Comment

The Biofilm Problem and a Few Simple Solutions

George K. Merijohn, DDS

Copyright 2001 Journal of the California Dental Association.

The May 2001 Journal of the California Dental Association cover story, "The Biofilm Problem," provided a valuable look at the ubiquitous nature of biofilm. I commend the authors, Dr. Wenyuan Shi, Dr. Casey Chen, and Ms. Elinor deLancey Pulcini, for their in-depth analysis of the subject, covering aspects such as biofilm formation, complexity, worldwide presence, and pervasiveness in clinical dentistry. Dr. Shi and Ms. Pulcini both recognized that the quality of dental water is critical in terms of patient contamination risk.

Although this understanding of the nature of biofilm is very important, dentistry still has not developed foolproof methods to fully protect at-risk patients from the disease-transmission potential associated with dental unit waterlines.

As pointed out in his excellent introduction to the CDA Journal issue, John W. Beierle, PhD, indicated that a number of patients are at high risk for disease transmission from a buildup of human pathogenic bacteria in dental unit waterlines. This group includes patients who are very young; very old; infirm; undergoing chemotherapy or radiation therapy; or immunosupressed from HIV infection, AIDS, organ transplants, and other conditions.

This is a large and increasing segment of our population, yet we cannot always identify these at-risk patients before dental treatment. Some dental patients have at-risk conditions not yet diagnosed. It is impossible, therefore, to know with certainty which patients are most susceptible to disease transmission from dental unit waterlines.

Likewise, it is impossible always to determine in advance of treatment which dental patients are capable of transmitting diseases. As a result, the dental profession adopted the universal precaution protocol for infection control: Every patient is assumed to be capable of transmitting diseases in the dental office and therefore identical infection control precautions are taken with all patients regardless of their health history. An obvious solution to the dental unit waterline dilemma is to establish a "universal precaution" protocol and assume that every patient is at significant risk of disease transmission from waterlines. Therefore, all patients would receive only sterile irrigant for every dental procedure. That means, of course, that every irrigation device -- including all dental drills, three-way syringes, and ultrasonic scalers -- must deliver sterile output irrigant to the patient. Unfortunately, this capability is lacking in the vast majority of equipment systems used in clinical dentistry today.

The waterline preventive measures currently practiced in the majority of dental offices fall short of the ideal goal. Flushing dental unit waterlines might lower the bioburden mass, but it does not eliminate human pathogens. Furthermore, from a microbiological standpoint, dental unit waterline disinfection can cause overpopulation of potentially pathogenic organisms that are not susceptible to the disinfectant. And, although special "micro" filters are available to attach to waterlines, they still allow human pathogens to pass through to the patient.

Hopeless situation? Not at all! Looking at the problem from a different perspective offers practical, cost-effective, time-efficient, and surprisingly simple solutions. The article "Prevention of Bacterial Endocarditis: Recommendations" (Journal of the American Dental Association, Vol. 128, August 1997, and Journal of the American Medical Association 1997, 277:1794–1801) cited the following dental procedures as high risk for producing bacteremia:

* Dental extractions;

* Periodontal therapy (surgery, scaling and root planning, probing, recall maintenance, subgingival placement of antibiotic fibers/strips);

* Prophylactic cleaning of teeth or implants where bleeding is anticipated;

* Endodontic surgeries that require the incision of or reflection of gingival or mucosa;

* Dental implant placement and replantation of avulsed teeth;

* Initial placement of orthodontic bands (not brackets);

These are the highest risk dental procedures in terms of disease transmission from contaminated dental unit waterlines because they either cause or are associated with bleeding and therefore are considered invasive by nature. They are by far the most important procedures for which to deliver sterile output irrigant. If clinicians first focused on making these procedures safe, patients and dentistry alike would benefit greatly.

There is no question that there are "gray-zone" situations and procedures in general dentistry for which it may be difficult to plan. For instance, the gum may bleed if the high-speed drill nicks it during tooth preparation. However, it is best for patients’ welfare and the profession not to suffer the institutional paralysis that comes with trying to define a solution for every clinical situation before instituting important change. The dental profession should immediately implement solutions for the already published and clearly defined at-risk procedures, and then consider other situations thereafter.

The solutions offered here for consideration are remarkably easy. A typical dental practice can implement them in a matter of days. Our private practice has had these protocols in place for more than five years. These solutions are clinically effective and are time- and cost-efficient (see report by G. K. Merijohn, DDS, published in CDA Update: Vol. 9, No.6, June 17, 1997).

Clinicians performing any of the high-risk dental procedures listed above should address three critical decision-making criteria:

Will a Dental Drill Be Used During the Procedure?

