The effectiveness of an aerosol reduction device for ultrasonic scalers

Visualisation of Droplet Flow Induced by Ultrasonic Dental Cleaning

INTRODUCTION

During dental treatment procedures ultrasonic scalers generate droplets containing microorganisms such as bacteria and viruses. Hence, it is necessary to study the dynamic properties of generated droplets in order to investigate the risks associated with the spread of infection. The aim of this study was to visualise the flow state of droplets and to evaluate the impact of droplets generated during the use of an ultrasonic scaler during an oral surgical procedure.

METHODS

We studied the spatial flow of liquid droplets through a combination of imaging and numeric simulation of a simulated dental treatment processes. First, we photographed the real time images of the ultrasonic scaler and evaluated the images using image-processing software Image J to visualise the flow of liquid droplets. Finally we simulated the flow process of liquid droplets by using the initial velocity of droplet splashing and the angle of the obtained information using computerised fluid dynamics technology.

RESULTS

Under different working conditions, the droplet particle splashing velocity, maximum height, and spray angle varied, but the particle trajectory was generally parabolic. The maximum droplet velocity varied between 3.56 and 8.56 m/s, and the splashing height was between 40 and 110 mm.

CONCLUSIONS

During risk assessment of an ultrasonic scaler usage, difficulties arise due to the insufficient research on droplet velocity and distribution. This study aims to address this gap by visualising the flow trajectories of droplets generated by ultrasonic scalers. The obtained data will assist in developing more effective interventions based on spatial and temporal distribution of droplets. This provides a new approach for droplet particle research and offers new strategies for public health prevention and control.

What influences the close contact between health care workers and patients? An observational study in a hospital dental outpatient department

BACKGROUND

Dental outpatient departments, characterized by close proximity and unmasked patients, present a considerable risk of respiratory infections for health care workers (HCWs). However, the lack of comprehensive data on close contact (<1.5m) between HCWs and patients poses a significant obstacle to the development of targeted control strategies.

METHODS

An observation study was conducted at a hospital in Shenzhen, China, utilizing depth cameras with machine learning to capture close-contact behaviors of patients with HCWs. Additionally, questionnaires were administered to collect patient demographics.

RESULTS

The study included 200 patients, 10 dental practitioners, and 10 nurses. Patients had significantly higher close-contact rates with dental practitioners (97.5%) compared with nurses (72.8%, P < .001). The reason for the visit significantly influenced patient-practitioner (P = .018) and patient-nurse (P = .007) close-contact time, with the highest values observed in prosthodontics and orthodontics patients. Furthermore, patient age also significantly impacted the close-contact rate with nurses (P = .024), with the highest rate observed in patients below 14 years old at 85% [interquartile range: 70-93].

CONCLUSIONS

Dental outpatient departments exhibit high HCW-patient close-contact rates, influenced by visit purpose and patient age. Enhanced infection control measures are warranted, particularly for prosthodontics and orthodontics patients or those below 14 years old.

Concern about the risk of aerosol contamination from ultrasonic scaler: a systematic review and meta-analysis

BACKGROUND

Many instruments used in dentistry are rotary, such as handpieces, water syringes, and ultrasonic scalers that produce aerosols. The spray created by these instruments can carry, in addition to water, droplets of saliva, blood, and microorganisms, which can pose a risk of infections for healthcare professionals and patients. Due to the COVID-19 pandemic, this gained attention.

OBJECTIVE

The aim was to carry out a systematic review of the evidence of the scope of the aerosol produced by ultrasonic scaler in environmental contamination and the influence of the use of intraoral suction reduction devices.

DESIGN

Scientific literature was searched until June 19, 2021 in 6 databases: Pubmed, EMBASE, Web of science, Scopus, Virtual Health Library and Cochrane Library, without restrictions on language or publication date. Studies that evaluated the range of the aerosol produced by ultrasonic scaler during scaling/prophylaxis and the control of environmental contamination generated by it with the use of low (LVE) and high (HVE) volume evacuation systems were included.

RESULTS

Of the 1893 potentially relevant articles, 5 of which were randomized controlled trials (RCTs). The meta-analysis of 3 RCTs showed that, even at different distances from the patient's oral cavity, there was a significant increase in airborne bacteria in the dental environment with the use of ultrasonic scaler. In contrast, when meta-analysis compared the use of HVE with LVE, there was no significant difference (P = 0.40/CI -0.71[-2.37, 0.95]) for aerosol produced in the environment.

CONCLUSIONS

There is an increase in the concentration of bioaerosol in the dental environment during the use of ultrasonic scaler in scaling/prophylaxis, reaching up to 2 m away from the patient's mouth and the use of LVE, HVE or a combination of different devices, can be effective in reducing air contamination in the dental environment, with no important difference between different types of suction devices.

Effectiveness of interventions to reduce aerosol generation in dental environments: A systematic review

Certain dental procedures produce high levels of aerosols containing pathogenic microorganisms, posing a risk for the transmission of infections in dental settings. This study aimed to assess the effectiveness of various aerosol mitigation interventions during clinical dental procedures in real-world environments. A systematic literature search was conducted in PubMed/MEDLINE, Scopus, Web of Science, and Embase for English studies up to March 2023 according to the PRISMA guidelines. Only peer-reviewed controlled clinical trials (CCT) or randomized controlled trials (RCT) studies involving human subjects were included. The risk of bias of selected researches were evaluated by two independent authors using the Cochrane Collaboration tool. The literature search yielded 3491 articles, of which 42 studies met the inclusion criteria and were included in this study. Most studies evaluated bacterial contamination in bio-aerosols, while the viral and fungal contamination was assessed in only three studies. Overall, various approaches have been applied in reducing aerosol contamination in clinical scenarios, including high-volume evacuators (HVE), mouse rinses and rubber dams, air cleaning systems, and high-efficiency particulate air (HEPA) filters. The available evidence suggests that various aerosol mitigation strategies could be implemented to decrease the risk of cross-infection during clinical dental procedures in real-world environments. However, further clinical trials are necessary to establish statistical validity in measuring aerosol contamination and mitigation, as well as to evaluate the risk of infection transmission for viral and fungal contamination.

Efficiency of HEPA-filtered extra-oral suction unit on aerosols during prosthetic dental preparation: A pilot study

OBJECTIVES

Aerosols formed during dental treatments have a huge risk for the spread of bacteria and viruses. This study is aimed at determining which part of the working area and at what size aerosol is formed and ensuring more effective use of HEPA-filtered devices.

