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.

Clinical evaluation of chlorine dioxide for disinfection of dental instruments.

This study aimed to clinically evaluate the disinfection efficacy of chlorine dioxide (ClO2) for used dental instruments. An imprint culture technique demonstrated that ultrasonic cleaning of intraorally applied dental mirrors in 0.02% ClO2 for 10 minutes resulted in compete removal of microorganisms for 10 subjects. Hepatitis C virus (HCV) RNA was detected by real-time polymerase chain reaction on periodontal curettes after subgingival scaling in four HCV-infected patients and was completely removed by the same treatment procedure. Therefore, the combination of ultrasonic cleaning with ClO2 may provide an alternative to toxic disinfectants, such as glutaraldehyde and sodium hypochlorite, for disinfecting dental instruments.

Bioassay studies support the potential for iatrogenic transmission of variant Creutzfeldt Jakob Disease through dental procedures.

BACKGROUND: Evidence is required to quantify the potential risks of transmission of variant Creutzfeldt Jakob (vCJD) through dental procedures. Studies, using animal models relevant to vCJD, were performed to address two questions. Firstly, whether oral tissues could become infectious following dietary exposure to BSE? Secondly, would a vCJD-contaminated dental instrument be able to transmit disease to another patient? METHODS: BSE-301V was used as a clinically relevant model for vCJD. VM-mice were challenged by injection of infected brain homogenate into the small intestine (Q1) or by five minute contact between a deliberately-contaminated dental file and the gingival margin (Q2). Ten tissues were collected from groups of challenged mice at three or four weekly intervals, respectively. Each tissue was pooled, homogenised and bioassayed in indicator mice. FINDINGS: Challenge via the small intestine gave a transmission rate of 100% (mean incubation 157±17 days). Infectivity was found in both dental pulp and the gingival margin within 3 weeks of challenge and was observed in all tissues tested within the oral cavity before the appearance of clinical symptoms. Following exposure to deliberately contaminated dental files, 97% of mice developed clinical disease (mean incubation 234±33 days). INTERPRETATION: Infectivity was higher than expected, in a wider range of oral tissues, than was allowed for in previous risk assessments. Disease was transmitted following transient exposure of the gingiva to a contaminated dental file. These observations provide evidence that dental procedures could be a route of cross-infection for vCJD and support the enforcement of single-use for certain dental instruments.

Costs of a limited patient notification exercise following infection control failures in a dental surgery.

In February 2008, a primary care trust in Cheshire Merseyside was notified of failures in the infection control practises of a dentist working in a large group practice. On advice from national experts, a look-back was undertaken to identify any patients infected with hepatitis followed by a notification exercise of patients who had received invasive treatment immediately afterwards. One patient with hepatitis C (HCV) was identified. Sixty patients were notified by letter and offered advice and HCV screening. The total cost of the patient notification exercise (PNE) was estimated at £85,936, equating to £1,562.47 per patient who responded to the notification (55), or £2,455.31 per patient screened (35). All results were negative. While this adds to evidence that the risk to patients in such incidents is small, failing to investigate the possibility that BBV transmission has occurred would carry public health, reputational and legal risks. Conducting a PNE in the first instance for those patients at highest risk, with the option of extending it if evidence of patient-to-patient transmission is found, ensures that the total costs of dealing appropriately with such incidents - while still substantial - are at least kept to a minimum.

Infection control failures in a dental surgery--dilemmas in incident management.

Three separate incidents involving failure of decontamination of dental instruments were reported to our Unit in less than one year. We describe the risk assessment we undertook for the likelihood of detecting transmission of a blood borne virus infection. Even where 4000 patients attended the same dentist for seven years, there was no certainty of detecting even one person infected by the decontamination failure, while several people who had acquired infection by other routes would be identified. We conclude that these findings suggest that notifying patients is not usually justified.

Risk of hepatitis B virus transmission via dental handpieces and evaluation of an anti-suction device for prevention of transmission.

We evaluated the risk of hepatitis B virus (HBV) transmission via dental handpieces and the effects of an anti-suction device in preventing HBV contamination. The results of our study show that under certain conditions, HBV transmission can occur when an anti-suction device is used during dental procedures. We conclude that such devices may decrease contamination, but do not eliminate it.

Surveillance of viral contamination of invasive medical instruments in dentistry.

OBJECTIVE: To investigate the viral contamination of invasive medical instruments in dentistry and to provide health administrative institutions with surveillance data. METHODS: Sterilized samples were randomly collected from the department of dentistry to detect HBV-DNA, HCV-RNA, HIV-RNA and HBsAg. RESULTS: Of the invasive medical instruments that were sterilized with 2% glutaraldehyde, one of the samples was positive for HBV-DNA, and another sample was positive for HBsAg. CONCLUSION: Though massive virus contamination of invasive medical instruments in dentistry has been reduced to a low level, the occurrence of contamination still remains.

