Failure of non-vacuum steam sterilization processes for dental handpieces

Bacterial contamination of forehead skin and surgical mask in aerosol-producing dental treatment

Background

Bacterial contamination of dental professionals’ facial skin and protective equipment from treatment-related aerosols and droplets are poorly studied.

Methods

This prospective study analyzed samples from 67 consecutive aerosol-producing dental treatments. Sterile nylon swabs served to collect samples from dental professionals’ foreheads before and after exposure. Contact samples were obtained from used surgical masks. Samples were incubated on agar under aerobic and anaerobic conditions. Bacteria were classified by MALDI-TOF mass spectrometry. We determined the frequencies of obligate and facultative oral bacteria and scored bacterial growth (0: none; 1: < 100 colonies; 2: >100 colonies; 3: dense).

Results

Bacteria were detected in 95% of skin-swab and 76% of mask samples. Median bacterial scores were 2 for forehead samples before and after treatment, and 1 for masks. Obligate and facultative oral bacteria were more frequent (6% and 30%) in samples from exposed forehead skin, which also showed increased bacterial scores (28%). 5% of samples contained methicillin-sensitive Staphylococcus aureus; 3% contained obligate anaerobes.

Conclusion

Exposed forehead skin was significantly less contaminated with obligate oral bacteria than expected based on surgical mask findings. Exposed forehead skin showed increased contamination attributable to aerosol-producing procedures. The forehead’s physiological skin microbiota may offer some protection against bacterial contamination.

Bacterial Contamination of Equine Dentistry Equipment-Effect of Cleaning and Disinfection

Simple Summary

Some of the equipment used in equine dentistry is difficult to clean and disinfect. Since it is vital to avoid the spread of infections in equine healthcare it is important to develop practical and easy-to-follow methods for cleaning and disinfecting dental equipment. The aim of this study was to investigate hygiene in equine dentistry. Dental equipment and the head support, where horses rest their head during dental care, were sampled for the amount of bacteria between each patient before and after dental care as well as after cleaning and/or disinfecting. The amount of bacteria was, in general, high on dental equipment and the head support after dental procedures. Bacteria were found in different amounts on most of the dental equipment after cleaning or disinfecting, which indicates a risk for spreading infections when using the equipment. For the head support, cleaning and/or disinfecting generally resulted in a reduced amount of bacteria, indicating a lowered risk for spreading infections. There is a great need for evidence-based guidelines on hygiene in equine dentistry to decrease the risk of transmitting infections between patients, facilities, and stables.

Abstract

Equine dentistry has developed immensely and human dental equipment, such as handpieces, are often used. Measures to avoid the spread of infectious microorganisms are important, but this is challenging since handpieces are difficult to decontaminate. Thus, it is necessary to develop effective IPC measures in equine dentistry. The aim of this study was to contribute to the evidence needed for future evidence-based guidelines on IPC by investigating hygiene in equine dentistry. Used handpieces and dummies (i.e., handpieces not used during dental procedure, reflecting environmental bacterial contamination) and the head support were sampled each day before the first patient, for each patient after treatment, and after decontamination. All equipment was sampled with 3M ^TM Swab Samplers and the head support additionally sampled with dip slides. After dental procedures, the detected bacterial load was often high on used handpieces, dummies, and the head support. After decontamination, handpieces did not meet the criteria for high-level disinfected equipment. In all but one case decontamination of the head support resulted in a lowered bacterial load. There is a great need for evidence-based guidelines on hygiene in equine dentistry, including IPC measures, to decrease the risk of spreading infectious microorganisms between patients, facilities, and stables.

Sensors in the Autoclave-Modelling and Implementation of the IoT Steam Sterilization Procedure Counter

Surgical procedures involve major risks, as pathogens can enter the body unhindered. To prevent this, most surgical instruments and implants are sterilized. However, ensuring that this process is carried out safely and according to the normative requirements is not a trivial task. This study aims to develop a sensor system that can automatically detect successful steam sterilization on the basis of the measured temperature profiles. This can be achieved only when the relationship between the temperature on the surface of the tool and the temperature at the measurement point inside the tool is known. To find this relationship, the thermodynamic model of the system has been developed. Simulated results of thermal simulations were compared with the acquired temperature profiles to verify the correctness of the model. Simulated temperature profiles are in accordance with the measured temperature profiles, thus the developed model can be used in the process of further development of the system as well as for the development of algorithms for automated evaluation of the sterilization process. Although the developed sensor system proved that the detection of sterilization cycles can be automated, further studies that address the possibility of optimization of the system in terms of geometrical dimensions, used materials, and processing algorithms will be of significant importance for the potential commercialization of the presented solution.

Contamination of surgical mask during aerosol-producing dental treatments

Objectives

Surgical masks are usually contaminated during dental treatment. So far it has not been investigated whether a surgical mask itself can be a source of microbial transmission. The aim of this study was therefore to investigate the microbiological contamination of surgical masks during dental treatment and the transfer of microorganisms from the mask to the hands.

