Rotary dental instruments and the potential risk of transmission of infection: herpes simplex virus

A commentary on a flawed public health investigation

The possibility of hepatitis C being transmitted between dental patients was the genesis of an extensive and expensive look-back investigation conducted by an Ontario Public Health Unit. This investigation was performed with a minimal knowledge of nosocomial infections of dental origin, an enthusiastic reliance on untested checklist indicators and an absence of any of the criteria justifying such an investigation. As a consequence, the entire exercise was based on the false premise that an infection control lapse had occurred. This commentary will address these flaws, and other aspects of the Public Health Unit's response that detracted from its credibility. The provision of a realistic assessment of disease transmission in dentistry should result in Public Health Units conducting informed and mutually beneficial inspections of dental practices.

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.

Failure of non-vacuum steam sterilization processes for dental handpieces

BACKGROUND

Dental handpieces are used in critical and semi-critical operative interventions. Although some dental professional bodies recommend that dental handpieces are sterilized between patient use there is a lack of clarity and understanding of the effectiveness of different steam sterilization processes. The internal mechanisms of dental handpieces contain narrow lumens (0.8-2.3 mm) which can impede the removal of air and ingress of saturated steam required to achieve sterilization conditions.

AIM

To identify the extent of sterilization failure in dental handpieces using a non-vacuum process.

METHODS

In-vitro and in-vivo investigations were conducted on widely used UK bench-top steam sterilizers and three different types of dental handpieces. The sterilization process was monitored inside the lumens of dental handpieces using thermometric (TM; dataloggers), chemical indicator (CI), and biological indicator (BI) methods.

FINDINGS

All three methods of assessing achievement of sterility within dental handpieces that had been exposed to non-vacuum sterilization conditions demonstrated a significant number of failures [CI: 8/3024 (fails/no. of tests); BI: 15/3024; TM: 56/56] compared to vacuum sterilization conditions (CI: 2/1944; BI: 0/1944; TM: 0/36). The dental handpiece most likely to fail sterilization in the non-vacuum process was the surgical handpiece. Non-vacuum sterilizers located in general dental practice had a higher rate of sterilization failure (CI: 25/1620; BI: 32/1620; TM: 56/56) with no failures in vacuum process.

CONCLUSION

Non-vacuum downward/gravity displacement, type N steam sterilizers are an unreliable method for sterilization of dental handpieces in general dental practice. The handpiece most likely to fail sterilization is the type most frequently used for surgical interventions.

The extent of environmental and body contamination through aerosols by hydro-surgical debridement in the lumbar spine

INTRODUCTION

Surgical site infections occur in 1-6% of spinal surgeries. Effective treatment includes early diagnosis, parenteral antibiotics and early surgical debridement of the wound surface.

MATERIALS AND METHODS

On a human cadaver, we executed a complete hydro-surgery debridement including a full surgical setup such as draping. The irrigation fluid was artificially contaminated with Staphylococcus aureus (ATCC 6538). Surveillance cultures were used to detect environmental and body contamination of the surgical team.

RESULTS

For both test setups, environmental contamination was observed in an area of 6 × 8 m. Both test setups caused contamination of all personnel present during the procedure and of the whole operating theatre. However, the concentration of contamination for the surgical staff and the environment was lower when an additional disposable draping device was used.

CONCLUSIONS

The study showed that during hydro-surgery debridement, contaminated aerosols spread over the whole surgical room and contaminate the theatre and all personnel.

Can oil lubricated dental handpieces be sterilized?: Part 2. Literature review

A literature search revealed six laboratory-based microbial challenge studies which support the opinion that oil contamination does not prevent successful sterilization of the lumen of dental handpieces. However, a detailed appraisal of these papers revealed lack of detail in the cleaning methods used prior to sterilization and none of the papers considered the risks of prion contamination.

CLINICAL RELEVANCE

An examination of the evidence base on sterilization of oil-lubricated handpieces is of potential value to dental clinicians and their teams.

The effect of a disinfectant/coolant irrigant on microbes isolated from dental unit water lines

The purpose of this study was to assess water samples from a hospital dental clinic to determine whether a disinfectant/coolant irrigant containing chlorhexidine (Lines, Micrylium Laboratories) affects the presence of microbial organisms in dental unit waterlines. Water samples from three hospital dental operatories were collected at baseline and after overnight treatment with a disinfectant-containing irrigant followed by sterile water irrigation. Saliva of treated patients and sterile water rinse specimens were collected from the waterlines of these operatories for three consecutive days, then weekly for eight weeks after treatment. Specimens were cultured to identify total heterotrophic plate counts as well as presence of Pseudomonas aeruginosa and Candida species. Baseline organism counts varied from 10(3) to 10(5) colony-forming units per milliliter. After treatment, no organisms were detected in waterline discharge. Decontamination of dental unit waterlines is possible using a disinfectant/irrigant followed by sterile water irrigation. The potential for contamination of the lines from patients' saliva may have been reduced due to use of anti-retraction valves and the disinfectant/sterile water irrigation, as conducted in this study.

