Abstract: A disposable guard device for removable attachment to a dental cleaning instrument which uses a prophy angle with a spinning prophy cup to polish tooth surfaces. The device is formed of a flexible, resilient material and includes an attachment portion and an integral dome portion. The attachment portion is structured and disposed for removable, snug fitted receipt over the head and neck of the prophy angle to securely hold the dome portion in surrounding relation to the prophy cup, thereby providing a shield that prevents splatter of cleaning paste and bodily fluids when cleaning the teeth of a patient. The wall forming the dome portion is transparent to allow visibility of the prophy cup against the tooth surfaces during cleaning.