERIALS AND METHODS

 Audits records at the Department of Periodontology at University College of Medicine and Dentistry Hospital, Lahore, Pakistan were collected (prospectively) over the period of October 1 to November 30, 2020 (1st cycle) and December 14, 2020 to February 12, 2021 (2nd cycle). The audit was divided into three components based on the guidelines: (1) physical environment, (2) patients/appointments, and (3) COVID standard operating procedures related to HCWs.

RESULTS

 The recommended physical layout and procedural factors, as suggested by the guidelines for dental clinics, were observed during the first cycle of audit, and discrepancy of ventilation system was fixed after the first cycle. Audit team reported the observance of fallow time three times daily, which revealed 83.3% observance of fallow time.Later in the second cycle when the extraoral high-volume air evacuator was installed, the fallow time was reduced to 15 minutes and not only five procedural slots per day were created but fallow time was also observed 100% of the time.

CONCLUSION

 Following the standard guidelines resulted in more efficient working environment and lesser risk for HCWs while performing aerosol-generating procedures.

Particle generation and dispersion from high-speed dental drilling

OBJECTIVE

To investigate the characteristics of particle generation and dispersion during dental procedure using digital inline holography (DIH) METHODS: Particles at two locations, near-field and far-field, which represent the field closer to the procedure location and within 0.5 m from the procedure location respectively, are studied using two different DIH systems. The effect of three parameters namely rotational speed, coolant flow rate, and bur angle on particle generation and dispersion are evaluated by using 10 different operating conditions. The particle characteristics at different operating conditions are estimated from the holograms using machine learning-based analysis.

RESULTS

The particle concentration decreased by at least two orders of magnitude between the near-field and far-field locations across the 10 different operating conditions, indicating significant dispersion of the particles. High rotational speed is found to produce a larger number of smaller particles, while lower rotational speeds generate larger particles. Coolant flow rate is found to have a greater impact on particle transport to the far-field location. Irregular shape dental particles account for 29% of total particles at far-field location, with the majority of these irregular shape particles having diameters ranging from 12 to 18 μm.

CONCLUSIONS

All three parameters have significant effects on particle generation and dispersion, with rotational speed having a more significant influence on particle generation at near-field and coolant flow rate playing a more important role on particle transport to the far-field.

CLINICAL RELEVANCE

This study provides valuable insights on particle characteristics during high-speed drilling. It can help dental professionals minimize exposure risks for themselves and patients by optimizing clinical operating conditions.

A COVID-19 University-Based Dental Clinic Experience and Infection Control Protocol Modification for Safe Clinical Education

OBJECTIVES

 The aim of the study was to share our experience of the development and application of a modified infection control protocol at the Dental Teaching Hospital, Umm Al-Qura University (UQUDENT) during the second wave of the COVID-19 pandemic. A second aim was to evaluate the impact of the implemented strategies on preparations for future requirements in clinical dental education.

MATERIALS AND METHODS

 In this descriptive study, we evaluated the challenges facing dental practice and categorized them into four domains: challenges facing dental practice during the pandemic, the risk of acquiring COVID-19 infection, the design of student clinics, and the financial challenges. The impact of strategies established to deal with such challenges was studied by comparing the number of treated patients from September 1, 2020, to March 01, 2021, with the number treated during the same months pre-COVID-19. The COVID-19 polymerase chain reaction (PCR) confirmed students and health care workers (HCWs) were expressed in numbers and percentages in each category of the study group.

RESULTS

 Policies were set up to deal with the challenges in each domain, after training all the hospital personnel in mitigation of the spread of infection within the hospital. We left a non-working clinic between every two operating clinics, and the patient risk was assessed by triage scoring and health status checks by a Saudi mobile application at the entrance. The hospital delivered more personal protective equipment and obligated all students and HCWs to wear KN95 or N95 masks during procedures. Over 1,500 patients were treated during the study period with more than a 30% reduction in comparison to those in the pre-COVID-19 period, but only 20 UQUDENT personnel had confirmed COVID-19 infection, and all proved to be community-acquired by contact tracing.

CONCLUSION

 The measures implemented in this study proved effective. With the challenges and limited resources, UQUDENT managed to resume the operation of its dental clinics and training while preventing cross-infection, and it ensured that dental students graduated with the required competency. Sharing experiences between educational institutes will help to graduate safe competent practitioners.

Evaluating the microbial aerosol generated by dental instruments: addressing new challenges for oral healthcare in the hospital infection

BACKGROUND

Using a rotary instrument or ultrasonic instrument for tooth preparation is a basic operation in the dental clinic that can produce a significant number of droplets and aerosols. The dental droplet and aerosol can lead to the transfer of harmful germs. The goal of this study was to analyze the properties of microbiological aerosol created by droplets and aerosol generated by three common tooth-preparation instruments.

METHODS

Streptococcus mutans UA159 was used as the biological tracer to visualize the droplets and aerosols. The passive sampling method was used to map the three-dimensional spatial distribution and the six-stage Andersen microbial sampler (AMS) was used as the active sampling method to catch aerosol particles at a specific time.

RESULTS

The aerosol concentration is related to instruments, three-dimensional spatial distribution, and dissipation time. Most aerosols were generated by air turbines. More microorganisms are concentrated at the 1.5 m plane. The majority of the post dental procedure contamination was detected within the 0-10-min period and it decreased rapidly within 30 min.

CONCLUSION

This study is conducive to the proposal and improvement of relevant infection control measures in dental procedures and provides a basis for the assessment of measures, reducing the risk of nosocomial infection.

Quantifying strategies to minimize aerosol dispersion in dental clinics

Many dental procedures are aerosol-generating and pose a risk for the spread of airborne diseases, including COVID-19. Several aerosol mitigation strategies are available to reduce aerosol dispersion in dental clinics, such as increasing room ventilation and using extra-oral suction devices and high-efficiency particulate air (HEPA) filtration units. However, many questions remain unanswered, including what the optimal device flow rate is and how long after a patient exits the room it is safe to start treatment of the next patient. This study used computational fluid dynamics (CFD) to quantify the effectiveness of room ventilation, an HEPA filtration unit, and two extra-oral suction devices to reduce aerosols in a dental clinic. Aerosol concentration was quantified as the particulate matter under 10 µm (PM10) using the particle size distribution generated during dental drilling. The simulations considered a 15 min procedure followed by a 30 min resting period. The efficiency of aerosol mitigation strategies was quantified by the scrubbing time, defined as the amount of time required to remove 95% of the aerosol released during the dental procedure. When no aerosol mitigation strategy was applied, PM10 reached 30 µg/m3 after 15 min of dental drilling, and then declined gradually to 0.2 µg/m3 at the end of the resting period. The scrubbing time decreased from 20 to 5 min when the room ventilation increased from 6.3 to 18 air changes per hour (ACH), and decreased from 10 to 1 min when the flow rate of the HEPA filtration unit increased from 8 to 20 ACH. The CFD simulations also predicted that the extra-oral suction devices would capture 100% of the particles emanating from the patient's mouth for device flow rates above 400 L/min. In summary, this study demonstrates that aerosol mitigation strategies can effectively reduce aerosol concentrations in dental clinics, which is expected to reduce the risk of spreading COVID-19 and other airborne diseases.

