How to prevent splatter during polishing using Lotus splatter guard prophy angle

The current generation of prophy angles are designed like cars before 1902 when there was no windshield wiper on a car.  This required drivers to keep on stopping during snow, and then get out and clean snow from the windshield.  Exact same situation exists in today’s prophy angles where hygienist must stop the procedure and wipe the splatter off the cup and then continue with the polishing procedure.  This happens due to lack of a splatter guard on a prophy angle.  LOTUS splatter guard prophy angle address this long-standing issue by incorporating splatter guard on the prophy angle.

The easiest way to understand why splatter happens during polishing is to look at how an ice skater increases and decreases rotational speed. An ice skater controls angular momentum by bringing the arms closer to her body to increase the speed and decreases speed by moving arms outward.

The position of the skater’s arms affects the Momentum of Inertia. When the mass (the arms) is away from the axis of rotation (the midline of the skater’s body), the moment of inertia increases, when the mass is closer to the axis, the moment of inertia decreases.  Therefore, when the skater tucks her arms in, the moment of inertia decreases, and angular velocity increases, helping the skater spin faster.

Exact same thing happens as the slurry moves from flared portion (equivalent of arms out = largest diameter) to non-flared portion of the cup (smallest diameter) where it gains speed and has a chance of flying off the cup. The saliva, paste and blood mixture will fly off as the diameter decreases as the rotational inertia of the mixture goes down and mixture rotates faster.  Hence, here one needs to have a splatter guard in approximately upper ¾ region of the cup where cup tends to become narrower as one moves away from the tooth surface.

But before the splatter can be removed, it is important that the saliva be retained on the flared portion of the cup.  This is achieved by having dimpled geometry on the exterior of the cup that that keeps the saliva attached to the outside of the cup by increasing surface area and creating a thin, turbulent boundary layer that keeps the saliva attached.  This situation is equivalent to what happens to a golf ball when it travels through air. Once saliva rides up on the cup away from the tooth surface, the saliva is removed by using splatter guard.

The design was validated using CFD analysis by counting no of particles that passed though the screen.  Three scenarios were analyzed (smooth cup, cup with dimpled geometry and prophy angle with a splatter guard).

1) Reference Geometry: Standard Smooth Cup

2) Cup with Dimpled Geometry

Presence of dimples alone resulted in 58% splatter reduction

3) Dimpled Cup with a Splatter Guard

To effectively control splatter during polishing, the prophy angle needs to have a cup with dimpled geometry to retain splatter on the flared portion and a flexible splatter guard to wipe the splatter.

You won’t drive your car in a rain without wipers so why polish without a splatter guard?