Suppression of cross-infection in actual dental office using viscoelastic polyacrylate solution as a handpiece coolant

In the present work, aqueous solutions of NaPAA [poly (sodium acrylate)] or PAA [polyacrylic acid] are used as the coolants for a dental handpiece to evaluate their suppressive effect on the aerosolization and bacteria (Staphylococcus epidermidis) transmission in an actual dental environment. Both polymer solutions significantly suppressed the formation of aerosols (<50 μm) and droplets (50-100 μm). The suppression effect was stronger at higher concentrations. The 10 and 20 wt. % of viscous Newtonian solutions of low-molecular weight NaPAA were much less effective in disintegration suppression than the viscoelastic 1 and 2 wt. % PAA solutions. The latter was capable of complete suppression of disintegration, forming instead long liquid threads attached to the rotating bur and settling down underneath. The suppression efficiency of the 2 wt. % PAA solution stems from significant elastic forces in it which prevent drop detachment. In the case of water used as a coolant, the bacterial spread was observed through aerosol, droplets, and splatter. The bacterial spread by large splatters was inversely proportional to the distance from the rotating bur. The spread of aerosols significantly occurred in the direction that the handpiece was facing, and multiple airborne aerosols settled on the wall rather than on the floor. On the other hand, the viscoelastic aqueous 2 wt. % PAA solution suppressed bacterial spread, regardless of the distance or direction.