Hazardous Aerosols Challenge the Dental Industry

Hazardous Aerosols Challenge the Dental Industry

By Susan English

The profession of dentistry lags an astonishing 30 to 50 years behind other industries that employ scientific aerosol instrumentation, such as the semiconductor, pharmaceutical, food-processing, biotech and medical industries. According to one expert: “dentistry went along with virtually no controls since its inception, and now all of a sudden, they (dentists) find themselves having to comply with some government regulations, which in my opinion are very basic and nothing to be excited about…But they`re coming from `nowhere,` so I think there`s a feeling of, `Let`s get`em up on the basics, and then go back and look at the air question.` “

OSHA-mandated “General Procedures,” which protect dental workers, are evident to every nervous occupant of a dental chair: hand-washing, mask coverage of eyes, nose and mouth, protective apparel, the use of efficacious disinfectants, and the sterilizing of instruments. Such barriers afford dental professionals some protection from “splash and splatter,” but they do not begin to address aerosol contamination–the invisible and more widespread microbials and dental filling materials generated by today`s high-speed dental handpieces. Then there are volatile chemicals such as formaldehyde and methyl methacrylate and those found in disinfectants, cleaning agents and photographic chemicals.

This is the assessment of clinicians, researchers, microbiologists, university dental school faculty and general practitioners on the cutting-edge of the dental profession. Perhaps the main spokesperson for bringing the “bad news” about aersolization to the dental profession is T.C. Webber, a medical and industrial microbiologist whose firm, Luxor, (Palo Alto, CA) specializes in aerosol research. He says that the FDA is now giving attention to the volatility of such chemicals, but only in very low concentrations. But the FDA is not paying attention to microparticulates generated by the use of the dental handpiece, ultrasonic scalers, cauteries and lasers that may also act in this fashion. Webber, who presented a paper on “Cleanroom Applications for Hazardous Dental Aerosols” at CleanRooms West `93, contends that the profession`s research so far has not been based on scientific aerosol methodologies, but on routine laboratory experimental trials, which cannot size and count aerosolized submicron particulates in a specific volume of air, as detected by a laser particle counter. Webber, who continues to address many dental and related industry organizations on the subject, advocates the use of recirculating HEPA and carbon-sorbent filters installed overhead in ceiling tiles.

T.C. Webber is not alone in his concerns about the lack of research and awareness of aerosol contamination in dentistry. Drs. Rella and Gordon Christensen founded Clinical Research Associates (CRA) in 1976 as a unique, volunteer research center located in Provo, UT, to pursue basic research and conduct controlled clinical studies of dental procedures and practices. Conceived of as a sort of “Consumer Reports” of the dental industry, CRA plans to undertake its own aerosol research effort in 1996. It will be an effort to characterize dental operatory air, looking at types of particles, particle size, how long it takes for particles to settle, and whether they are pathogenic. As to the use of “cleanroom technology,” Dr. Rella Christensen says she doesn`t know of any dentists who are using HEPA filtration or chemical hoods in their operatories, although there are some smaller air purification systems, similar to home air filtration systems, being used for odor control or control of hypersensitivity compounds. “There was a lot of flurry and research…back in 1959-61, as high-speed air rotor handpieces were introduced into dentistry, especially when it was found that microbial aerosols were generated by the new handpiece. But that all kind of quieted down about mid-1960, and it really hasn`t come up again,” she says.

Another approach to air quality in dental offices is taken by Dr. John Young, a clinical professor and director of research in the Department of General Dentistry at the University of Texas Health Science Center`s Dental School in San Antonio. He worked extensively with NASA since the 1960s to develop specialized instrumentation and treatment protocols for space missions, notably the design and construction of the dental/medical treatment equipment for Skylab, the International Space Station, deep space missions, and colonization of the moon. He designed a treatment system that minimizes aerosol spread throughout a space cabin.

Dr. Young advocates the use of laminar air flow in today`s dental offices, and he has taken some of this unique spacecraft technology and applied it in dental offices here on earth. He has constructed a laminar-flow dental treatment system designed with air flowing in over the head of the chair from the ceiling and exhausted toward the foot of the chair at baseboard level. His designs are being used in the construction of San Antonio`s public clinics and also at a clinic on the Mille Lacs Indian reservation in Brainerd, MN and numerous private and commercial clinics throughout the world. His “Dental Treatment Room Design Laminar Air” guidelines outline air flow entering through ceiling vents into the central air return system. Bringing a self-contained laminar air system right to the patient, as is done in NASA`s designs, would not be practical, he says, because of the limited treatment space in most dental offices. His solution is to exhaust aerosol-laden air at baseboard level away from the patient and staff.

Dr. John Young says: “One of the problems we have is that the dental mind thinks that if you can suck it into a vent somewhere, you can forget it! The fact that contaminated air just gets recirculated doesn`t occur to them. If we`re going to suck pathogens out of the room and then distribute them to the receptionist and the rest of the office, that`s no good. We have to think beyond just the room itself and look at the entire system.”

Dr. John Molinari concludes: “I think dentistry has come a long way. Where you`re looking at air recirculation, you have a major problem in that you`re not dealing with regional centers like hospitals or even nursing homes: you`re dealing with independent, cottage-industry type healthcare offices. And you can go from A to&#165as to air recirculation systems. Do you need positive or negative pressure? I don`t know, because people still don`t have the data, and some of the data can take 20 years to develop, because it takes that long for the body to react to some things.”

One of the problems cited by dental clinicians is the extreme reluctance on the part of dentists themselves to tolerate more regulation. T.C. Webber maintains that dentists are overloaded with the wrong kind of regulation. “It`s not `more handwashing` that is needed to control aerosol contamination, but real scientific aerosol research and accurate measurement of levels of aerosol contamination with aerosol instruments and controls”–the kind that already exist in cleanroom and clean manufacturing technology. n


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