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.

Microbial Air Contamination in a Dental Setting Environment and Ultrasonic Scaling in Periodontally Healthy Subjects: An Observational Study

The risk of microbial air contamination in a dental setting, especially during aerosol-generating dental procedures (AGDPs), has long been recognized, becoming even more relevant during the COVID-19 pandemic. However, individual pathogens were rarely studied, and microbial loads were measured heterogeneously, often using low-sensitivity methods. Therefore, the present study aimed to assess microbial air contamination in the dental environment, identify the microorganisms involved, and determine their count by active air sampling at the beginning (T0), during (T1), and at the end (T2) of ultrasonic scaling in systemically and periodontally healthy subjects. Air microbial contamination was detected at T0 in all samples, regardless of whether the sample was collected from patients treated first or later; predominantly Gram-positive bacteria, including Staphylococcus and Bacillus spp. and a minority of fungi, were identified. The number of bacterial colonies at T1 was higher, although the species found were similar to that found during the T0 sampling, whereby Gram-positive bacteria, mainly Streptococcus spp., were identified. Air samples collected at T2 showed a decrease in bacterial load compared to the previous sampling. Further research should investigate the levels and patterns of the microbial contamination of air, people, and the environment in dental settings via ultrasonic scaling and other AGDPs and identify the microorganisms involved to perform the procedure- and patient-related risk assessment and provide appropriate recommendations for aerosol infection control.

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.

Aerosol concentrations and size distributions during clinical dental procedures

Background

Suspected aerosol-generating dental instruments may cause risks for operators by transmitting pathogens, such as the SARS-CoV-2 virus. The aim of our study was to measure aerosol generation in various dental procedures in clinical settings.

Methods

The study population comprised of 84 patients who underwent 253 different dental procedures measured with Optical Particle Sizer in a dental office setting. Aerosol particles from 0.3 to 10 μm in diameter were measured. Dental procedures included oral examinations (N = 52), restorative procedures with air turbine handpiece (N = 8), high-speed (N = 6) and low-speed (N = 30) handpieces, ultrasonic scaling (N = 31), periodontal treatment using hand instruments (N = 60), endodontic treatment (N = 12), intraoral radiographs (N = 24), and dental local anesthesia (N = 31).

Results

Air turbine handpieces significantly elevated <1 μm particle median (p = 0.013) and maximum (p = 0.016) aerosol number concentrations as well as aerosol particle mass concentrations (p = 0.046 and p = 0.006) compared to the background aerosol levels preceding the operation. Low-speed dental handpieces elevated >5 μm median (p = 0.023), maximum (p = 0.013) particle number concentrations,> 5 μm particle mass concentrations (p = 0.021) and maximum total particle mass concentrations (p = 0.022). High-speed dental handpieces elevated aerosol concentration levels compared to the levels produced during oral examination.

Conclusions

Air turbine handpieces produced the highest levels of <1 μm aerosols and total particle number concentrations when compared to the other commonly used instruments. In addition, high- and low-speed dental handpieces and ultrasonic scalers elevated the aerosol concentration levels compared to the aerosol levels measured during oral examination. These aerosol-generating procedures, involving air turbine, high- and low-speed handpiece, and ultrasonic scaler, should be performed with caution.

Clinical significance

Aerosol generating dental instruments, especially air turbine, should be used with adequate precautions (rubber dam, high-volume evacuation, FFP-respirators), because aerosols can cause a potential risk for operators and substitution of air turbine for high-speed dental handpiece in poor epidemic situations should be considered to reduce the risk of aerosol transmission.

Ultrafine particles exposure is associated with specific operative procedures in a multi-chair dental clinic

Air quality in dental clinics is critical, especially in light of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic, given that dental professionals and patients are at risk of regular exposure to aerosols and bioaerosols in dental clinics. High levels of ultrafine particles (UFP) may be produced by dental procedures. This study aimed to quantify ultrafine particles (UFP) concentrations in a real multi-chair dental clinic and compare the levels of UFP produced by different dental procedures. The efficiency of a high-volume evacuator (HVE) in reducing the UFP concentrations during dental procedures was also assessed. UFP concentrations were measured both inside and outside of a dental clinic in Shanghai, China during a 12-day period from July to September 2020. Dental activities were recorded during working hours. The mean (±standard deviation) concentrations of indoor and outdoor UFP during the sampling period were 8,209 (±4,407) counts/cm³ and 15,984 (±7,977) counts/cm³, respectively. The indoor UFP concentration was much higher during working hours (10,057 ± 5,725 counts/cm³) than during non-working hours (7,163 ± 2,972 counts/cm³). The UFP concentrations increased significantly during laser periodontal treatment, root canal filling, tooth drilling, and grinding, and were slightly elevated during ultrasonic scaling or tooth extraction by piezo-surgery. The highest UFP concentration (241,136 counts/cm³) was observed during laser periodontal treatment, followed by root canal filling (75,034 counts/cm³), which showed the second highest level. The use of an HVE resulted in lower number concentration of UFP when drilling and grinding teeth with high-speed handpieces, but did not significantly reduce UFP measured during laser periodontal therapy. we found that many dental procedures can generate high concentration of UFP in dental clinics, which may have a great health impact on the dental workers. The use of an HVE may help reduce the exposure to UFP during the use of high-speed handpieces.

Droplet Distribution in a University Dental Clinic Setting: The Importance of High-Volume Evacuation

The purpose of this study is to compare droplet distribution during a piezoelectric ultrasonic debridement procedure using either high-volume or slow-volume evacuation. Droplet distribution during a crown preparation with slow-volume evacuation is also examined. Fluorescein dye is added to the water reservoir and the procedures are performed by a single operator for 15 min on a dental manikin with artificial upper and lower teeth. Placement of filter paper squares (10 cm × 10 cm) in radiating lines away from the oral cavity of the dental manikin allows for visualization of droplet dispersion. Results show minimal difference in the spread of the droplets between the two evacuators during the debridement procedure; however, the slow-volume evacuator produces a higher concentration of droplets than the high-volume evacuator. An even higher concentration of droplets in the vicinity of the dental chair is observed during the crown preparation procedure. This study recommends the use of a high-volume evacuator where possible during professional debridement and crown preparation to reduce contamination around the dental chair from potentially pathogenic microorganisms.

Aerosol reduction efficacy of different intra-oral suction devices during ultrasonic scaling and high-speed handpiece use

Background

The COVID-19 pandemic led to significant changes in the provision of dental services, aimed at reducing the spread of respiratory pathogens through restrictions on aerosol generating procedures (AGPs). Evaluating the risk that AGPs pose in terms of SARS-CoV-2 transmission is complex, and measuring dental aerosols is challenging. To date, few studies focus on intra-oral suction. This study sought to assess the effectiveness of commonly used intra-oral suction devices on aerosol mitigation.

