Polymers May Increase Safety in Ultrasonic Use

In the midst of the pandemic, dental hygienists are forced to grapple with a dilemma: either return to hand instrumentation only, which can take a toll on their musculoskeletal health, or continue to use ultrasonics, which is known to aerosolize fluids, including the virus.

Highly transmissible viruses, such as SARS-CoV-2, are spread via visible droplets or aerosols, composed of nearly invisible drops. High-speed dental handpieces and ultrasonic scalers are noted sources of aerosolization. To combat the risk, many offices are implementing high-speed evacuation and airflow diversion; additional personal protective equipment and increased disinfection protocols; and rubber dams and preprocedural mouthrinses. But none of these measures can fully eliminate the chance of transmission through dental aerosols. This leaves practitioners and their patients vulnerable.

Because researchers at the University of Illinois at Chicago (UIC) believe that the only way for clinical practices to return to prepandemic operations is for aerosol generation to be controlled, they have come up with a possible remedy.¹ They discovered that when food-grade polymers are added to the water used in vibrating dental tools, aerosolization was completely eliminated, thanks to their viscoelastic properties.

SNAP BACK

The mechanics of this finding involve what’s known as “coil-stretch transition.” Normally, the use of a rapidly vibrating instrument, such as a drill, generates violent explosions of water, which become airborne as a mist of tiny droplets—just the kind of thing viruses use to spread. But it turns out that when a polymer admixture is used, the bursts of fluid are suppressed.

To test their theory, researchers used ultrasonic scalers and dental rotary handpieces with water and, in contrast, with polymer admixtures as irrigants. They found that, instead of being flung into the air as they would with pure water, generated droplets didn’t detach with the polymer admixtures. They instead formed snakelike threads, thanks to polymer macromolecules. These stretch, similar to rubber bands, only to snap back toward the tips of the tools.

POLYMERS IN THE MIX

Two United States Food and Drug Administration-approved, high molecular weight polymers typically used in food, dentifrice, and artificial salivas were used for the study: polyacrylic acid and xanthan gum. Both were diluted into aqueous solutions and used in instrumentation instead of pure water. Researchers reported the result as complete suppression of aerosolization on a magnetostrictive scaler when used in a demonstration at the UIC dental clinic during supra- and subgingival calculus removal.

The polymers are said to alter the physicochemical properties of irrigation solutions, suppressing the formation of droplets without changing flow behavior in dental unit supply lines. Among their advantages are established biocompatibility, relative low cost, and, as known agents, reduced regulatory hurdles.

With the use of polymer admixtures to eliminate aerosolization of potentially infectious droplets that result from dental procedures, the only infection concerns in dental offices will come from speaking, coughing, and sneezing.

Reference

1. Plog J, Jingwei W, Dias YJ, Mashayek F, Cooper LF, Yarin AL. Reopening dentistry after COVID-19: Complete suppression of aerosolization in dental procedures by viscoelastic Medusa Gorgo. Phys Fluids. 2020;32:083111.