MATERIALS AND METHODS

Anterior tooth preparation was performed by one dentist with one patient. Particle measurements were made using an airborne particle counter and were taken at four different locations: the chest of the patient, the chest of the dentist, the center of the room, and near the window. Three groups were determined for this study: group 1: measurement in a 24-h ventilated room (before the tooth preparation, empty room), group 2: measurement with the use of saliva ejector (SE), and group 3: measurement with the use of saliva ejector and HEPA-filtered extra-oral suction (HEOS) unit.

RESULTS

The particles generated during tooth preparation were separated according to their sizes; the concentration in different locations of the room and the efficiency of the HEOS unit were examined.

CONCLUSIONS

The present study showed that as the particle size increases, the rate of spread away from the dentist's working area decreases. The HEPA-filtered extra-oral suction unit is more effective on particles smaller than 0.5 microns. Therefore, infection control methods should be arranged according to these results.

CLINICAL RELEVANCE

The effective and accurate use of HEPA-filtered devices in clinics significantly reduces the spread of bacterial and viral infections and cross-infection.

Modern modified aerosol box: Isolation aid for oral health care professionals during dental procedures

COVID-19 affected healthcare professionals globally, especially dentists, which is airborne and transmitted through contact. Most dental procedures are aerosol generated and these aerosols in dental practice tend to transmit acute respiratory infections like COVID-19. Recently, a few authors recommended using the aerosol box to reduce the aerosol count in a dental setting. However, the study aims to describe and recommend a reformed aerosol box desand to practice safe dentistry.

Aerosol reduction of two dental extraoral scavenger devices in vitro

Objective

Since the outbreak of SARS-CoV-2, aerosol control in the operatory has become a key safety issue in dentistry. The utilisation of extraoral scavenger devices (EOSs) is one of the various approaches to in-treatment aerosol reduction in dentistry. The use and efficacy of EOSs in dental settings, however, are still a matter of debate in the literature and there are still open questions about their proper use. Thus, research into this area is essential to inform dental practice. The objective of this study was to examine the aerosol reduction efficacy of two different EOS in vitro.

Methods

Two commercially available EOSs were tested during modeled dental treatment in a setup that previously proved to generate high aerosol load. Measurements were done in two particle size ranges: 5.6–560 nm (the full range of the spectrometer) and 60.4–392.4 nm (a range that is especially relevant to the spread of SARS-CoV-2 with aerosol).

Results

Both devices managed to reduce the aerosol load to a statistically significant extent as compared to the scenario when only a high-volume evacuator and a saliva ejector (and no EOS) were used.

Conclusions

Within the limitations of the study, the results support the assumption that EOSs for aerosol reduction increase in-treatment safety in the dental operatory.

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.

Experimental evaluation of aerosol mitigation strategies in large open-plan dental clinics

BACKGROUND

Aerosols are generated routinely during patient care in dentistry. Managing exposure risk requires understanding characteristics of aerosols created during procedures such as those performed using high-speed drills that operate at 200,000 revolutions per minute.

METHODS

A trained dentist performed drilling procedures on a manikin's incisors (teeth nos. 8 and 9) using a high-speed drill and high-volume evacuator. The authors used high-speed imaging to visualize the formation and transport of aerosol clouds and particle sampling to measure aerosol concentration and size distribution at several locations. The authors studied several aerosol mitigation strategies.

RESULTS

Aerosols produced during high-speed drilling were erratic and yielded high concentrations that were at least an order of magnitude above baseline. High-speed imaging showed aerosols initially travelled at 1 m per second. Owing to erratic behavior of aerosols, supplemental suction was not effective at collecting all aerosols; however, barriers were effective.

CONCLUSIONS

Barriers are the most effective mitigation strategy. Other methods studied have limitations and risks. To the authors' knowledge, this article presents the first characterization of aerosols generated during high-speed drilling by a dentist.

PRACTICAL IMPLICATIONS

With thorough preoperative planning and the use of this investigation's findings about effectiveness of mitigation strategies as a guide, dental offices may be able to return to prepandemic productivity.

Virus transmission by ultrasonic scaler and its prevention by antiviral agent: an in vitro study

Background

It is well recognized that dental procedures represent a potential way of infection transmission. With the COVID‐19 pandemic, the focus of dental procedure associated transmission has rapidly changed from bacteria to viruses. The aim was to develop an experimental setup for testing the spread of viruses by ultrasonic scaler (USS) generated dental spray and evaluate its mitigation by antiviral coolants.

Methods

In a virus transmission tunnel, the dental spray was generated by USS with saline coolant and suspension of Equine Arteritis Virus (EAV) delivered to the USS tip. Virus transmission by settled droplets was evaluated with adherent RK13 cell lines culture monolayer. The suspended droplets were collected by a cyclone aero‐sampler. Antiviral activity of 0.25% NaOCl and electrolyzed oxidizing water (EOW) was tested using a suspension test. Antiviral agents' transmission prevention ability was evaluated by using them as a coolant.

Results

In the suspension test with 0.25% NaOCl or EOW, the TCID50/mL was below the detection limit after 5 seconds. With saline coolant, the EAV‐induced cytopathic effect on RK13 cells was found up to the distance of 45 cm, with the number of infected cells decreasing with distance. By aero‐sampler, viral particles were detected in concentration ≤4.2 TCID50/mL. With both antiviral agents used as coolants, no EAV‐associated RK‐13 cell infection was found.

Conclusion

We managed to predictably demonstrate EAV spread by droplets because of USS action. More importantly, we managed to mitigate the spread by a simple substitution of the USS coolant with NaOCl or EOW.

Sources of SARS-CoV-2 and Other Microorganisms in Dental Aerosols

On March 16, 2020, 198,000 dentists in the United States closed their doors to patients, fueled by concerns that aerosols generated during dental procedures are potential vehicles for transmission of respiratory pathogens through saliva. Our knowledge of these aerosol constituents is sparse and gleaned from case reports and poorly controlled studies. Therefore, we tracked the origins of microbiota in aerosols generated during ultrasonic scaling, implant osteotomy, and restorative procedures by combining reverse transcriptase quantitative polymerase chain reaction (to identify and quantify SARS-CoV-2) and 16S sequencing (to characterize the entire microbiome) with fine-scale enumeration and source tracking. Linear discriminant analysis of Bray-Curtis dissimilarity distances revealed significant class separation between the salivary microbiome and aerosol microbiota deposited on the operator, patient, assistant, or the environment (P < 0.01, analysis of similarities). We also discovered that 78% of the microbiota in condensate could be traced to the dental irrigant, while saliva contributed to a median of 0% of aerosol microbiota. We also identified low copy numbers of SARS-CoV-2 virus in the saliva of several asymptomatic patients but none in aerosols generated from these patients. Together, the bacterial and viral data encourage us to conclude that when infection control measures are used, such as preoperative mouth rinses and intraoral high-volume evacuation, dental treatment is not a factor in increasing the risk for transmission of SARS-CoV-2 in asymptomatic patients and that standard infection control practices are sufficiently capable of protecting personnel and patients from exposure to potential pathogens. This information is of immediate urgency, not only for safe resumption of dental treatment during the ongoing COVID-19 pandemic, but also to inform evidence-based selection of personal protection equipment and infection control practices at a time when resources are stretched and personal protection equipment needs to be prioritized.