Methods

Ultrasonic scaling and high-speed handpiece procedures were undertaken to generate aerosol particles. Multiple particle sensors were positioned near the oral cavity. Sensor data were extracted using single board computers with custom in-house Bash code. Different high-volume and low-volume suction devices, both static and dynamic, were evaluated for their efficacy in preventing particle escape during procedures.

Results

In all AGPs the use of any suction device tested resulted in a significant reduction in particle counts compared with no suction. Low-volume and static suction devices showed spikes in particle count demonstrating moments where particles were able to escape from the oral cavity. High-volume dynamic suction devices, however, consistently reduced the particle count to background levels, appearing to eliminate particle escape.

Conclusions

Dynamic high-volume suction devices that follow the path of the aerosol generating device effectively eliminate aerosol particles escaping from the oral cavity, in contrast to static devices which allow periodic escape of aerosol particles. Measuring the risk of SARS-CoV-2 transmission in a dental setting is multi-factorial; however, these data suggest that the appropriate choice of suction equipment may further reduce the risk from AGPs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02386-w.

Aerosol and splatter generation with rotary handpieces used in restorative and orthodontic dentistry: a systematic review

Introduction

The COVID-19 pandemic has caused major disruptions in dental care globally, in part due to the potential for contaminated aerosol to be generated by dental activities. This systematic review assesses the literature for changes in aerosol-contamination levels when rotary instruments are used, (1) as distance increases from patient’s mouth; (2) as time passes after the procedure; and (3) when using different types of handpieces.

Methods

The review methods and reporting are in line with PRISMA statements. A structured search was conducted over five platforms (September 2021). Studies were assessed independently by two reviewers. To be eligible studies had to assess changes in levels of aerosol contamination over different distances, and time points, with rotary hand instruments. Studies’ methodologies and the sensitivity of the contamination-measurement approaches were evaluated. Results are presented descriptively.

Results

From 422 papers identified, 23 studies were eligible. All investigated restorative procedures using rotary instruments and one study additionally looked at orthodontic bracket adhesive material removal. The results suggest contamination is significantly reduced over time and distance. However, for almost all studies that investigated these two factors, the sizes of the contaminated particles were not considered, and there were inconclusive findings regarding whether electric-driven handpieces generate lower levels of contaminated particles.

Conclusion

Aerosol contamination levels reduce as distances, and post-procedure times increase. However, there was sparce and inconsistent evidence on the clearing time and no conclusions could be drawn. High-speed handpieces produce significantly higher levels of contamination than slow-speed ones, and to a lesser extent, micro-motor handpieces. However, when micro-motor handpieces were used with water, the contamination levels rose and were similar to high-speed handpiece contamination levels.

Numerical simulation of air age in dental offices

Dental professionals are at high risk of exposure to communicable diseases during clinical practice, but many dental clinics provide clinical care in closed spaces. Therefore, it is essential to develop efficient ventilation methods in dental clinics that do not rely on natural ventilation. In this study, to clarify the factors that cause air retention in dental offices, we conducted computational flow dynamics simulations focusing on (1) the flow path from the entrance to the exhaust port and (2) the presence of partitions. A three-dimensional model of a dental clinic with three dental chairs was created, and simulations were conducted for scenarios with and without partitions with different entrance and exhaust port positions. Evaluation of these simulations on the basis of the age of air, an indicator of ventilation efficiency, showed that the value of the air age near the partition was locally high in the scenarios with partitions. In the scenarios where the exhaust port was located close to the entrance, the air age near the exhaust port was high, regardless of the presence of a partition. In addition to wearing protective clothing and sterilizing instruments, it is important to consider air quality improvement as a countermeasure against airborne and droplet infections, such as virus infections, in dental clinics.

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 Dental Care Facilities: Update to Current Management and Control Strategies Implementing New Technologies: A Comprehensive Review

The quality of indoor air in healthcare facilities, with an emphasis on dental offices, attracted the attention of the scientific community in the late 1960s. Since then, it has become evident that the indoor air quality is critical in modern dental care facilities for limiting the spread of airborne infections, including vaccine-preventable diseases, and a key component of safety for healthcare personnel and patients. In the past decades, the role of indoor air quality has also been recognized in non-healthcare facilities, given the increasing time spent indoors by humans. During the provision of dental care services, mainly in the field of restorative dentistry, high-speed dental handpieces emitting air and water are used, producing large quantities of aerosol and hovering inside the operations area. In modern dental offices, new devices emitting air/powder for cavities improvement and cleaning as well as for periodontal prophylactic cleaning and aesthetics are used. In addition, a new therapeutic protocol for the removal of bacterial biofilm, targeting treatment for peri-implant diseases and conditions using air-abrasive decontamination technology, has been introduced in daily dental practice. The aim of this non-systemic review is to present the current state of knowledge on the nature and dynamics of air splatters and to provide an update to management and control strategies in dental care facilities, focusing on air purification and ultraviolet devices proposed and used. The findings arising from the limited number of related published articles documenting the reduction in levels of particular matter 2.5 (PM_2.5), PM₁₀ and volatile organic compounds, allow us to conclude that the continuous operation of air purifiers during and after treatment, contributes considerably to the improvement of the indoor air quality in dental care facilities. Moreover, the utilization of air purifiers is highly recommended in dental practice to mitigate spread of infections, including vaccine-preventable diseases. Frequent cleaning and maintenance of the purifier sieves and filters and frequent renovation of the indoor air through physical ventilation by mean of open windows is imperative. More research on environmental contamination and particularly on viral contamination under real dental care conditions is needed.

Simulated and clinical aerosol spread in common periodontal aerosol-generating procedures

Objectives

This study evaluated particle spread associated with various common periodontal aerosol-generating procedures (AGPs) in simulated and clinical settings.

Materials and methods

A simulation study visualized the aerosols, droplets, and splatter spread with and without high-volume suction (HVS, 325 L/min) during common dental AGPs, namely ultrasonic scaling, air flow prophylaxis, and implant drilling after fluorescein dye was added to the water irrigant as a tracer. Each procedure was repeated 10 times. A complementary clinical study measured the spread of contaminated particles within the dental operatory and quantified airborne protein dispersion following 10 min of ultrasonic supragingival scaling of 19 participants during routine periodontal treatment.

Results

The simulation study data showed that air flow produced the highest amount of splatters and the ultrasonic scaler generated the most aerosol and droplet particles at 1.2 m away from the source. The use of HVS effectively reduced 37.5–96% of splatter generation for all three dental AGPs, as well as 82–93% of aerosol and droplet particles at 1.2 m for the ultrasonic scaler and air polisher. In the clinical study, higher protein levels above background levels following ultrasonic supragingival scaling were detected in fewer than 20% of patients, indicating minimal particle spread.

Conclusions

While three common periodontal AGPs produce aerosols and droplet particles up to at least 1.2 m from the source, the use of HVS is of significant benefit. Routine ultrasonic supragingival scaling produced few detectable traces of salivary protein at various sites throughout the 10-min dental operatory.

