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.

Local Exhaust Ventilation to Control Dental Aerosols and Droplets

Dental procedures produce aerosols which 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. 10-minute crown preparations were performed with an air-turbine handpiece in the open plan clinic, and 10-minute 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 - 10.0 μm and liquid cyclone air samplers were used to capture aerosolised fluorescein tracer. Additionally, 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 (HEPA) 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.

Accelerated Bone Induction of Adult Rat Compact Bone Plate Scratched by Ultrasonic Scaler Using Acidic Electrolyzed Water

Fresh compact bone, the candidate graft material for bone regeneration, is usually grafted for horizontal bone augmentation. However, the dense calcified structure inhibits the release of growth factors and limits cellular and vascular perfusion. We aimed to create mechano-chemically altered dense skull bone by ultrasonic treatment, along with partial demineralization using commercially available acidic electrolyzed water (AEW). The parietal skull bone of an 11-month-old Wistar rat was exposed and continuously treated with a piezoelectric ultrasonic scaler tip for 1 min, using AEW (pH 2.3) or distilled water (DW, pH 5.6) as irrigants. Treated parietal bone was removed, cut into plates (5 × 5 × 1 mm3), grafted into the back subcutaneous tissues of syngeneic rats, and explanted at 1, 2, and 3 weeks. AEW bone showed an irregular surface, deep nano-microcracks, and decalcified areas. SEM-EDS revealed small amounts of residual calcium content in the AEW bone (0.03%) compared to the DW bone (0.86%). In the animal assay, the AEW bone induced bone at 2 weeks. Histomorphometric analysis showed that the area of new bone in the AEW bone at 2 and 3 weeks was significantly larger. This new combination technique of AEW-demineralization with ultrasonic treatment will improve the surface area and three-dimensional (3D) architecture of dense bone and accelerate new bone synthesis.

Photodynamic Therapy in Orthodontics: A Literature Review

Treatment of malocclusions using fixed orthodontic appliances makes it difficult for patients to perform hygiene procedures. Insufficient removal of bacterial biofilm can cause enamel demineralization, manifesting by visible white spot lesions or periodontal diseases, such as gingivitis periodontitis or gingival hyperplasia. The classic methods of preventing the above problems include, in addition to proper hygiene, ultrasonic scaling, periodontal debridement, and oral rinses based on chlorhexidine. New alternative methods of reducing plaque around brackets are being developed. There is a growing interest among researchers in the possibility of using photodynamic therapy in orthodontics. A literature search for articles corresponding to the topic of this review was performed using the PubMed and Scopus databases and the following keywords: ‘photodynamic therapy’, ‘orthodontics’, and ‘photosensitizer(s)’. Based on the literature review, two main directions of research can be distinguished: clinical research on the use of photodynamic therapy in the prevention of white spot lesions and periodontal diseases, and ex vivo research using a modified orthodontic adhesive by adding photosensitizers to them. Methylene blue is the most frequently used photosensitizer in clinical trials. The effectiveness of antimicrobial photodynamic therapy is mainly compared to the ultrasonic scaler as a single therapy or as an adjunct to the ultrasonic scaler. In their conclusions, the researchers most often emphasize the effectiveness of antimicrobial photodynamic therapy in reducing microbial levels in patients treated with fixed appliances and the possibility of using it as an alternative to routine procedures aimed at maintaining a healthy periodontium. The authors suggest further research on the use of photodynamic therapy to prove the validity of this method in orthodontics. It should also not be forgotten that proper hygiene is the basis for maintaining oral cavity health, and its neglect is a contraindication to orthodontic treatment.

Surface Roughness and Streptococcus mutans Adhesion on Metallic and Ceramic Fixed Prosthodontic Materials after Scaling

The aim of this study was to evaluate the surface roughness of fixed prosthodontic materials after polishing or roughening with a stainless steel curette or ultrasonic scaler and to examine the effect of these on Streptococcus mutans adhesion and biofilm accumulation. Thirty specimens (10 × 10 × 3 mm3) of zirconia (Zr), pressed lithium disilicate (LDS-Press), milled lithium disilicate glazed (LDS-Glaze), titanium grade V (Ti) and cobalt-chromium (CoCr) were divided into three groups (n = 10) according to surface treatment: polished (C), roughened with stainless steel curette (SC), roughened with ultrasonic scaler (US). Surface roughness values (Sa, Sq) were measured with a spinning disc confocal microscope, and contact angles and surface free energy (SFE) were measured with a contact angle meter. The specimens were covered with sterilized human saliva and immersed into Streptococcus mutans suspensions for bacterial adhesion. The biofilm was allowed to form for 24 h. Sa values were in the range of 0.008–0.139 µm depending on the material and surface treatment. Curette and ultrasonic scaling increased the surface roughness in LDS-Glaze (p < 0.05), Ti (p < 0.01) and CoCr (p < 0.001), however, surface roughness did not affect bacterial adhesion. Zr C and US had a higher bacterial adhesion percentage compared to LDS-Glaze C and US (p = 0.03). There were no differences between study materials in terms of biofilm accumulation.