A clinical investigation of dental evacuation systems in reducing aerosols

Background

The route of transmission of severe acute respiratory syndrome coronavirus 2 has challenged dentistry to improve the safety for patients and the dental team during various treatment procedures. The purpose of this study was to evaluate and compare the effectiveness of dental evacuation systems in reducing aerosols during oral prophylactic procedures in a large clinical setting.

Methods

This was a single-center, controlled clinical trial using a split-mouth design. A total of 93 student participants were recruited according to the inclusion and exclusion criteria. Aerosol samples were collected on blood agar plates that were placed around the clinic at 4 treatment periods: baseline, high-volume evacuation (HVE), combination (HVE and intraoral suction device), and posttreatment. Student operators were randomized to perform oral prophylaxis using ultrasonic scalers on 1 side of the mouth, using only HVE suction for the HVE treatment period and then with the addition of an intraoral suction device for the combination treatment period. Agar plates were collected after each period and incubated at 37 °C for 48 hours. Colony-forming unit (CFU) counts were determined using an automatic colony counter.

Results

The use of a combination of devices resulted in significant reductions in CFUs compared with the use of the intraoral suction device alone (P < .001). The highest amounts of CFUs were found in the operating zone and on patients during both HVE and combination treatment periods.

Conclusions

Within limitations of this study, the authors found significant reductions in the amount of microbial aerosols when both HVE and an intraoral suction device were used.

Practical Implications

The combination of HVE and intraoral suction devices significantly decreases microbial aerosols during oral prophylaxis procedures.

Dental periodontal procedures: a systematic review of contamination (splatter, droplets and aerosol) in relation to COVID-19

INTRODUCTION

The emergence of the SARS-CoV-2 virus and subsequent COVID-19 pandemic has had a significant effect on the delivery of routine dentistry; and in particular, periodontal care across the world. This systematic review examines the literature relating to splatter, droplet settle and aerosol for periodontal procedures and forms part of a wider body of research to understand the risk of contamination in relation to periodontal care procedures relevant to COVID-19.

METHODS

A search of the literature was carried out using key terms and MeSH words relating to the review questions. Sources included Medline (OVID), Embase (OVID), Cochrane Central Register of Controlled Trials, Scopus, Web of Science and LILACS, ClinicalTrials.Gov . Studies meeting inclusion criteria were screened in duplicate and data extraction was carried out using a template. All studies were assessed for methodological quality and sensitivity. Narrative synthesis was undertaken.

RESULTS

Fifty studies were included in the review with procedures including ultrasonic scaling (n = 44), air polishing (n = 4), prophylaxis (n = 2) and hand scaling (n = 3). Outcomes included bacterial (colony-forming units e.g. on settle plates) or blood contamination (e.g. visible splatter) and non bacterial, non blood (e.g. chemiluminescence or coloured dyes) contamination. All studies found contamination at all sites although the contamination associated with hand scaling was very low. Contamination was identified in all of the studies even where suction was used at baseline. Higher power settings created greater contamination. Distribution of contamination varied in relation to operator position and was found on the operator, patient and assistant with higher levels around the head of the operator and the mouth and chest of the patient. Settle was identified 30 min after treatments had finished but returned to background levels when measured at or after an hour. The evidence was generally low to medium quality and likely to underestimate contamination.

CONCLUSION

Ultrasonic scaling, air polishing and prophylaxis procedures produce contamination (splatter, droplets and aerosol) in the presence of suction, with a small amount of evidence showing droplets taking between 30 min and 1 h to settle. Consideration should be given to infection control, areas of cleaning particularly around the patient and appropriate personal protective equipment, with particular attention to respiratory, facial and body protection for these procedures. In addition, the use of lower power settings should be considered to reduce the amount and spread of contamination.

Aerosol and spatter mitigation in dentistry: Analysis of the effectiveness of 13 setups

OBJECTIVES

The current study aims to investigate the aerosol and spatter mitigation quality of 13 dry-field isolation methods in a simulated setup that replicates real-life work scenarios encountered in dental practices.

METHODS

A crown preparation on a manikin was performed on tooth number 30 and repeated five times for each setup to simulate a patient under care. Aerosol, environmental, and operator face shield spatter, and sound intensity was measured. Generalized linear mixed models were used, and posthoc pairwise comparisons were performed to compare least-squares means when appropriate using a Tukey adjustment.

RESULTS

All tested setups showed some environmental spatter formation; however, these were able to control most (and in some cases all) spatter on the operator face shield. All methods resulted in excellent aerosol mitigation when a second line of high-volume evacuation (HVE) was added to the device setup. However, in most setups, total sound levels exceeded 85 dB, posing a concern for prolonged noise exposure.

CONCLUSIONS

The Prototype device and four other tested setups with secondary HVE addition completely eliminated aerosol creation as tested. Spatter of the Face Shield was best eliminated using the Prototype device.

CLINICAL SIGNIFICANCE

Within the limitations of this study, it can be concluded that the dental community has at its disposal equipment that can effectively mitigate aerosol and spatter.

Methods to mitigate infection spread from aerosol-generating dental procedures

Infection control measures play a critical role in preventing the spread of disease in healthcare settings. Concerns that SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), the virus that causes Coronavirus Disease 2019, may be transmitted through droplets and aerosols from both symptomatic and asymptomatic individuals has turned the spotlight on healthcare interventions that involve aerosol generation in the oral cavity, such as many dental and periodontal procedures. This commentary seeks to familiarize the dental practitioner with various infection control methods that may be implemented to mitigate spread of infection in dental settings through aerosol-generating dental procedures.

The efficacy of bio-aerosol reducing procedures used in dentistry: a systematic review

BACKGROUND AND OBJECTIVE

Bio-aerosols, are routinely generated and airborne in clinical dentistry due to the operative instrumentation within an oral environment bathed in salivary organisms. SARS-CoV-2 transmission being responsible for the current pandemic, appears through airborne aerosols and droplets, thus, there has been an intense focus on such aerosol-generating procedures, and their reduction. Hence the objective of this systematic review was to evaluate available data on three major measures: rubber dam application, pre-procedural oral rinse, and high-volume evacuators (HVE) aimed at reducing bio-aerosols.