Clinical relevance

The likelihood of aerosol spread to distant sites during common periodontal AGPs is greatly reduced by high-volume suction. Clinically, limited evidence of protein contaminants was found following routine ultrasonic scaling, suggesting that the the majority of the contamination consisits of the irrigant rather than organic matter from the oral cavity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-022-04532-8.

Efficacy of dental evacuation systems for aerosol exposure mitigation in dental clinic settings

Dental personnel are ranked among the highest risk occupations for exposure to SARS-CoV-2 due to their close proximity to the patient's mouth and many aerosol generating procedures encountered in dental practice. One method to reduce aerosols in dental settings is the use of intraoral evacuation systems. Intraoral evacuation systems are placed directly into a patient's mouth and maintain a dry field during procedures by capturing liquid and aerosols. Although multiple intraoral dental evacuation systems are commercially available, the efficacy of these systems is not well understood. The objectives of this study were to evaluate the efficacy of four dental evacuation systems at mitigating aerosol exposures during simulated ultrasonic scaling and crown preparation procedures. We conducted real-time respirable (PM₄) and thoracic (PM₁₀) aerosol sampling during ultrasonic scaling and crown preparation procedures while using four commercially available evacuation systems: a high-volume evacuator (HVE) and three alternative intraoral systems (A, B, C). Four trials were conducted for each system. Respirable and thoracic mass concentrations were measured during procedures at three locations including (1) near the breathing zone (BZ) of the dentist, (2) edge of the dental operatory room approximately 0.9 m away from the mannequin mouth, and (3) hallway supply cabinet located approximately 1.5 m away from the mannequin mouth. Respirable and thoracic mass concentrations measured during each procedure were compared with background concentrations measured in each respective location. Use of System A or HVE reduced thoracic (System A) and respirable (HVE) mass concentrations near the dentist's BZ to median background concentrations most often during the ultrasonic scaling procedure. During the crown preparation, use of System B or HVE reduced thoracic (System B) and respirable (HVE or System B) near the dentist's BZ to median background concentrations most often. Although some differences in efficacy were noted during each procedure and aerosol size fraction, the difference in median mass concentrations among evacuation systems was minimal, ranging from 0.01 to 1.48 µg/m³ across both procedures and aerosol size fractions.

Top 50 covid and oral health articles: A 2021 altmetric analysis

Objectives

There is a world of information at our disposal, and it is increasingly difficult to transform this dull amount of data into knowledge. How to be constantly actualized? This study aims to create an altmetric list of the top 50 articles related to COVID-19 and oral health.

Methods

Research of terms COVID-19 and oral health was done using Dimensions app. Results were ranked in altmetric citations and analyzed through Microsoft Excel. Some tables and graphics were created. Graphical illustration of keywords was created using VOSviewer.

Results

Some interesting facts can be seen, like growing interest in dental aerosols, perspectives, and virucidal activity of some mouthwashes.

Conclusions

Altmetric analysis is a helpful manner to scientific updates, supplementing bibliometric analysis. A terrific manner to see trends. The scientific community goes to great lengths to solve problems with dental aerosols, particularly to reduce contamination. Some adjustments to dental office and the use of barriers are recommended.

Correlation between Stress and Anxiety to Viral Epidemics (SAVE) and Burnout among Korean Dental Hygienists during the COVID-19 Pandemic: A Cross-Sectional Study

This study aimed to investigate the correlations among Stress and Anxiety to Viral Epidemics (SAVE), job stress (JS), and burnout among Korean dental hygienists during the COVID-19 pandemic and to identify the moderating effect of JS. As a cross-sectional study, a self-reporting questionnaire was used to survey 204 clinical dental hygienists to measure the levels of SAVE, JS, and burnout, along with their demographic characteristics as the control variables. Pearson correlation analysis and hierarchical multiple regression analysis were performed to analyse the correlations among burnout, SAVE, and JS, including the moderating effect of JS. With education level and subjective health controlled, JS (β = 1.05, p < 0.001), SAVE (β = 0.69, p = 0.020) and the interaction between SAVE and JS (β = −0.93, p = 0.050) were identified as significant influencing factors of burnout. The adjusted explanatory power of the model was found to be 52.4%. In summary, both SAVE and JS were significant influencing factors of burnout among dental hygienists, while a moderating effect of JS was also identified. Therefore, it is necessary to create a work environment that can relieve SAVE and JS to reduce burnout among dental hygienists.

Real-time Monitoring of Aerosol Generating Dental Procedures

OBJECTIVE

We aimed to quantify aerosol concentrations produced during different dental procedures under different mitigation processes.

METHOD

Aerosol concentrations were measured by the Optical Particle Sensor (OPS) and Wideband Integrated Bioaerosol Sensor (WIBS) during routine, time-recorded dental procedures on a manikin head in a partitioned enclosure. Four different, standardised dental procedures were repeated in triplicate for three different mitigation measures.

RESULT

Both high-volume evacuation (HVE) and HVE plus extra-oral suction (LEV) eradicated all procedure-related aerosols, and the enclosure stopped procedure-related aerosols escaping. Aerosols recorded by the OPS and WIBS were 84 and 16-fold higher than background levels during tooth 16 FDI notation (UR6) drilling, and 11 and 24-fold higher during tooth 46 FDI notation (LR6) drilling, respectively. Ultrasonic scaling around the full lower arch (CL) or the full upper arch (CU) did not generate detectable aerosols with mitigation applied. Without mitigation the largest concentration of inhalable particles during procedures observed by the WIBS and OPS was during LR6 (139/cm³) and UR6 (28/cm³) drilling, respectively. Brief aerosol bursts were recorded during drilling procedures with HVE, these did not occur with LEV, suggesting LEV provides protection against operator errors. Variation was observed in necessary fallow times (49 - 280 minutes) without mitigation, while no particles remained airborne when mitigation was utilised.

CONCLUSION

This data demonstrates that correctly positioned HVE or LEV is effective in preventing airborne spread and persistence of inhalable particles originating from dental AGPs. Additionally, a simple enclosure restricts the spread of aerosols outside of the operating area.

CLINICAL SIGNIFICANCE

Employing correctly positioned HVE and LEV in non-mechanically ventilated clinics can prevent the dispersal and persistence of inhalable airborne particles during dental AGPs. Moreover, using enclosures have the additive effect of restricting aerosol spread outside of an operating area.