Environmental and body contamination through aerosols produced by high-speed cutters in lumbar spine surgery

STUDY DESIGN

A cadaver study to evaluate contamination in the operating room through the use of a high-speed bone cutter.

OBJECTIVES

To determine the grade of contamination of animate and inanimate objects through an aerosol intraoperatively, produced by a high-speed cutter during lumbar laminectomy.

SUMMARY OF BACKGROUND

In spinal surgery, high-speed cutters are used that produce an aerosol consisting of a mixture of irrigation solution, blood, and tissue debris. Such aerosols can be contaminated with potential pathogens. The surgical personnel and the environment are therefore exposed to a contamination risk.

METHODS

Laminectomies at three points (L2-L4) were performed on a human cadaver using a high-speed cutting device. The aerosol produced by the irrigation solution was contaminated with Staphylococcus aureus ATCC 12600. To detect the contamination of the environment and of the surgical team, surveillance cultures were used.

RESULTS

By air sampling, staphylococci were detected in the operating room at an extension of 5 by 7 m. The surgical team showed extensive face and body contamination with S. aureus. Despite protection by a barrier drape, similar contamination was observed on both the cadaver's head and the anesthesiologist.

CONCLUSIONS

The use of high-speed cutters in spinal surgery produces an aerosol that can be contaminated with blood-borne pathogens from infected patients. This aerosol is spread over the whole surgical room and contaminates the room and all personnel present. It is therefore critical to ensure that effective infection control measures are performed, not only by the surgeons but by everyone present in the operating room. The room itself must be sufficiently disinfected after such procedures.

Contamination risk of the surgical team through ROBODOC's high-speed cutter

During cutting of the femoral cavity in the ROBODOC procedure, an aerosol cloud of irrigation fluid, blood, and tissue debris was seen. This cloud potentially is contaminated with bacterial and viral vectors, which is an infection risk for the surgical team. A flat and a ball cutter were tested in four standard situations macroscopically with a colored solution. In a second experiment, the cutter was exposed to a fluid contaminated with Staphylococcus aureus, and bacterial room contamination was detected using standard cultures. The aerosol cloud was seen in a 6 x 3.6-m area. Extension and concentration varied, depending on the irrigation situation. ROBODOC's high-speed cutter produces an aerosol cloud in an area in which all members of the surgical team are affected. Sufficient protection is necessary for everyone in the operating room.

Effect of steam sterilization inside the turbine chambers of dental turbines

OBJECTIVE

It has been demonstrated that contamination of the insides of high-speed dental turbines occurs and that bacteria as well as viruses may remain infectious when expelled from such turbines during subsequent use. Consequently, it has been widely recommended that a high-speed turbine be sterilized after each patient. The purpose of this study was to evaluate the effect of steam autoclaving on a high-speed dental turbine with a contaminated turbine chamber.

STUDY DESIGN

Streptococcus salivarius and endospores of Bacillus stearothermophilus were used as test organisms to determine the effectiveness of 4 different small non-vacuum autoclaves and one vacuum autoclave.

RESULTS

The study demonstrated different efficiencies among the small non-vacuum autoclaves, the best showing close to a 6 log reduction of the test organisms inside the turbine chamber. When cleaning and lubrication of the high-speed dental turbine was carried out before autoclaving, this level of reduction was observed for all the examined non-vacuum autoclaves.

CONCLUSIONS

It is concluded that cleaning before sterilization is essential for safe use of high-speed dental turbines and that small non-vacuum autoclaves should be carefully evaluated before being used for the reprocessing of hollow instruments such as high-speed turbines.

Oral shedding of herpes simplex virus type 1: a review

Herpes simplex virus type 1 (HSV-1) and, to a lesser extent, type 2 (HSV-2) are the aetiological agents of recrudescent herpes labialis (RHL). The available literature on patterns of HSV-1 shedding into the oral cavity at the prodromal stage of disease, during recrudescences and also during asymptomatic periods, is reviewed, as are the potential sources of virus and the known trigger factors leading to viral reactivation. Attention is given to the methodologies in use for the detection of HSV-1 and the relevance to the risk of cross-infection in surgery. This review also discusses the increase in incidence of HSV-1 genital infections and the significance of salivary inhibitors of the herpes simplex type 1 virus.