METHOD

PubMed via Ovid MEDLINE, EBSCO host, Cochrane Library and Web of Science databases were searched between 01 January 1985 and 30 April 2020.

RESULTS

A total of 156 records in English literature were identified, and 17 clinical studies with 724 patients included in the final analysis. Eligible articles revealed the inadequacy of three principle approaches used in contemporary dental practice to minimize such bio-aerosols, rubber dam application, pre-procedural oral rinses, and HVE. The latter is an extremely effective method to reduce bio-aerosols in dentistry, although no single method can provide blanket cover.

CONCLUSION

Present systematic review indicates that employing combination strategies of rubber dam, with a pre-procedural antimicrobial oral rinse, and HVE may contain bio-aerosols during operative procedures.

A clinical study measuring dental aerosols with and without a high-volume extraction device

Introduction External high-volume extraction (HVE) devices may offer a way to reduce any aerosol particulate generated.Aims The aim of this study was to measure the particle count during dental aerosol generating procedures and compare the results with when a HVE device is used.Design A comparative clinical study measuring the amount of PM1, PM2.5 and PM10 aerosol particulate with and without the use of an external HVE device was undertaken.Materials and methods In total, ten restorative procedures were monitored with an industrial Trotec PC220 particle counter. The intervention was an external HVE device.Main outcome methods The air sampler was placed at the average working distance of the clinicians involved in the study - 420 mm.Results In the present study, aerosol particulate was recorded at statistically significantly increased levels during dental procedures without an external HVE deviceversus with the device.Discussion The null hypothesis was rejected, in that significant differences were found between the results of the amount of aerosol particle count with and without a HVE device.Conclusion If the results of the present study are repeated in an in vivo setting, an external high-volume suction device may potentially show a lower risk of transmission of viral particulate.

COVID-19: What do we know?

•Evidence regarding the provision of orthodontic care during the COVID-19 pandemic is examined.

Interventions to reduce contaminated aerosols produced during dental procedures for preventing infectious diseases

BACKGROUND

Many dental procedures produce aerosols (droplets, droplet nuclei and splatter) that harbour various pathogenic micro-organisms and may pose a risk for the spread of infections between dentist and patient. The COVID-19 pandemic has led to greater concern about this risk.

OBJECTIVES

To assess the effectiveness of methods used during dental treatment procedures to minimize aerosol production and reduce or neutralize contamination in aerosols.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases on 17 September 2020: Cochrane Oral Health's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (in the Cochrane Library, 2020, Issue 8), MEDLINE Ovid (from 1946); Embase Ovid (from 1980); the WHO COVID-19 Global literature on coronavirus disease; the US National Institutes of Health Trials Registry (ClinicalTrials.gov); and the Cochrane COVID-19 Study Register. We placed no restrictions on the language or date of publication.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) and controlled clinical trials (CCTs) on aerosol-generating procedures (AGPs) performed by dental healthcare providers that evaluated methods to reduce contaminated aerosols in dental clinics (excluding preprocedural mouthrinses). The primary outcomes were incidence of infection in dental staff or patients, and reduction in volume and level of contaminated aerosols in the operative environment. The secondary outcomes were cost, accessibility and feasibility.

DATA COLLECTION AND ANALYSIS

Two review authors screened search results, extracted data from the included studies, assessed the risk of bias in the studies, and judged the certainty of the available evidence. We used mean differences (MDs) and 95% confidence intervals (CIs) as the effect estimate for continuous outcomes, and random-effects meta-analysis to combine data. We assessed heterogeneity.

MAIN RESULTS

We included 16 studies with 425 participants aged 5 to 69 years. Eight studies had high risk of bias; eight had unclear risk of bias. No studies measured infection. All studies measured bacterial contamination using the surrogate outcome of colony-forming units (CFU). Two studies measured contamination per volume of air sampled at different distances from the patient's mouth, and 14 studies sampled particles on agar plates at specific distances from the patient's mouth. The results presented below should be interpreted with caution as the evidence is very low certainty due to heterogeneity, risk of bias, small sample sizes and wide confidence intervals. Moreover, we do not know the 'minimal clinically important difference' in CFU. High-volume evacuator Use of a high-volume evacuator (HVE) may reduce bacterial contamination in aerosols less than one foot (~ 30 cm) from a patient's mouth (MD -47.41, 95% CI -92.76 to -2.06; 3 RCTs, 122 participants (two studies had split-mouth design); very high heterogeneity I² = 95%), but not at longer distances (MD -1.00, -2.56 to 0.56; 1 RCT, 80 participants). One split-mouth RCT (six participants) found that HVE may not be more effective than conventional dental suction (saliva ejector or low-volume evacuator) at 40 cm (MD CFU -2.30, 95% CI -5.32 to 0.72) or 150 cm (MD -2.20, 95% CI -14.01 to 9.61). Dental isolation combination system One RCT (50 participants) found that there may be no difference in CFU between a combination system (Isolite) and a saliva ejector (low-volume evacuator) during AGPs (MD -0.31, 95% CI -0.82 to 0.20) or after AGPs (MD -0.35, -0.99 to 0.29). However, an 'n of 1' design study showed that the combination system may reduce CFU compared with rubber dam plus HVE (MD -125.20, 95% CI -174.02 to -76.38) or HVE (MD -109.30, 95% CI -153.01 to -65.59). Rubber dam One split-mouth RCT (10 participants) receiving dental treatment, found that there may be a reduction in CFU with rubber dam at one-metre (MD -16.20, 95% CI -19.36 to -13.04) and two-metre distance (MD -11.70, 95% CI -15.82 to -7.58). One RCT of 47 dental students found use of rubber dam may make no difference in CFU at the forehead (MD 0.98, 95% CI -0.73 to 2.70) and occipital region of the operator (MD 0.77, 95% CI -0.46 to 2.00). One split-mouth RCT (21 participants) found that rubber dam plus HVE may reduce CFU more than cotton roll plus HVE on the patient's chest (MD -251.00, 95% CI -267.95 to -234.05) and dental unit light (MD -12.70, 95% CI -12.85 to -12.55). Air cleaning systems One split-mouth CCT (two participants) used a local stand-alone air cleaning system (ACS), which may reduce aerosol contamination during cavity preparation (MD -66.70 CFU, 95% CI -120.15 to -13.25 per cubic metre) or ultrasonic scaling (MD -32.40, 95% CI - 51.55 to -13.25). Another CCT (50 participants) found that laminar flow in the dental clinic combined with a HEPA filter may reduce contamination approximately 76 cm from the floor (MD -483.56 CFU, 95% CI -550.02 to -417.10 per cubic feet per minute per patient) and 20 cm to 30 cm from the patient's mouth (MD -319.14 CFU, 95% CI - 385.60 to -252.68). Disinfectants ‒ antimicrobial coolants Two RCTs evaluated use of antimicrobial coolants during ultrasonic scaling. Compared with distilled water, coolant containing chlorhexidine (CHX), cinnamon extract coolant or povidone iodine may reduce CFU: CHX (MD -124.00, 95% CI -135.78 to -112.22; 20 participants), povidone iodine (MD -656.45, 95% CI -672.74 to -640.16; 40 participants), cinnamon (MD -644.55, 95% CI -668.70 to -620.40; 40 participants). CHX coolant may reduce CFU more than povidone iodine (MD -59.30, 95% CI -64.16 to -54.44; 20 participants), but not more than cinnamon extract (MD -11.90, 95% CI -35.88 to 12.08; 40 participants).