Efficacy of Aerosol Reduction Measures for Dental Aerosol Generating Procedures

Aerosol particles generated by dental procedures could facilitate the transmission of infectious diseases and contain carcinogen particles. Such particles can penetrate common surgical masks and reach the lungs, leading to increased risk for dental care professionals. However, the risk of inhaling contaminated aerosol and the effectiveness of aerosol reduction measures in dental offices remain unclear. The present study aimed to quantify aerosols produced by drilling and scaling procedures and to evaluate present recommendations for aerosol reduction. The concentration of aerosol particles released from the mock scaling and drilling procedures on dental mannequin were measured using a TSI Optical Particle Sizer (OPS 3330) during 15-min sessions carried out in a single-patient examination room. Using a drilling procedure as the aerosol source, the aerosol reduction performance of two types of high-volume evacuators (HVEs) and a commercial off-the-shelf air purifier was evaluated in a simulated clinical setting. Using either HVEs or the air purifier individually reduced the aerosol accumulated over the course of a 15-minutes drilling procedure at a reduction rate of 94.8 to 97.6%. Using both measures simultaneously raised the reduction rate to 99.6%. The results show that existing HVEs can effectively reduce aerosol concentration generated by a drilling procedure and can be further improved by using an air purifier. Following current regulatory guidelines can ensure a low risk of inhaling contaminated aerosol for dentists, assistants, and patients.

Knowledge About Biosafety Measures in Clinical Setting During the COVID-19 Pandemic: A Cross-Sectional Study With Brazilian Dental Students

OBJECTIVE

The aim of this study is to evaluate the knowledge of Brazilian dental students about biosafety measures that should be adopted in the clinical setting during the coronavirus disease (COVID-19) pandemic.

METHODS

A cross-sectional study with 1050 dental students was conducted. A semi-structured questionnaire was shared with students. Mean knowledge score on biosafety guidelines during the COVID-19 pandemic was the outcome, with a maximum of 8 scores. Explanatory variables included sociodemographic and educational characteristics, aspects related to biosafety education, actions adopted by the dental schools during the pandemic, and sources of biosafety information. Multivariate linear regression analyses were performed.

RESULTS

Mean knowledge score was 5.19 (1.28). Female students (β = 0.346; 95% CI: 0.154-0.539), those enrolled in the intermediate (β = 0.525; 95% CI: 0.167-0.883) or final (β = 0.569; 95% CI: 0.200-0.937) stage of course, and those who had already received theoretical-practical training in biosafety (β = 0.464; 95% CI: 0.063-0.866) presented higher mean knowledge scores. Students who did not receive guidance on aerosol control measures before the pandemic (β = -0.324; 95% CI: -0.519 to -0.130) had the lowest score.

CONCLUSION

Students presented a medium level of knowledge about dental biosafety measures concerning the COVID-19 pandemic. Sociodemographic characteristics and those related to the institutional profile of the participants, and access to orientation and training in biosafety, may influence their knowledge.

Infection Risk Prediction Model for COVID-19 Based on an Analysis of the Settlement of Particles Generated during Dental Procedures in Dental Clinics

Background

The health emergency declaration owing to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has drawn attention toward nosocomial transmission. The transmission of the disease varies depending on the environmental conditions. Saliva is a recognized SARS-CoV-2 reservoir in infected individuals. Therefore, exposure to fluids during dental procedures leads to a high risk of contagion.

Objective

This study aimed to develop an infection risk prediction model for COVID-19 based on an analysis of the settlement of the aerosolized particles generated during dental procedures.

Materials and Methods

The settlement of aerosolized particles during dental aerosol-generating procedures (AGPs) performed on phantoms was evaluated using colored saliva. The gravity-deposited particles were registered using a filter paper within the perimeter of the phantom head, and the settled particles were recorded in standardized photographs. Digital images were processed to analyze the stained area. A logistic regression model was built with the variables ventilation, distance from the mouth, instrument used, area of the mouth treated, and location within the perimeter area.

Results

The largest percentage of the areas stained by settled particles ranged from 1 to 5 µm. The maximum settlement range from the mouth of the phantom head was 320 cm, with a high-risk cutoff distance of 78 cm. Ventilation, distance, instrument used, area of the mouth being treated, and location within the perimeter showed association with the amount of settled particles. These variables were used for constructing a scale to determine the risk of exposure to settled particles in dentistry within an infection risk prediction model.

Conclusion

The greatest risk of particle settlement occurs at a distance up to 78 cm from the phantom mouth, with inadequate ventilation, and when working with a high-speed handpiece. The majority of the settled particles generated during the AGPs presented stained areas ranging from 1 to 5 µm. This model was useful for predicting the risk of exposure to COVID-19 in dental practice.

Computational Fluid Dynamics Optimization of an Extraoral Vacuum Aerosol Cup for Airborne Disease Control in Dental Offices

Droplet and aerosol transmission of COVID-19 are the most important concerns in dental clinics, due to the generation of large amounts of infected aerosol and droplets mixed with patient’s saliva during the procedures. The current approach to prevent airborne disease transmission is an extraoral aerosol suction unit: a stand-alone vacuum module with a segmented arm and cup. Despite the need for disease control in dental offices, these units are rarely seen due to the loud noise produced by vacuum, bulky size, and high cost. This paper describes the aerodynamic design optimization of an affordable, 3D printable, Extraoral Vacuum Aerosol Cup (EVAC) that can be directly connected to existing standard 7/16″ central vacuum high-volume evacuator (HVE) valves used for intraoral saliva absorption in a dental office. These HVEs are typically unsuitable for extraoral suction due to their low vacuum force. However, they can be used for extraoral suction, if the cup attachment is aerodynamically optimized for maximum suction efficiency. Fifteen different designs of EVAC are proposed and their suction processes were simulated with computational fluid dynamics. Droplets of various sizes are released to mimic the droplets produced during dental operation. The suction performances of EVACs with different sizes and shapes were compared to find out the designs with optimal performance. Prototypes of the optimized EVAC are 3D printed and tested at a dental office. Development and manufacturing of such a device will largely reduce the COVID-19 infection risk, thus improving the safety protection for both patients and doctors at dental offices.

Application of recommended preventive measures against COVID-19 could help mitigate the risk of SARS-CoV-2 infection during dental practice: Results from a follow-up survey of French dentists

Background

During the first-wave of the COVID-19 pandemic, dentists were considered at high-risk of infection. In France, to stop the spread of SARS-CoV-2, a nationwide lockdown was enforced, during which dentists suspended their routine clinical activities, working solely on dental emergencies. This measure has had an indisputable mitigating effect on the pandemic. To continue protecting dentists after suspension of nationwide lockdown, implementation of preventive measures was recommended, including adequate personal protective equipment (PPE) and room aeration between patients. No study has explored whether implementation of such preventive measures since the end of the first-wave has had an impact on the contamination of dentists.

Methods

An online survey was conducted within a French dentist population between July and September 2020. To explore risk factors associated with COVID-19, univariate and multivariate logistic regression analyses were performed.

Results

The results showed that COVID-19 prevalence among the 3497 respondents was 3.6%. Wearing surgical masks during non-aerosol generating procedures was a risk factor of COVID-19, whereas reducing the number of patients was a protective factor.

Conclusions

Considering the similar COVID-19 prevalence between dentists and the general population, such data suggest that dentists are not overexposed in their work environment when adequate preventive measures are applied.