If so, the drilling system should be designed to pass sterile irrigant through sterile tubing and exit a sterile handpiece. The traditional dental high-speed handpiece with its waterline is incapable of meeting these criteria. However, drilling systems that deliver sterile output irrigant are readily available and not prohibitively expensive. For clinicians who only occasionally perform invasive procedures with a dental drill, portable dental units are available that cost from $2,500 to $4,500 and can be moved from one operatory to another. The irrigant costs approximately $2 per single-use disposable bag (250 ml of sterile IV saline solution).

The drilling speed may be a little slow for routinely cutting hard metal alloy restorations; but for surgical procedures (including sectioning restored teeth), these systems work very well. In fact, slower drills are better for surgical procedures: They cause much less trauma to the bone than the high-speed drills commonly used in dental surgery.

Will Irrigation Be Needed During the Procedure?

Examples of irrigation include flushing in a gingival sulcus, flushing under a tissue flap, and flushing an open wound (e.g., a gingivectomy or extraction site). Although many clinicians rely on the readily available three-way air-water syringe attached to the dental unit waterline for irrigation, there are safer and better ways to irrigate wounds and/or bleeding areas.

To eliminate waterline contamination risks, the clinician can simply do the following:

* Pour sterile water ($1.50 per 250ml multi-use bottle) into a disposable cup or sterilized container, if preferred;

* From the cup, fill a new 10 cc disposable syringe ($0.11–$0.50 per unit) that was pre-sterilized in the sterilizer;

* Irrigate the site.

For clinicians who are only rinsing the mouth where there are no open wounds, such as after a recall maintenance procedure, using a disposable syringe and disposable cup filled with common tap water is acceptable. On average, water taken directly from the tap is of better microbiologic quality than water delivered from the three-way syringe and dental unit waterline.

Will an Ultrasonic Scaler Be Used?

If so, there is no way to completely eliminate the dental unit waterline contamination problem. For more than 20 years, dentistry, especially dental hygiene, has placed a great deal of faith in ultrasonic instrumentation that, to date, validated well-controlled clinical research does not support:

* Lack of evidence proving superior results. There are no published, properly controlled clinical studies that demonstrate statistically significant superiority over hand scalers and curettes with respect to: preventing periodontal attachment loss, maintaining periodontal attachment levels, and/or preventing tooth loss in humans; and preventing occupationally related repetitive-stress injuries such as carpal tunnel syndrome.

* Demonstrated occupational health hazard. The aerosol spray associated with using ultrasonic scalers in a typical treatment room setting (dental hygienist performing treatment without a dental assistant operating an independent high-speed evacuation line) exposes the dental hygienist to unacceptable disease transmission risks. See these references:

Journal of the American Dental Association, Vol. 129, September 1998: Aerosol and splatter contamination from the operative site during ultrasonic scaling.

Journal of Periodontology, Vol. 69, No. 4, April 1998: Blood contamination of the aerosols produced by in vivo use of ultrasonic scalers.

Journal of Periodontology, Vol. 75, No. 5, May 1999: Aerosol and splatter production by focused spray and standard ultrasonic inserts.

* Potential Patient Health Hazard. The American Dental Association Council on Scientific Affairs published a report in the November 1999 Journal of the American Dental Association titled "Dental Unit Waterlines: Approaching the Year 2000." The article stated, "The use of instruments such as the ultrasonic scaler, which potentially could force organisms into breaks in the gingiva, may raise the possibility of introducing microorganisms into the bloodstream."

* Relatively high cost. The cost for purchasing and maintaining ultrasonic scaler units and tips is substantially more for the dental practice than the cost associated with utilizing the finest hand instruments.

In 1993, the CDC introduced universal precaution recommendations for infection control practices in dentistry. It recommended that patients always receive sterile output irrigant during any dental surgery. The use of sterile output irrigant for invasive, at-risk procedures has long been the unquestioned standard of care in medicine. The ADA has not adopted this CDC recommendation as a regulatory guideline for routinely performed invasive, at-risk dental procedures.

A Call to Action

With or without regulations requiring dental clinicians to provide specific safeguards, such as sterile output irrigation, patients deserve the safest possible measure of care during invasive, at-risk dental procedures. Dentists -- including all periodontists and all endodontists performing surgery -- who use conventional dental unit waterlines and high-speed drills while performing the invasive, at-risk procedures indicated above could take a leadership position and proactively improve their treatment delivery systems to provide patients with sterile output irrigant.

By taking the initiative, these clinicians would help provide needed support for dentistry’s waterline improvement efforts. In addition, voluntarily acting to improve public safety would further enhance public and media opinion about the progress being made by the dental profession.

Author

George K. Merijohn, DDS, is a periodontist in private practice in San Francisco.

To request a printed copy of this article, please contact: George K. Merijohn, DDS, 450 Sutter St., Suite 2336, San Francisco, CA 94108 or Merijohn@perioaccess.com