AUTHORS' CONCLUSIONS

We found no studies that evaluated disease transmission via aerosols in a dental setting; and no evidence about viral contamination in aerosols. All of the included studies measured bacterial contamination using colony-forming units. There appeared to be some benefit from the interventions evaluated but the available evidence is very low certainty so we are unable to draw reliable conclusions. We did not find any studies on methods such as ventilation, ionization, ozonisation, UV light and fogging. Studies are needed that measure contamination in aerosols, size distribution of aerosols and infection transmission risk for respiratory diseases such as COVID-19 in dental patients and staff.

Reducing the Risk of COVID-19 Transmission in Dental Offices: A Review

The COVID-19 epidemic has become a major public health challenge around the world. According to the World Health Organization (WHO), as of August 2020 there are more than 833,556 dead and over 24,587,513 people infected around the world. This pandemic has adversely affected many professions around the globe, including dentistry. COVID-19, caused by the Corona virus family, is transmitted mainly by direct contact with an infected person or through the spread of aerosol and droplets. Dentistry by nature is considered to be one of the most vulnerable professions with regards to the high risk of transmission between the dentist, dental team, and patients; therefore, a protocol for infection control and the prevention and spreading of the COVID-19 virus in dental settings is urgently needed. This article reviews essential knowledge about this virus and its transmission and recommends preventive methods based on existing scientific research and recommendations to prevent the spread of this virus in dental offices and clinics.

The efficacy of an extraoral scavenging device on reduction of splatter contamination during dental aerosol generating procedures: an exploratory study

Introduction This study was conducted in light of the SARS-CoV-2 pandemic, which brought UK dentistry to a standstill. The market has seen a recent influx of unproven extraoral scavengers (EOSs), which claim to reduce the risk of particulate spread.Aims To investigate the efficacy of a commercially available EOS device on contamination reduction during dental aerosol generating procedures (AGPs). The secondary aim was to investigate differences between open and closed dental operatories.Method Dental procedures were simulated on a dental manikin using citric acid (10%) added to the water lines with universal indicating paper (UIP) placed in strategic locations in the operatory, on the clinician and assistant. Chromatic change related to settling of splatter containing citric acid on the UIP was analysed to calculate percentage intensity of splatter contamination.Results EOSs resulted in 20% reduction in frequency and 75% reduction in mean intensity of contamination of operatory sites. There was a 33% and 76% reduction in mean intensity contamination for clinician and assistant, respectively. Use of rubber dam and four-handed dentistry resulted in further reduction.Discussion This exploratory study demonstrates contamination by splatter in a simulated dental setting. The concern in dentistry regarding aerosol requires further quantitative investigation of smaller particles.Conclusions The routine use of four-handed dentistry and rubber dam should continue where possible to maximise risk mitigation during AGPs. However, on the basis of our findings, the use of an EOS device can further mitigate the magnitude and concentration of splatter.

Interventions to Reduce Aerosolized Microbes in Dental Practice: A Systematic Review with Network Meta-analysis of Randomized Controlled Trials

The aim of this systematic review and network meta-analysis was to identify and rank the effectiveness of different interventions used in dental practice to reduce microbial load in aerosolized compounds. Seven electronic databases were searched to April 6, 2020, for randomized controlled trials (RCTs) or nonrandomized prospective studies in the field. Study selection, data extraction, and risk-of-bias assessment were performed for all included studies, while the outcome of interest pertained to differences in bacterial load quantification through the use of different interventions prior to aerosol-generating procedures in dental practices. Random effects frequentist network meta-analysis was performed, with mean difference (MD) and 95% CI as the effect measure. Confidence in the documented evidence was assessed through the newly fueled CINeMA framework (Confidence in Network Meta-analysis) based on the GRADE approach (Grading of Recommendations, Assessment, Development and Evaluation). Twenty-nine clinical trials were deemed eligible, 21 RCTs and 8 nonrandomized studies, while 11 RCTs contributed to the network meta-analysis, comprising 10 competing interventions. Tempered chlorhexidine (CHX) 0.2% as compared with nonactive control mouth rinse, prior to routine ultrasonic scaling, was most effective toward reduced postprocedural bacterial load with an MD of -0.92 (95% CI, -1.54 to -0.29) in log₁₀ bacterial CFUs (colony-forming units). For CHX 0.2%, an MD of -0.74 (95% CI, -1.07 to -0.40) was observed as compared with control. Tempered CHX 0.2% presented the highest probabilities of being ranked the most effective treatment (31.2%). Level of confidence varied from very low to moderate across all formulated comparisons. These findings summarize the current state of research evidence in the field of aerosolized bacteria in dentistry. Instigated by the era of SARS-CoV-2 pandemic, the stipulation of a broader evaluation of the aerosolized microbes, including viruses, potentially coupled with disinfectant-based prevention schemes should be prioritized.

Qualitative and quantitative analysis of bacterial aerosols in dental clinical settings: Risk exposure towards dentist, auxiliary staff, and patients

INTRODUCTION

Cross-infection or contamination are the major threats related to any medical profession. Microorganisms present in the dental clinic can cause cross-infection to the dentist, auxiliary staff and even towards the patients.

AIMS

The study was conducted to assess the level of atmospheric microbial contamination and composition of aerosols before, during and after dental treatment procedures in four clinical settings.

METHODS AND MATERIALS

The present study was conducted over a two-week period in a private dental college setting. An equal number of culture medium plates (blood agar) were placed 30 min prior to the initiation of work sessions in the selected area and 1 h after the working session began and after 2 h of cessation of the working period. After the collection of samples, the culture medium plates were incubated aerobically at 37°C in an incubator for 48 h. The number of colonies was expressed as colonies per media plate. After counting the colonies bacterial cell morphology was determined by a microscopic examination using a Reichert-Jung Series 150 light microscope.