Impact

Dentists should wear specific PPE (FFP2, FFP3 or (K)N95 masks) including during non-aerosol generating procedures and reduce the number of patients to allow proper implementation of disinfection and aeration procedures. Considering the similarities between COVID-19 and other viral respiratory infections, such preventive measures may also be of interest to limit emerging variants spread as well as seasonal viral outbreaks.

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.

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.

Removal and dispersal of biofluid films by powered medical devices: Modeling infectious agent spreading in dentistry

Medical procedures can disperse infectious agents and spread disease. Particularly, dental procedures may pose a high risk of disease transmission as they use high-powered instruments operating within the oral cavity that may contain infectious microbiota or viruses. Here we assess the ability of powered dental devices in removing the biofluid films and identified mechanical, hydrodynamic, and aerodynamic forces as the main underlying mechanisms of removal and dispersal processes. Our results indicate that potentially infectious agents can be removed and dispersed immediately after dental instrument engagement with the adherent biofluid film, while the degree of their dispersal is rapidly depleted owing to the removal of the source and dilution by the coolant water. We found that droplets created by high-speed drill interactions typically travel ballistically, while aerosol-laden air tends to flow as a current over surfaces. Our mechanistic investigation offers plausible routes for reducing the spread of infection during invasive medical procedures.

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Mechanical, hydrodynamic, and aerodynamic forces drive removal/dispersal processes

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The air-rotor has the highest ability to remove and disperse infectious agents

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The aerosol cloud flows as a current and continuously settles

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Manipulating rheological properties of the fluids can suppress aerosol generation

Local Exhaust Ventilation to Control Dental Aerosols and Droplets

Dental procedures produce aerosols that may remain suspended and travel significant distances from the source. Dental aerosols and droplets contain oral microbes, and there is potential for infectious disease transmission and major disruption to dental services during infectious disease outbreaks. One method to control hazardous aerosols often used in industry is local exhaust ventilation (LEV). The aim of this study was to investigate the effect of LEV on aerosols and droplets produced during dental procedures. Experiments were conducted on dental mannequins in an 825.4-m³ open-plan clinic and a 49.3-m³ single surgery. Ten-minute crown preparations were performed with an air-turbine handpiece in the open-plan clinic and 10-min full-mouth ultrasonic scaling in the single surgery. Fluorescein was added to instrument irrigation reservoirs as a tracer. In both settings, optical particle counters (OPCs) were used to measure aerosol particles between 0.3 and 10.0 µm, and liquid cyclone air samplers were used to capture aerosolized fluorescein tracer. In addition, in the open-plan setting, fluorescein tracer was captured by passive settling onto filter papers in the environment. Tracer was quantified fluorometrically. An LEV device with high-efficiency particulate air filtration and a flow rate of 5,000 L/min was used. LEV reduced aerosol production from the air-turbine handpiece by 90% within 0.5 m, and this was 99% for the ultrasonic scaler. OPC particle counts were substantially reduced for both procedures and air-turbine settled droplet detection reduced by 95% within 0.5 m. The effect of LEV was substantially greater than suction alone for the air-turbine and was similar to the effect of suction for the ultrasonic scaler. LEV reduces aerosol and droplet contamination from dental procedures by at least 90% in the breathing zone of the operator, and it is therefore a valuable tool to reduce the dispersion of dental aerosols.

Dental Emergencies: Perceived impact of the COVID-19 pandemic on the mental health and wellbeing of dental teams in the UK

The burden of the COVID-19 pandemic has and continues to stretch the healthcare systems and the workforce alike, both nationally and internationally. This is equally true of the dental care systems and the dental workforce which had to respond and act promptly.This paper examines the perceived impact of the COVID-19 pandemic on the mental health and wellbeing of dental teams in the UK and provides insight into not only this impact, but the early signs of mental ill health commonly triggered by life events, anxiety and fear, and often exacerbated by stresses. A sample of an established body of literature and recognised sources are considered. Finally, extracts of common threads from meaningful conversations will be alluded to, shining a light on the current state of the mental health and wellbeing of many in dentistry and the need for intervention and longer-term plans. We are often reminded that this period in time is a marathon not a sprint, the same could perhaps be said about a national response to mental health and wellbeing, as it will take time, but the time to begin is now.

Restoration of dental services after COVID-19: The fallow time determination with laser light scattering

In time, dental health care has slowly expanded beyond emergency treatment to treat oral diseases. How to reduce the cross-transmission risk in dental surgery has raised much more attention. Considering the lack of consistency of fallow time (FT) in its necessity and duration, the highly sensitive laser light scattering method has been proposed to visualize the airborne lifetime and decay rate of suspended particles in the dental surgery environment. The FT is defined as when the number of suspended particles drops to the level that the next patient can safely enter after the aerosol-generating procedures (AGPs). The ultrasonic scaling was performed in the mock-up experimental dental clinic with 6 air changes per hour (ACH), and the instantaneous moments of the droplets were recorded by a high-speed camera. Without any mitigation measures, the estimated FT in the single dental surgery environment with 6 ACH was in the range of 27-35 min, significantly affecting the number of daily dental services. Despite the cooperation of high-volume evacuation (HVE [IO]) cannot eliminate the FT to zero minutes, the equipment could reduce the required FT by 3-11 min for the suspended particles reducing the baseline levels. Owing to the longer airborne lifetime of suspended particles, the relevant protection equipment, especially respiratory protection, is quite essential in dental surgery. The obtained results of this study will provide evidence to establish the revised FT in dental surgery guidelines and protect the health and wellbeing of urban dwellers.

How the high-volume evacuation alters the flow-field and particle removal characteristics in the mock-up dental clinic

The exposure risk of droplets and aerosols emitted from the oral cavity to the dental professionals and patients has received more attention especially the ongoing outbreak of COVID-19. The aim of this study is to address the question about how the use of the high-volume evacuation (HVE) alters the risk profiles compared with the situation only personal protective equipment (PPE). The risk profiles of the different situations were analyzed in terms of droplet velocity, flow field characteristics, and particle removal efficiency. The ultrasonic scaling with suction was performed in the mock-up experimental dental clinic, and the instantaneous moment when the HVE acted on the droplets was visualized using a laser light scattering technique. From the results of the velocity profiles, the hypothesis about the moderate effect of the HVE on high-velocity small droplets near the mannequin's mouth had been firstly proven in this study. The suction can be characterized as low-threshold equipment to bring substantial benefits to reduce the area of the contaminated region. Once the cooperation of suction, the pair of vortexes that were in the face shield area of the dental professional would be eliminated, removing the high-level contaminated region near the breathing area of dental professionals. Compared with the low and medium volume evacuation, the particle removal efficiency of the HVE was more stable at 60%. The research will provide references to the HVE recommendation in the dentistry clinical practice guidelines.

