The Wand is essentially a computer controlled dental injection device. The flow rate of the local anesthetic is controlled by a computer. This means that the injection is guaranteed to be slow and steady and therefore comfortable.
Most people who have had a bad experience with injections think that the needle stings because the skin is pierced, but this is not so. Most often, the sting was caused because the anesthetic was fired in too quickly. The idea of the Wand is to take out the human error. This can be very reassuring for people with previous bad experiences.