Chris Miller, PHD
This is the third article in a series discussing the routes by which microbes are spread in the office. The first two articles discussed patient to dental-team spread and dental team-to-patient spread. The three remaining pathways are:
(1) Patient to patient
(2) Office to community
(3) Community to office
This discussion involves patient-to-patient spread.
Pathways that allow microbes from one patient to spread to another patient involve contamination of hands, inanimate objects or operatory surfaces that will be used in the treatment of subsequent patients. Improper use of barriers may contribute to this type of spread. In fact, one of the most clearly documented cases of disease spread in a dental office involved patient to patient spread of microbes on the hands of a hygienist (Manzella et al., J Amer Med Assoc 1984; 252:2219-2022).
A hygienist who did not routinely glove had dermatitis on her hands and fingers. She treated a patient with active herpes labialis and the virus contaminated her hands. The pain from her dermatitis prevented her from thoroughly washing her hands, so the virus persisted on the skin. This dermatitis also provided additional places on the hands for the virus to "hide out." About a week later vesicles cropped up on her hands. However, before these symptoms appeared she already had treated several patients. In fact, 20 of these patients developed intraoral herpes. At the onset of her symptoms, she began wearing gloves, which prevented further spread.
This case points up several important aspects of infection control. Gloving clearly can protect patients as well as members of the dental team. Handwashing can help protect both the dental team and patients and it can be compromised by painful dermatitis. Finally, it`s not a good idea to treat patients with active herpes oral or perioral lesions.
Although this case is used to demonstrate the pathway of patient-to-patient spread, it involves two other pathways already discussed. Since the hygienist`s hands became infected, patient-to-dental team spread occurred, and since subsequent patients became infected, dental team-to-patient spread occurred.
Other improper use of barriers also may result in the spread of microbes from one patient to the next. The outside of the facemask becomes contaminated from spatter. If this mask is not changed for the next patient, and it is touched during treatment, patient-to-mask-to-hands (gloves)-to-patient spread may occur. A similar situation may occur if protective eyeglasses are not cleaned between patients and subsequently touched during treatment of the next patient.
While there are no documented cases of disease spread from contaminated dental office surfaces, it is obvious that operatory surfaces do become contaminated with patient microbes during treatment sessions. This contamination occurs by three routes:
(1) Spatter from the patient`s mouth reaching a nearby operatory surface
(2) Dental team`s contaminated hands touching operatory surfaces
(3) Contaminated instruments or supplies contacting operatory surfaces
Prevention of spread from patient to operatory surface to patient involves two approaches:
(1) Clean and disinfect the contaminated surface before the surface is involved in subsequent patient treatment, or
(2) Cover the surface with a fluid-proof cover to prevent the surface from becoming contaminated and then changing the cover before treatment of a subsequent patient.
Another potential route for spread of microbes from one patient to another involves hand instruments and handpieces or any other reusable item used intraorally. These items must be managed properly because they have direct contact with patients` tissue.
Contaminated instruments and handpieces must be cleaned, packaged, and sterilized before reuse to prevent patient-to-patient spread of microbes.
Cross-contamination from one patient to the next can occur if clean or sterile supply items or instruments are contaminated before they are used. One way this may occur is the use of unpackaged instruments. Such instruments may be recontaminated if improperly touched before reuse. For example, several unpackaged instruments stored in a drawer at chairside may be contaminated with "saliva-coated fingers" when removing just one instrument unless an aseptic retrieval method is used. The same applies to bulk supply items at chairside. If cotton rolls, for example, are stored in a container at chairside, several may be contaminated when retrieving one unless sterile cotton pliers rather than "saliva-coated fingers" are used for retrieval.
Patient-to-patient spread of microbes also may occur if items that are normally disposable are reused on another patient. Disposable items are not intended to be cleaned, let alone sterilized.
For example, plastic disposable air/water syringe tips and high-volume evacuator tips resist cleaning because microbes can hide in the scratches made in this "soft" plastic.
Chris Miller is director of Infection Control Research and Services and professor of oral biology at Indiana University.
Patient-to-patient spread of microbes may occur from:
* improper use of barriers
* inadequate handwashing
* poor management of operatory surfaces
* inadequate cleaning or sterilizing of instruments and handpieces
* contamination of bulk supplies
* lack of aseptic retrieval systems at chairside
* recontamination of processed instruments before use
* reuse of disposable items.