Virus transmission by ultrasonic scaler and its prevention by antiviral agent

ABSTRACTDuring an ultrasonic scaler (USS) operation, droplets and aerosol are generated that may contribute to the transmission of viruses contained in saliva and gingival crevicular fluid. The purpose of this research was to develop an experimental model for testing the spread of viruses during USS instrumentation and to examining the prevention of spreading by replacing the coolant with an antiviral agent. In a virus transmission tunnel, USS operation with saline coolant and delivery of a viral suspension to the vicinity of USS tip generated droplets and aerosol containing Equine Arteritis Virus (EAV). Evaluation of droplet transmission was evaluated with adherent 48h cell culture monolayer RK13 cell lines in standard 48-well-plates positioned at a distance from 30 to 55 cm. The aerosol was collected by a cyclone aero-sampler flow of 100l/min. Antiviral activity of 0.25% sodium hypochlorite or electrolyzed water (EOW) was tested by suspension test. The two tested antiviral agents’ transmission prevention ability was evaluated by repeating the same experiment as with saline coolant. All experiments were repeated twice. With saline coolant, the cytopathic effect on cells was found in cells up to the distance of 45 cm, with the number of infected wells decreasing with distance. Viral particles were detected in only one AS in a very low concentration (≤4.2 TCID50/ml). In suspension test of 0.25% NaOCl and EOW, the TCID50/ml was below detection limit after 5s. With both antiviral agents, no cytopathic effect was found. However, the cytotoxic effect of 0.25% NaOCl was evident up to the distance of 35 cm. By USS activity, EAV could be transmitted by droplets up to a distance of 45 cm. Both antiviral agents could prevent virus droplet transmission. The transmission of EAV by aerosol yielded inconclusive results.

Mechanical Properties and Wear Resistance of Commercial Stainless Steel Used in Dental Instruments

The aim of this study was to investigate the element composition and grain size of commercial dental instruments used for ultrasonic scaler tips, which are composed of stainless-steel materials. The differences in mechanical properties and wear resistances were compared. The samples were classified into 4 groups in accordance with the manufacturer, Electro Medical Systems, 3A MEDES, DMETEC and OSUNG MND, and the element compositions of each stainless-steel ultrasonic scaler tip were analyzed with micro-X-ray fluorescence spectrometry (μXRF) and field-emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray spectroscopy (EDS). One-way ANOVA showed that there were significant differences in shear strength and Vickers hardness among the stainless-steel ultrasonic scaler tips depending on the manufacturer (p < 0.05). The mass before and after wear were found to have no significant difference among groups (p > 0.05), but there was a significant difference in the wear volume loss (p < 0.05). The results were then correlated with μXRF results as well as observations of grain size with optical microscopy, which concluded that the Fe content and the grain size of the stainless steel have significant impacts on strength. Additionally, stainless-steel ultrasonic scaler tips with higher Vickers hardness values showed greater wear resistance, which would be an important wear characteristic for clinicians to check.

Aerosol generation and control in the dental operatory: An in vitro spectrometric study of typical clinical setups

Dental turbines and scalers, used every day in dental operatories, feature built-in water spray that generates considerable amounts of water aerosol. The problem is that it is not exactly known how much. Since the outbreak of COVID-19, several aerosol safety recommendations have been issued—based on little empirical evidence, as almost no data are available on the exact aerosol concentrations generated during dental treatment. Similarly, little is known about the differences in the efficacy of different commercially available aerosol control systems to reduce in-treatment aerosol load. In this in vitro study, we used spectrometry to explore these questions. The time-dependent effect of conventional airing on aerosol concentrations was also studied. Everyday patient treatment situations were modeled. The test setups were defined by the applied instrument and its spray direction (high-speed turbine with direct/indirect airspray or ultrasonic scaler with indirect airspray) and the applied aerosol control system (the conventional high-volume evacuator or a lately introduced aerosol exhaustor). Two parameters were analyzed: total number concentration in the entire measurement range of the spectrometer and total number concentration within the 60 to 384 nm range. The results suggest that instrument type and spray direction significantly influence the resulting aerosol concentrations. Aerosol generation by the ultrasonic scaler is easily controlled. As for the high-speed turbine, the efficiency of control might depend on how exactly the instrument is used during a treatment. The results suggest that scenarios where the airspray is frequently directed toward the air of the operatory are the most difficult to control. The tested control systems did not differ in their efficiency, but the study could not provide conclusive results in this respect. With conventional airing through windows with a standard fan, a safety airing period of at least 15 minutes between treatments is recommended.