STATISTICAL ANALYSIS

Statistical analysis such as ANOVA test for mean values and post hock was done using statistical package for social sciences (SPSS).

RESULTS

It shows that colony count increased after the working session and which reduced by itself once the working session was concluded which was significant (P < 0.001). The highest increase in the mean colony count was found in the department of periodontology during the treatment sessions. In the blood agar plates, the S. epidermidis was found maximum 62%, micrococcus was 22%, diphtheroid was 10%, fungi 4% and the least S. aureus 2%.

CONCLUSION

This study demonstrates that aerosols increase during and after work sessions and, therefore, increases the chance for infectious agent transmission in clinical settings.

Efficacy of High-volume Evacuator in Aerosol Reduction: Truth or Myth? A Clinical and Microbiological Study

Background and aims. Basic periodontal treatment aims at eliminating supra- and sub-gingival plaque and establishing conditions which will allow effective self-performed plaque control. This aim is primarily achieved with sonic and ultrasonic scalers. However, generation of bacterial aerosols during these procedures is of great concern to patients, the dentist and the dental assistant. The aim of this study was to compare the reduction in aerosol with and without high-volume evacuator through a microbiological study.

Materials and methods. For this clinical study a fumigated closed operatory was selected. Maxillary incisors and canines were selected as an area for scaling. Piezoelectric ultrasonic scaling was performed in the absence and in the presence of a high-volume evacuator at 12 and 20 inches from the patient's oral cavity. In both groups scaling was carried out for 10 minutes. Nutrient agar plates were exposed for a total of 20 minutes. After this procedure, nutrient agar plates were incubated in an incubator at 37°C for 24 hours. The next day the nutrient agar plates were examined for colony forming units by a single microbiologist.

Results. The results showed no statistically significant differences in colony forming units (CFU) with and without the use of a high-volume evacuator either at 12 or 20 inches from the patient's oral cavity.

Conclusion. It was concluded that high-volume evacuator, when used as a separate unit without any modification, is not effective in reducing aerosol counts and environmental contamination.

Risk factors associated with asthma phenotypes in dental healthcare workers

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

A study to evaluate and compare the efficacy of preprocedural mouthrinsing and high volume evacuator attachment alone and in combination in reducing the amount of viable aerosols produced during ultrasonic scaling procedure

BACKGROUND AND OBJECTIVES

In recent years, ultrasonics has gained prime importance and is considered a valuable tool in the dentist's armamentarium. Studies have confirmed that an aerosolized bacterial contamination is produced during the use of ultrasonic scalers.

AIM

To evaluate and compare the efficacy of preprocedural mouthrinsing using a bis-biguanide (chlorhexidine gluconate 0.2%) and high volume evacuator attachment alone and in combination in reducing the amount of viable aerosols produced during ultrasonic scaling procedure.

MATERIALS AND METHODS

A total 90 subjects were assigned to group I (who rinsed with 0.2% chlorhexidine gluconate prior to scaling), group II (high volume evacuator attachment was used during ultrasonic scaling) and group III (who rinsed with 0.2% chlorhexidine gluconate prior to scaling and in whom high volume evacuator attachment was used during ultrasonic scaling). Control group consisted of subject's whose mouth was scaled using a piezoelectric ultrasonic scaler without preprocedural rinsing or high volume suction. Aerosol samples were collected using blood agar plates. The blood agar plates containing the aerosol sample were taken to the microbiology department as soon as the sampling was over and were subjected to aerobic culturing.

RESULTS

The values obtained showed that all the three groups were effective in reducing the mean colony forming units (CFUs).

CONCLUSION

The results of this study showed that preprocedural rinse and high volume suction were effective when used alone as well as together in reducing the microbial load of the aerosols produced during ultrasonic scaling. There was a significant reduction in the number of CFUs in aerosol samples obtained.

Evaluation of Aerosol and Water Contamination and Control of Cross Infection in Dental Clinics

BACKGROUND

The oral cavity is an unique environment which provides an ideal medium for bacterial growth. As a result of repeated exposure to the microorganisms present in blood and saliva, the dental health professionals and the patients are at a higher risk for developing many infectious diseases. A pilot study was carried out in the Dept of Dental Surgery, Armed Forces Medical College to assess the risk of cross infection in dental clinics.

METHODS

Samples were collected from different dental surgeries of the Dept of Dental Surgery, Armed Forces Medical College and sent for microbiological culture and identification to the Dept of Microbiology, Armed Forces Medical College. The sampling was carried out in two stages, before and after implementing a set protocol.

RESULT

All dental unit waterlines were coated with a well established biofilm made up of filamentous and bacillus-like microorganisms in first stage of study. There was marked reduction in the number of colonies from the samples collected during second stage. Same findings were observed in the samples of aerosol produced by ultrasonic scalers.

CONCLUSION

The present study concluded that the new set protocol followed is significantly effective in reducing the microbial load in the water tubing, container and aerosol production. It is an effective measure for reducing the chances of cross infection in the dental surgery.

Italian multicenter study on infection hazards during dental practice: control of environmental microbial contamination in public dental surgeries

Background

The present study assessed microbial contamination in Italian dental surgeries.

Methods

An evaluation of water, air and surface microbial contamination in 102 dental units was carried out in eight Italian cities.

Results

The findings showed water microbial contamination in all the dental surgeries; the proportion of water samples with microbial levels above those recommended decreased during working. With regard to Legionella spp., the proportion of positive samples was 33.3%. During work activity, the index of microbial air contamination (IMA) increased. The level of microbial accumulation on examined surfaces did not change over time.

Conclusion

These findings confirm that some Italian dental surgeries show high biocontamination, as in other European Countries, which highlights the risk of occupational exposure and the need to apply effective measures to reduce microbial loads.

Sonic and ultrasonic scalers in periodontal treatment: a review

Periodontal therapy aims at arresting periodontal infection and maintaining a healthy periodontium. The periodic mechanical removal of subgingival microbial biofilms is essential for controlling inflammatory periodontal disease. Mechanical periodontal therapy consists of scaling, root planing and gingival curettage. The sonic and ultrasonic scalers are valuable tools in the prevention of periodontal disease. The vibration of scaler tips is the main effect to remove the deposits from the dental surface, such as bacterial plaque, calculus and endotoxin. However, constant flushing activity of the lavage used to cool the tips and cavitational activity result in disruption of the weak and unattached subgingival plaque. The aim of the study was to review the safety, efficacy, role and deleterious side-effects of sonic and ultrasonic scalers in mechanical periodontal therapy.