Materials and methods

Five dental treatment modalities were studied: carious cavity preparation (P-caries, n = 10), tooth substance preparation (P-tooth, n = 10), trepanation and root canal treatment (P-endo, n = 10), supragingival ultrasonic application (US-supra, n = 10), and subgingival periodontal ultrasonic instrumentation (US-sub, n = 10). Bacterial contamination of mask and gloves worn during treatment was tested by imprinting on agar plates. Additionally, before masks were tested, their outer surface was touched with a new sterile glove. This glove was also imprinted on agar. Bacteria were identified by MALDI TOF mass spectrometry. Colony-forming units (CFU) were scored: score 0: 0 CFU, score 1: < 10² CFU, score 2: > 10² CFU, score 3: dense microbial growth.

Results

All masks and all gloves used during treatment displayed bacterial contamination (sample scores 0/1/2/3: masks 0/46/3/1 and gloves 0/31/10/9). After touching the masks with new sterile gloves, microorganisms were recovered with the following contamination scores: P-caries: 4/6/0/0, P-tooth: 2/8/0/0: P-endo: 7/3/0/0, US-supra: 0/9/1/0, US-sub: 2/8/0/0. No statistically significant differences were detected between the treatment modalities. Streptococci spp. and Staphylococci spp. representing the oral and cutaneous flora dominated.

Conclusions

Surgical masks are contaminated after aerosol-producing dental treatment procedures. Used masks have a potential to be a source of bacterial contamination of the hands.

Clinical relevance

Dental staff should avoid touching the outer surface of masks with their hands to prevent transmission of pathogens. It is recommendable to change the mask after each treated patient followed by hand disinfection.

Autoclave sterilization of dental handpieces: A literature review

PURPOSE

The present review aimed to investigate autoclave sterilization of dental handpieces based on available studies.

STUDY SELECTION

The sterilizing efficiency of dental handpieces with autoclave is mainly affected by the types of apparatus (N, B, and S), the packaging with sterilizing pouch, cleaning, and lubrication. These subjects were reviewed based on the in vitro experimental studies.

RESULTS

Dental handpieces can be sterilized, including inactivation of heat-resistant bacterial spores, with type B or type S sterilizers, regardless of the use of a sterilization pouch. In contrast, although type N autoclaves are capable of sterilization of general bacteria such as Streptococcus salivarius even in a sterilization pouch if instruments are washed beforehand, complete sterilization of the wrapped handpiece is not always achieved. Therefore, to achieve sterilization efficiency with type N autoclaves, processing without any packaging is recommended. As regards cleaning of handpiece, although contamination decreases with irrigation and wiping of handpieces, all reports concluded that these treatments alone do not achieve complete decontamination of reusable handpieces.

CONCLUSION

Although type B and type S autoclaves allow us to sterilize the dental handpieces, it is important to realize that complete sterilization of the handpiece is not always achieved by type N autoclave. Understanding autoclave processing of handpieces is essential for dental practice to deliver the safe dental care.

Evaluation of the mechanical cleaning efficacy of dental handpieces

BACKGROUND

Dental handpieces undergo a decontamination process before reutilization. Thorough cleaning is a prerequisite to effective sterilization, to guarantee safety and prevent cross-infections.

AIM

To assess the cleaning efficacy offered by devices dedicated to dental handpieces.

METHODS

PIDTests©, which are patented tubes made of transparent material and designed to replace handpieces in cleaning devices, were artificially stained by Soil Test© (Browne/STERIS). Three cycles were performed with PIDTests© connected to every handpiece adapter in the four different machines tested: X-Cid 2© (Micro-Mega) with a total of nine PIDTests©; iCare+© (NSK) with nine PIDTests©; DAC Universal© (W&H) with 18 PIDTests©; and BioDA 80© (VR2M) with 24 PIDTests©. A visual evaluation and a biuret reaction test were performed.

FINDINGS

In three of the tested cleaning devices (X-Cid2©, iCare+© and DAC Universal©), all of the PIDTests© showed Soil Test© residues, on the internal and external surfaces indicating cleaning was ineffective. Only the BioDA 80© showed no residual stains on all the PIDTests© and negative biuret reaction test results, making the cleaning effective.

CONCLUSIONS

Manufacturers should optimize the cleaning device parameters, based on the Sinner circle (grouping compensatory parameters which influence the effectiveness of a cleaning process, such as pressure, temperature, time, detergent concentration), to improve cleaning efficacy and enable dental surgeons to ensure the safety. Although PIDTests© are the only tool to provide visual indications on the cleaning efficacy of washer-disinfectors dedicated to handpieces, manufacturers should continue with the development of improved and validated tools to assess cleaning efficacy.