An experimental approach to analyze aerosol and splatter formations due to a dental procedure

Throughout 2020 and beyond, the entire world has observed a continuous increase in the infectious spread of the novel coronavirus (SARS-CoV-2) otherwise known as COVID-19. The high transmission of this airborne virus has raised countless concerns regarding safety measures employed in the working conditions for medical professionals. Specifically, those who perform treatment procedures on patients which intrinsically create mists of fine airborne droplets, i.e., perfect vectors for this and other viruses to spread. The present study focuses on understanding the splatter produced due to a common dentistry technique to remove plaque buildup on teeth. This technique uses a high-speed dentistry instrument, e.g., a Cavitron ultrasonic scaler, to scrape along the surface of a patient's teeth. This detailed understanding of the velocity and the trajectory of the droplets generated by the splatter will aid in the development of hygiene mechanisms to guarantee the safety of those performing these procedures and people in clinics or hospitals. Optical flow tracking velocimetry (OFTV) method was employed to obtain droplet velocity and trajectory in a two-dimensional plane. Multiple data collection planes were taken in different orientations around a model of adult mandibular teeth. This technique provided pseudo-three-dimensional velocity information for the droplets within the splatter developed from this high-speed dental instrument. These results indicated that within the three-dimensional splatter produced there were high velocities (1-2 m/s) observed directly below the intersection point between the front teeth and the scaler. The splatter formed a cone-shape structure that propagated 10-15 mm away from the location of the scaler tip. From the droplet trajectories, it was observed that high velocity isolated droplets propagate away from the bulk of the splatter. It is these droplets which are concerning for health safety to those performing the medical procedures. Using a shadowgraphy technique, we further characterize the individual droplets' size and their individual velocity. We then compare these results to previously published distributions. The obtained data can be used as a first step to further examine flow and transport of droplets in clinics/dental offices.

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.

Aerosol generating procedural risks and concomitant mitigation strategies in orthodontics amid COVID-19 pandemic - An updated evidence-based review

IMPORTANCE

The ongoing COVID-19 pandemic has posed unique challenges to orthodontic profession by adversely impacting provision of in-office orthodontic care due to prevailing uncertainty around risks pertaining to splatter and 'aerosol-generating procedures' (AGPs). This review aims to provide an insight into the prevailing and emerging evidence informing potential risks related to splatter and AGPs, and risk mitigation strategies employed for reducing the potential risk of SARS-CoV-2 transmission from dental bioaerosols.

METHODS

PubMed, Google Scholar, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, LILACS, WHO COVID-19 databases and preprint databases were searched for eligible English language publications. Citation chasing was undertaken up until the review date of 4 January 2021. Study selection, data extraction and risk of bias assessment was undertaken independently in duplicate, or else by consultation with a third author.

RESULTS

Following filter application and duplicates removed, a total of 13 articles assessing procedural mitigation measures were included. Seven included studies revealed overall low-risk of bias. The overall risk varied from unclear to high for rest of the studies, with the most concerning domains being blinding of the participants and the personnel and blinding of the outcome assessors. Accumulated consensual evidence points towards the use of dental suction devices with wide bore aspirating tips as effective procedural mitigation strategies. Variations in the literature can be observed concerning aerosol transmission associated with water spray use during debonding. Emerging direct evidence consistently supports adjunctive use of pre-procedural povidone-iodine mouthrinse to mitigate direct transmission risk in the orthodontic practice.

CONCLUSIONS

A thorough risk assessment concerning AGPs and implementation of consistent and evidence-based procedural mitigation strategies may play an indispensable role in navigating optimal orthodontic practice through unforeseen similar pandemic threats. High-quality robust research focussing on more biologically relevant models of dental bioaerosols in orthodontic settings is warranted.

Endodontic procedures produce bacterial droplet contamination - but what about viruses?

Research question The study aims to investigate spread, distance and spatial distribution of aerosolised microorganisms generated through various endodontic procedures.

Study design A case-control study carried out at the University of Maryland, US in 2020. The study investigated the aerosolised microorganisms produced during three endodontic treatments: emergency pulpotomy, emergency pulpectomy and non-surgical root canal therapy (NSRCT), with 15 participants in each group (n = 45). Patients diagnosed with symptomatic apical periodontitis were included. The use of settle plates for passive air sampling was employed, in a 4 x 4 m room with closed doors. The number of colony-forming units (CFUs) and composition of bacterial species were analysed. Variables within the study included: distance of plate to patient's mouth (0.5 m or 2 m), positioning of plate (directly in front of or diagonal to the participant's mouth), type of endodontic treatment performed and the duration of treatment. A baseline sample was collected (room at rest) as a control. All dental treatment was carried out under rubber dam, after patients had undergone a pre-operative 0.12% chlorhexidine digluconate mouth rinse for 60 seconds. An extraoral suction system (ADS EOS Dental System Inc; Ontario, CA, USA) was also placed directly in front of the patient's mouth throughout treatment.

Results A significantly greater number of CFUs were recorded after endodontic treatments (all treatments), compared to negative control. CFUs were lower in the emergency pulpotomy group compared to the other two groups. There was a significantly lower number of CFUs found at plates situated 0.5 m, compared to 2 m, away from the patient. There was a positive correlation between the procedure duration and CFU count. The main bacterial species detected were Staphylococcus aureus (48.8%), Staphlococcus epidermidis (42.2%) and oral streptococci (33.1%). Pseudomonas aeruginosa and fungi were not detected.

Conclusion Emergency pulpectomy and NSRCT created greater microbial contamination than an emergency pulpotomy. Greater numbers of microorganisms were found after longer treatment times and closer to the patient's mouth.

Dentist Related Factors Associated with Implementation of COVID-19 Protective Measures: A National Survey

Little is known about the extent to which dentists have implemented COVID-19 infection control guidelines and the factors influencing this process in daily practice. This national online survey assessed the implementation of enhanced infection control guidelines in daily practice, and explored dentist related factors influencing their application, more specifically dentist infection status and their perceived risk of cross-infection in the dental setting. The survey was validated, pretested and carried out in 2020. A total of 1436 dentists participated, of whom 9.1% presumably had COVID-19 infection experience. At least 75% of dentists complied with the core part of the recommended protective measures protocol. For each patient treated during the pandemic, an additional cost of 10–30 EUR (86.7%) and an extra time of 10–30 min (70.7%) was estimated. A stepwise binary logistic regression analysis revealed that dentists assumed to have experienced COVID-19 reported a higher self-perceived risk of virus acquisition (β = 2.090; p = 0.011), lower concern of getting infected (β = 0.576; p = 0.027), and lower confidence in being able to prevent disease transmission in the dental setting (β = 0.535; p = 0.022). Some parts of the protective measures were more difficult to apply than others; however, there was no indication of increased disease acquisition in the dental setting.

The COVID-19 pandemic and its global effects on dental practice. An international survey

Objectives

A multicentre survey was designed to evaluate the impact of COVID-19 outbreak on dental practice worldwide, estimate the COVID-19 related symptoms/signs, work attitudes and behaviour and the routine use of protective measures and Personal Protective Equipment (PPE).