Isolation of pathogenic Legionella species and legionella-laden amoebae in dental unit waterlines

Legionella released into the air during treatment are a potential source of infection. Water stagnation in dental unit waterlines (DUWLs) creates biofilms and promotes the proliferation of these micro-organisms. This study investigated the presence of amoeba infected with legionella, L. pneumophila and other pathogenic Legionella species in a dental teaching hospital. Water samples were collected in the morning and afternoon from 99 dental units and 16 taps connected to the municipal water supply. Samples were plated on selective media and tested for legionella using the direct immunofluorescent antibody technique and the latex agglutination test. Legionella were found in 33% of the DUWLs and in 47% of the mains taps supplying these units. Legionella-laden amoebae occurred in one mains tap sample and in 20% of DUWLs in a clinic of the teaching hospital. L. micdadei was the predominant species isolated from this clinic. L. pneumophila serogroups 2-14 predominated in the mains water, whereas L. pneumophila serogroup 1 was found in approximately half of the contaminated DUWLs and mains taps irrespective of the time of sampling. Pathogenic Legionella species seeded by municipal water into DUWLs is a potential source of legionella infection for both dental personnel and patients during prolonged dental treatment. This problem is compounded by the presence of legionella-laden amoebae which may contain levels of organism well within the infective dose. The interaction of legionella with amoebae is an important ecological factor that may significantly increase the risk of legionellosis, and thus should be given further consideration in the refinement of risk assessment models.

Atmospheric contamination during ultrasonic scaling

OBJECTIVE

The aim of this study was to determine the microbial atmospheric contamination during initial periodontal treatment using a piezoelectric ultrasonic scaler in combination with either high-volume evacuation (HVE) or conventional dental suction (CDS).

METHODS

The study included 17 treatment sessions, consisting of a 40-min episode of continuous plaque and calculus removal using an ultrasonic unit (EMS). The treatment sessions were carried out in six patients with generalized adult periodontitis and ranged from two to four sessions per patient according to their needs. The use of HVE and CDS was randomly assigned over the sessions within each patient. Before each treatment, the operating room was not used for 15 h. To measure baseline microbial air pollution two Petri dishes containing blood agar were exposed for 10 min to the air. At the start of each treatment session, two Petri dishes were exposed for 5 min at a distance of 40 cm from the mouth of the patients. After 20 min, this procedure was repeated. At a distance of 150 cm, two Petri dishes were exposed for 20 min followed by exposure of two new Petri dishes for the rest of the session. The plates were cultured aerobically and anaerobically for 3 and 7 days, respectively.

RESULTS

The mean colony forming units (CFU) before treatment never exceeded 0.6 colonies per plate. At 40 cm, the mean CFU, when considering a period of 40 min, was 8.0 for HVE and 17.0 for CDS. The mean CFU at 150 cm during this period was 8.1 with HVE and 10.3 with the CDS. With reference to the Air Microbial Index the operatory atmosphere was considered to be in a good condition during 40 min of continuous use of the ultrasonic scaler in combination with both HVE and CDS.

CONCLUSION

Within the restrictions of this study, only limited atmospheric microbial contamination is produced when using a piezoelectric ultrasonic scaler.

Aerosols and splatter in dentistry: a brief review of the literature and infection control implications

Background

Aerosols and droplets are produced during many dental procedures. With the advent of the droplet-spread disease severe acute respiratory syndrome, or SARS, a review of the infection control procedures for aerosols is warranted.

Types of Studies Reviewed

The authors reviewed representative medical and dental literature for studies and reports that documented the spread of disease through an airborne route. They also reviewed the dental literature for representative studies of contamination from various dental procedures and methods of reducing airborne contamination from those procedures.

Results

The airborne spread of measles, tuberculosis and SARS is well-documented in the medical literature. The dental literature shows that many dental procedures produce aerosols and droplets that are contaminated with bacteria and blood. These aerosols represent a potential route for disease transmission. The literature also documents that airborne contamination can be minimized easily and inexpensively by layering several infection control steps into the routine precautions used during all dental procedures.

Clinical Implications

In addition to the routine use of standard barriers such as masks and gloves, the universal use of pre-procedural rinses and high-volume evacuation is recommended.

Ultrasonic dental scaler: associated hazards

BACKGROUND

The ultrasonic dental scaler is a valuable tool in the prevention of periodontal disease; however, this equipment has a number of hazards with which it is associated. These include heating of the tooth during scaling, vibrational hazards causing cell disruption, possible platelet damage by cavitation, associated electromagnetic fields that can interrupt pacemakers, auditory damage to patient and clinician and the release of aerosols containing dangerous bacteria.

OBJECTIVE

To collate the research reported on the various hazards associated with the ultrasonic dental scaler and discuss possible future research areas.

DATA SOURCES

The scientific literature was searched using Web of Science, EMBASE and Medline, and the results of these were then hand-searched to eliminate nonrelevant papers.

CONCLUSIONS

This review outlines some of the research conducted into these areas of associated hazard in order to assess their significance in the clinical situation, and discusses ideas for future research. Suggestions of recommendations are given, which have been previously investigated for their aid in reducing possible hazards, to ensure the safe working of ultrasonic scalers in the dental practice.

Bacterial aerosols in the dental clinic: a review

A number of sources of bacterial aerosols exist within and outside the dental clinic. The concentration of bacterial aerosols and splatters appears to be highest during dental procedures, especially those generated by some procedures such as ultrasonic scaling, or using a high speed drill. Several infectious diseases could be transmitted to staff and patients by airborne bacterial and other contaminants in the dental clinic. Air-conditioning and ventilation systems should be regularly maintained to reduce environmental contaminants and to prevent recirculation of bacterial aerosols. Pre-procedural rinsing by patients with mouthwashes as well as vacuum and electrostatic extraction of aerosols during dental procedures could also be employed. Dental staff should also consider appropriate immunizations and continue to use personal protective measures, which reduce contact with bacterial aerosols and splatters in the dental clinic.

Evaluation of environmental bacterial contamination and procedures to control cross infection in a sample of Italian dental surgeries

OBJECTIVES

To perform a pilot study on bacterial contamination in some dental surgeries (n=51) in a local health unit in Brescia (Lombardy Region, Italy) and to evaluate the procedures to control cross infection used by the personnel to reduce the risk of infection in dental practice.

METHODS

A survey was carried out by interviewing 133 dental personnel with a questionnaire on the procedures used to control infection. The autoclaves, chemical baths (chemiclaves), and ovens present in the surgeries were tested for sterilisation efficiency with a spore test, and already packed and sterilised instruments were randomly sampled and tested for sterility. Microbial contamination of air, surface, and dental unit water samples were also studied.

