Pre-procedural rinse: one minute that changes the aerosol load for the hour that follows

Ultrasonic scaling and air polishing are among the procedures that generate the most aerosol in dentistry, and the hygiene appointment contains both.

The aerosol produced is not just coolant water: it carries saliva, blood, biofilm dislodged from the surfaces, and material from the gingival sulcus.

It should be separated into two components that behave differently. Larger droplets fall quickly and contaminate the surfaces near the chair; fine particles stay suspended in the air for far longer.

The distinction is practical rather than academic: surfaces are contaminated immediately, the air stays loaded after the appointment has ended, and this determines what to do and in which order.

The pre-procedural rinse acts on one specific point: it lowers the bacterial load of saliva at the moment the aerosol is generated. It sterilises nothing, it reduces the starting inoculum.

The agents studied are chlorhexidine at 0.12 or 0.2 per cent, cetylpyridinium chloride, hydrogen peroxide at 1 per cent, and essential oil formulations. Chlorhexidine has the broadest literature behind it.

What separates them is substantivity, meaning the ability to bind to oral surfaces and keep working. Chlorhexidine has a great deal of it, peroxide essentially none: it works in the moment and stops there.

One point deserves to be stated honestly, because it is often left out: the available evidence concerns the reduction of microbial counts in the aerosol, not a demonstrated reduction in infections among operators. It is a reasonable measure at negligible cost, not a proven protection.

High-volume evacuation remains the most effective intervention against dispersion, because it intercepts droplets at the point where they form. Rinse and suction are complementary rather than alternative: the first lowers the concentration, the second reduces how much of it escapes.

The most common sequencing error between patients is disinfecting surfaces immediately after the appointment. It looks diligent, and instead it means cleaning while the fine component of the aerosol is still settling.

The correct order allows time for the air to change over first, then disinfects the surfaces. How much time is needed depends on the room's air exchange rate, which in many practices is the least known and least controlled variable.

In practical terms, the patient should be instructed to rinse for the time stated by the product rather than the three seconds they will do spontaneously, because a rinse that is too brief reduces the effect to little more than a symbolic gesture.

In summary: aerosol contains saliva and biofilm as well as water, large droplets soil surfaces while fine ones stay airborne, the pre-procedural rinse lowers the starting inoculum without sterilising, the evidence concerns microbial counts rather than operator infections, and disinfecting before the air has changed over wastes part of the work.