Assessment of infectious diseases risks from dental aerosols in real-world settings

BACKGROUND: Infectious diseases physicians are leaders in assessing the health risks in a variety of community settings. An understudied area with substantial controversy is the safety of dental aerosols. Previous studies have used in vitro experimental designs and/or indirect measures to evaluate bacteria and viruses from dental surfaces. However, these findings may overestimate the occupational risks of dental aerosols. The purpose of this study was to directly measure dental aerosol composition to assess the health risks for dental healthcare personnel and patients. METHODS: We used a variety of aerosol instruments to capture and measure the bacterial, viral, and inorganic composition of aerosols during a variety of common dental procedures and in a variety of dental office layouts. Equipment was placed in close proximity to dentists during each procedure to best approximate the health risk hazards from the perspective of dental healthcare personnel. Devices used to capture aerosols were set at physiologic respiration rates. Oral suction devices were per the discretion of the dentist. RESULTS: We detected very few bacteria and no viruses in dental aerosols-regardless of office layout. The bacteria identified were most consistent with either environmental or oral microbiota, suggesting a low risk of transmission of viable pathogens from patients to dental healthcare personnel. When analyzing restorative procedures involving amalgam removal, we detected inorganic elements consistent with amalgam fillings. CONCLUSIONS: Aerosols generating from dental procedures pose a low health risk for bacterial and likely viral pathogens when common aerosol mitigation interventions, such as suction devices, are employed

Leishmania donovani infection induces anemia in hamsters by differentially altering erythropoiesis in bone marrow and spleen.

Leishmania donovani is a parasite that causes visceral leishmaniasis by infecting and replicating in macrophages of the bone marrow, spleen, and liver. Severe anemia and leucopenia is associated with the disease. Although immune defense mechanisms against the parasite have been studied, we have a limited understanding of how L. donovani alters hematopoiesis. In this study, we used Syrian golden hamsters to investigate effects of L. donovani infection on erythropoiesis. Infection resulted in severe anemia and leucopenia by 8 weeks post-infection. Anemia was associated with increased levels of serum erythropoietin, which indicates the hamsters respond to the anemia by producing erythropoietin. We found that infection also increased numbers of BFU-E and CFU-E progenitor populations in the spleen and bone marrow and differentially altered erythroid gene expression in these organs. In the bone marrow, the mRNA expression of erythroid differentiation genes (α-globin, β-globin, ALAS2) were inhibited by 50%, but mRNA levels of erythroid receptor (c-kit, EpoR) and transcription factors (GATA1, GATA2, FOG1) were not affected by the infection. This suggests that infection has a negative effect on differentiation of erythroblasts. In the spleen, erythroid gene expression was enhanced by infection, indicating that the anemia activates a stress erythropoiesis response in the spleen. Analysis of cytokine mRNA levels in spleen and bone marrow found that IFN-γ mRNA is highly increased by L. donovani infection. Expression of the IFN-γ inducible cytokine, TNF-related apoptosis-inducing ligand (TRAIL), was also up-regulated. Since TRAIL induces erythroblasts apoptosis, apoptosis of bone marrow erythroblasts from infected hamsters was examined by flow cytometry. Percentage of erythroblasts that were apoptotic was significantly increased by L. donovani infection. Together, our results suggest that L. donovani infection inhibits erythropoiesis in the bone marrow by cytokine-mediated apoptosis of erythroblasts

A Comparison of Aerosol Mitigation Strategies and Aerosol Persistence in Dental Environments

Abstract Objectives To determine the impact of various aerosol mitigation interventions and 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 (e.g, open bay, single room, partitioned operatories). We compared the impact of aerosol mitigation strategies [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 as aerosols are rapidly dispersed. Clinical Significance ISOVAC® HVE is highly effective in reducing aerosol emissions, with adequate ventilation and HVE use, dental fallow time can be reduced to 5 minutes

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

<i>L. donovani</i> infection increases apoptosis of erythroblasts.

<p>Apoptosis of bone marrow erythroblasts was examined by flow cytometry from control non-infected hamsters and <i>L. donovani</i> infected hamsters. Apoptosis was determined by Annexin-V binding (A) and the TUNEL Assay (B). Representative flow cytometry plots are from a control non-infected hamster and a hamster infected with <i>L. donovani</i> for 7 weeks. (A) Bone marrow cells were labeled with anti- E-cadherin antibody-e-Fluro 660 and FITC-Annexin V. Dead cells were excluded with 7-amino actinomycin (7-ADD). (B) BrdUTP incorporation by the TUNEL technique in erythroblasts was detected using Alexa-488 anti-BrdUTP and anti-E-cadherin-e-Fluro 660. (C) Percentage of E-cadherin positive erythroblasts that are Annexin-V positive. (D) Percentage of E-cadherin positive erythroblasts that are TUNEL positive. Data represent mean +/− SEM of 4 hamsters in each group. *p<0.05, Student’s t test.</p

Erythropoietin and Iron levels in infected hamsters.

<p>(A) Serum erythropoietin (Epo) levels in control hamsters and hamsters infected with <i>L. donovani</i> for 5 and 8 were determined by ELISA. EPO levels were significantly increased by infection, p<0.005, one-way ANOVA. (B) Serum iron levels in control and infected hamsters were determined by ferrozone assay. Serum iron levels were significantly decreased by infection, p<0.0005, one-way ANOVA. (C). Liver iron levels in control and infected hamsters were determined by ferrozone assay. Liver iron levels were significantly increased by infection p<0.05, one-way ANOVA.</p

Erythroid gene expression is differentially altered by <i>L. donovani</i> infection in the bone marrow and spleen.

<p>mRNA levels of erythroid genes were determined by real-time RT-PCR in bone marrow (A,C,E) and spleen (B, D, F). mRNA levels were normalized to β-actin and expressed relative to control non-infected hamsters. Data represent mean +/− SEM of 6–8 hamsters in each group. *p<0.05; **p<0.01, Student’s t test.</p