RESULTS

The dental personnel did not generally follow the principal procedures for infection control: 30% of personnel were not vaccinated against hepatitis B virus, infected instruments were often not decontaminated, periodic checks of autoclave efficiency were lacking, and the knowledge of disinfection mechanisms and procedures was incomplete. High bacteriological contamination of water at dental surgeries was often found and total bacteriological counts in air samples were high. Surface studies showed widespread bacterial contamination.

CONCLUSIONS

On the basis of these results, an educational programme for the prevention of infective hazards has been prepared and carried out. The results of this pilot study will be used for planning a national survey.

Bacterial aerosols in the dental clinic: effect of time, position and type of treatment

OBJECTIVES

The objectives of this study were to investigate changes in the concentration of total bacterial aerosols before, during, and after the working period at different positions within the same multichair dental clinics. Also to investigate the contribution to total bacterial aerosols, if any, of the aerosols generated from different types of dental procedures, as well as the environment.

METHODS

Air sampling using a Slit-to-Agar air sampler at three positions in a multichair dental clinic, performed three times per day over a three week period before work, during work and after work. The second part of the study, in another multichair dental clinic, was performed before working and during three types of dental procedures.

RESULTS

The concentration of total bacterial aerosols and Bacillus sp. in air which circulated in the dental clinic was lower at the end of the day than at the beginning. There was no significant change in the concentration of total bacterial aerosols in different positions in the dental clinic or after the three types of dental treatments. The concentration of Bacillus sp. in air not mainly generated during dental procedures and which may come from an environmental source, was reduced.

CONCLUSIONS

This study suggests that the proportions of different types of bacteria in air may change before, during and after dental treatment. Preventive measures may need to be instituted to reduce build up of bacterial aerosols in the dental clinic during non-working periods.

Assessing the clinical effectiveness of an aerosol reduction device for the air polisher

BACKGROUND

Because of the growing concern of the infectious nature of aerosols produced by air polishers, the Centers for Disease Control and Prevention and the American Dental Association have made recommendations to minimize dental aerosols. In addition, a device was developed in 1997 to reduce the aerosol generated during air polishing.

METHODS

The authors conducted a blinded clinical study to determine the effectiveness of an aerosol reduction device during air polishing. All 30 subjects underwent two minutes of air polishing, one with the aerosol reduction device on one side of the mouth and one without the device on the opposite side. Microbial samples were collected on blood agar plates positioned 12 inches from the subject's mouth and from one plate attached to the dental hygienist's face mask. The sample plates were then inverted and incubated for three days at 37 C.

RESULTS

Using the paired t-test, the authors found that the air polisher without the aerosol reduction device generated a significantly greater mean quantity of colony-forming units, or CFUs, 12 inches from the subject's mouth (mean +/- standard deviation, 148.00 +/- 145.00 CFUs) than the air polisher with the aerosol reduction device (20.10 +/- 53.90 CFUs) (P < .0001). In addition, the air polisher without the aerosol reduction device generated a significantly greater number of CFUs on the face mask plate (40.90 +/- 33.80 CFUs) than the air polisher with the aerosol reduction device (8.80 +/- 15.10 CFUs) (P < .0001).

CONCLUSION

The data suggest that the aerosol reduction device is effective in reducing the number of microorganisms generated during air polishing.

CLINICAL IMPLICATIONS

Air polishing with the aerosol reduction device may decrease the potential for disease transmission.

Aerosol and splatter production by focused spray and standard ultrasonic inserts

BACKGROUND

Control of contamination in the dental office has sometimes deterred practitioners from using ultrasonic scalers. Recent studies point to the aerosol and splatter produced during ultrasonic scaling as a vehicle for the possible transmission of bloodborne pathogens. A recently introduced ultrasonic insert that focuses the spray produced during scaling may reduce this aerosol contamination. An aerosol reduction device (ARD) that is attached to the ultrasonic handpiece has been shown to reduce the contamination cloud by placing suction in close proximity to the ultrasonic tip. The purpose of this study was to compare the contamination produced by a standard insert (S) and the new focused spray (F) insert with and without the use of the aerosol reduction device (ARD).

METHODS

The testing was conducted in vitro within a plastic enclosure using a dye in the coolant spray. After mock scaling of a dentoform model, the number of contaminated squares on the enclosure was counted and recorded.

RESULTS

Analysis of the data indicated no significant difference (P >0.05, Mann-Whitney U test) between the S or F inserts in the amount of contamination produced. When the aerosol reduction device was used, there was a significant reduction (P <0.05, Mann-Whitney U test) in the amount of contamination for both inserts with a greater reduction for the standard insert.

CONCLUSIONS

The traditional style of ultrasonic insert (S) and the newer focused coolant water insert (F) produce an equal amount of aerosol contamination. The amount of aerosol contamination produced by both inserts is copious. The ARD significantly reduced contamination with both styles of inserts. These findings support the use of a large bore high-volume evacuator whenever an ultrasonic scaler is used.

Aerosol and splatter contamination from the operative site during ultrasonic scaling

As concern about indoor air quality increases, attention is being placed on the aerosol and splatter produced during dental procedures. This study quantifies the contamination produced by ultrasonic scalers during in vitro scaling without coolant water. When compared with the handheld curette used as a control, all ultrasonic scalers and tips tested produced significant aerosol and splatter regardless of the type of scaler, the power level or the insert. The ADA-recommended method for controlling contaminated aerosol and splatter is the use of a large-bore high-volume evacuator. This study supports the ADA recommendation of use of a high-volume evacuator whenever ultrasonic scaling is performed.

Blood contamination of the aerosols produced by in vivo use of ultrasonic scalers

Disease transmission and barrier techniques during dental treatment have been areas of recent concern in dentistry. Ultrasonic scalers are known to produce aerosols, and these aerosols are often produced from areas of significant disease activity, including bleeding. This study was performed to determine if these aerosols contain blood from the gingival sulcus. Forty areas consisting of two contiguous periodontally involved teeth (probing depth of at least 5 mm on one site of each tooth) were scaled subgingivally with an ultrasonic scaler for 30 seconds. A high volume evacuator (HVE) tip was positioned 3 to 5 cm away from the operating site and utilized to capture the aerosols produced. The water remaining in and on the HVE tube was tested for occult blood by the guiac resin method. Gingival index, mean probing depth, presence of bleeding with scaling, and presence of visible blood in the HVE tip were recorded. All 40 test sites showed a positive result for blood in the captured aerosols despite the wide variation in the measured parameters. It may be concluded that subgingival scaling on periodontally involved teeth with ultrasonic scalers would be expected to produce aerosols containing blood.