[The possibility of hepatitis B virus transmission through dental handpieces].

OBJECTIVE: To discuss the possibility of hepatitis B virus (HBV) transmission through dental handpieces. METHODS: Investigation was carried on methods for disinfecting and sterilizing dental handpieces and the condition of HBsAg contamination on dental handpieces before and after disinfection and sterilization by randomly sampling all special stomatological hospitals and dental clinics in a same city and 10 dental departments from the third, second and first class hospitals. The possibility of HBV transmission through dental handpieces was probed by investigating whether ducks can be infected by bath liquid of dental handpieces contaminated by DHBV, while in such bath liquid, DHBV can not be detected by serum dot hybridization. RESULTS: From 2001 to 2004, in methods to disposing dental handpieces, the use of autoclave was remarkably increased while of the disinfectant wipe, immersion and other methods was remarkably decreased. The positive rate of HBsAg from dental handpieces in practice was 1.65%. It was evident that the bath liquid of dental handpieces contaminated by DHBV can conduct infection in vivo test of duck, while DHBV can not be detected in such bath liquid by serum dot hybridization, it is proved that the negative result of HBsAg in non-sterilized dental handpieces can not eliminate the possibility of HBV transmission through dental handpieces. CONCLUSION: There might exist the possibility of HBV transmission through dental handpieces however, the autoclaves might kill the virus contaminating on dental handpieces.

Removing hepatitis C virus from polytetrafluoroethylene-coated orthodontic archwires and other dental instruments.

The efficacy of removing, rather than destroying, hepatitis C virus (HCV) from polytetrafluoroethylene (PTFE)-coated orthodontic archwirs was tested. PTFE-coated archwires, pieces of PTFE and endodontic files (20 each) were immersed in HCV-infected blood for 24 hours. Half were washed under running water for 10 seconds while the remainder were thoroughly scrubbed with a toothbrush under running water for 10 seconds. Items were kept in separate dishes of distilled water for 24 hours. Reverse transcription polymerase chain reaction was used for viral replication. Viruses were detected by the gel method using a transilluminator. Only scrubbed PTFE pieces and coated archwires were negative for HCV. This suggests that PTFE coating of dental instruments inhibited HCV adhesion when thoroughly scrubbed.

[Efficiency of combined action of a chemical disinfectant and plasma sterilization on stomatological instruments and casts]. / Effektivnost' kombinirovannogo vozdeistviia khimicheskogo dezinfektanta i plazmennoi sterilizatsii na stomatologicheskie instrumenty i slepochnye materialy.

The efficiency of combined treatment of dentures by argon plasma and chemical disinfectant Ocadez is compared using anaerobic culturing of oral bacteria and polymerase chain reaction with hepatitis B, C, and D virus primers. Different protocols of processing dental instruments and casts directly after dentist's manipulations with outpatients were tried and model experiments with hepatitis viruses were carried out. The optimal protocol of plasma sterilization is as follows: 10 min at 86-90 degrees C after treatment with Ocadez or 15 min without additional chemical treatment.

Disinfection of dental diamond burs contaminated with hepatitis B virus.

STATEMENT OF PROBLEM: Hepatitis B infection (HBV) is a significant hazard in the dental environment because the virus may be transmitted through contaminated dental instruments. PURPOSE: This study determined whether cold disinfectants can inactivate HBV DNA and HBV surface antigens on diamond burs contaminated with HBV and whether ultrasonication can increase the antiviral properties of these agents. MATERIAL AND METHODS: Sterile dental diamond burs were contaminated with serum from a patient who tested positive for HBV surface antigen and hepatitis B viral DNA. The burs were air dried and placed in solutions containing either Cidex, Asepsys, TBS, Rotagerm, Virkon disinfectants, or a control phosphate buffered saline. Burs were divided into 2 groups and disinfected for 15 minutes. The first group was ultrasonicated; the second group was not ultrasonicated during disinfection. All the burs were transferred to phosphate buffered saline and ultrasonicated to remove any remaining viral particles. The ultrasonicate was tested for the presence of HBV surface antigen with a microparticle enzyme immunoassay and for hepatitis B viral DNA with a chemiluminescent molecular hybridization assay. RESULTS: TBS did not require ultrasonication to inactivate viral DNA and surface antigen. Rotagerm and Virkon inactivated surface antigen and viral DNA only with ultrasonication. Cidex and Asepsys inactivated viral DNA but not surface antigen with ultrasonication. CONCLUSION: The chlorine containing compound TBS was the most active disinfectant tested and did not require ultrasonication to destroy HBV. The remaining disinfectants should be used with ultrasonication to inactivate HBV.