There are basically two types of handpieces, air-driven and electric. Electric handpieces are much stronger than air-driven due to the fact that a motor is spinning the bur as opposed to air. This allows the doctor to remove decay at a faster pace. This will cut down on the time it takes to complete a procedure. However, the biggest benefit to the patient is how silent the handpieces are.
There is virtually no loud whistle that adds to the overall comfort of the patient.