Methods

A global survey using a standardized questionnaire with research groups from 36 countries was designed. The questionnaire was developed and pretested during April 2020 and contained three domains: 1) Personal data; 2) COVID-19 positive rate and symptoms/signs presumably related to the coronavirus; 3) Working conditions and PPE adopted after the outbreak. Countries’ data were grouped by the Country Positive Rate (CPR) during the survey period and by Gross-National-Income per capita. An ordinal multinomial logistic regression model was carried out with COVID-19 self-reported rate referred by dental professionals as dependent variable to assess the association with questionnaire items.

Results

A total of 52,491 questionnaires were returned with a male/female ratio of 0.63. Out of the total respondents, 7,859 dental professionals (15%) reported symptoms/signs compatible with COVID-19. More than half of the sample (n = 27,818; 53%) stated to use FFP2/N95 masks, while 21,558 (41.07%) used eye protection. In the bivariate analysis, CPR and N95/FFP2 were significantly associated (OR = 1.80 _95%CI = 1.60/2.82 and OR = 5.20 _95%CI = 1.44/18.80, respectively), while Gross-National-Income was not statistically associated with CPR (OR = 1.09 _95%CI = 0.97/1.60). The same significant associations were observed in the multivariate analysis.

Conclusions

Oral health service provision has not been significantly affected by COVID-19, although access to routine dental care was reduced due to country-specific temporary lockdown periods. While the dental profession has been identified at high-risk, the reported rates of COVID-19 for dental professionals were not significantly different to those reported for the general population in each country. These findings may help to better plan oral health care for future pandemic events.

The effect of high-speed dental handpiece coolant delivery and design on aerosol and droplet production

OBJECTIVES

High-speed dental instruments produce aerosol and droplets. The objective of this study was to evaluate aerosol and droplet production from a novel electric micromotor handpiece (without compressed air coolant) in real world clinical settings.

METHODS

10-minute upper incisor crown preparations were performed in triplicate in an open-plan clinic with mechanical ventilation providing 3.45 air changes per hour. A 1:5 ratio electric micromotor handpiece which allows water coolant without compressed air (Ti-Max Z95L, NSK) was used at three speeds: 60,000 (60 K), 120,000 (120 K), and 200,000 (200 K) revolutions per minute. Coolant solutions contained fluorescein sodium as a tracer (2.65 mmol L ^- 1). High-speed air-turbine positive control, and negative control conditions were conducted. Aerosol production was evaluated at 3 locations (0.5 m, 1.5 m, and 1.7 m) using: (1) an optical particle counter (OPC; 3016-IAQ, Lighthouse) to detect all aerosol; and (2) a liquid cyclone air sampler (BioSampler, SKC Ltd.) to detect aerosolised fluorescein, which was quantified by spectrofluorometric analysis. Settled droplets were detected by spectrofluorometric analysis of filter papers placed onto a rig across the open-plan clinic.

RESULTS

Local (within treatment bay) settled droplet contamination was elevated above negative control for all conditions, with no difference between conditions. Settled droplet contamination was not detected above negative controls outside the treatment bay for any condition. Aerosol detection at 1.5 m and 1.7 m, was only increased for the air-turbine positive control condition. At 0.5 m, aerosol levels were highly elevated for the air-turbine, minimally elevated for 200 K and 120 K, and not elevated for 60 K.

CONCLUSIONS

Electric micromotor handpieces which use water-jet coolant alone without compressed air produce localised (within treatment bay) droplet contamination, but are unlikely to produce aerosol contamination beyond the immediate treatment area (1.5 m), allowing them to be used safely in most open-plan clinic settings.

Effects of Natural Ventilation and Saliva Standard Ejectors during the COVID-19 Pandemic: A Quantitative Analysis of Aerosol Produced during Dental Procedures

The novel Coronavirus Disease 2019 (COVID-19) pandemic has renewed attention to aerosol-generating procedures (AGPs). Dental-care workers are at high risk of contamination by SARS-CoV-2. The aim of this study was to evaluate the efficacy of standard saliva ejectors and natural ventilation in reducing particulate matter (PM) concentration during different routine dental procedures in the pandemic period. The DustTrak monitor was used to measure PM1, PM2.5, PM10, and breathable (<4 microns) total dust during 14 procedures performed with and without the presence of natural ventilation in a dental unit. Moreover, measurements were performed near the practitioners or near the standard saliva ejectors during the different procedures. In the latter condition, reduced levels of PM10 were recorded (82.40 ± 9.65 μg/m³ vs. 50.52 ± 0.23 μg/m³). Moreover, higher levels of PM (53.95 ± 2.29 μg/m³ vs. 27.85 ± 0.14 μg/m³) were produced when the dental unit's windows were open. At the same time, the total level of PM were higher during scaling than during other procedures (data suggest not to adopt natural ventilation-both window and door opened-during dental procedures). It was also demonstrated that the use of standard saliva ejectors can considerably reduce the total released amount of PM10.

Management of systemic risk factors ahead of dental implant therapy: A beard well lathered is half shaved

As the most successful therapy for missing teeth, dental implant has become increasingly prevalent around the world. A lot of papers have reported diverse local risk factors affecting the success and survival rate of dental implants, either for a short or a long period. However, there are also many types of systemic disorders or relatively administrated medicine that may jeopardize the security and success of dental implant treatment. Additionally, the coronavirus disease 2019 pandemic also poses a challenge to dental implant clinicians. Some of these risk factors are clinically common but to some extent unfamiliar to dentists, thus optimal measurements are often lacking when they occur in dental clinics. In this review, we analyze potential systemic risk factors that may affect the success rate of dental implants. Some of them may affect bone mineral density or enhance the likelihood of local infection, thus impeding osseointegration. Others may even systemically increase the risk of the surgery and threaten patients' life. In order to help novices receive high-risk patients who need to get dental implant treatment in a more reasonable way, we accordingly review recent research results and clinical experiments to discuss promising precautions, such as stopping drugs that impact bone mineral density or the operation, and addressing any perturbations on vital signs.

Dental Education during the COVID-19 Pandemic in a German Dental Hospital

Due to the SARS-CoV-2 pandemic, dental treatment performed by undergraduate students at the University of Marburg/Germany was immediately stopped in spring 2020 and stepwise reinstalled under a new hygiene concept until full recovery in winter 2020/21. Patient treatment in the student courses was evaluated based on three aspects: (1) Testing of patients with a SARS-CoV-2 Rapid Antigen (SCRA) Test applied by student assistants (SA); (2) Improved hygiene regimen, with separated treatment units, cross-ventilation, pre-operative mouth rinse and rubber dam application wherever possible; (3) Recruitment of patients: 735 patients were pre-registered for the two courses; 384 patients were treated and a total of 699 tests with the SCRA test were performed by SAs. While half of the patients treated in the course were healthy, over 40% of the patients that were pre-registered but not treated in the course revealed a disease being relevant to COVID (p < 0.001). 46 patients had concerns to visit the dental hospital due to the increase of COVID incidence levels, 14 persons refused to be tested. The presented concept was suitable to enable patient treatment in the student course during the SARS-CoV-2 pandemic.