Over the counter home teeth whitening trays, despite the disapproval of the American Dental Association (who, a cynic might complain, are merely protecting their own), are not without their advantages either. They cost a lot less, for one thing, since you are supplying your own parts and labor, rather than relying on someone else to whiten your teeth for you. Also, because they use a lower concentration of peroxide in the gel, there is less risk of irritation to the teeth and gums.
Another advantage of over the counter home teeth whitening trays is that you get to keep the trays. This means that if you want to use them again, for a retouch later on you don't have to go back to the dentist for another fitting.
Of course, the use of any home teeth whitening kit requires a certain amount of self-discipline. However, given sufficient willpower, there is no reason why you shouldn't achieve exactly the same results with an over the counter home teeth whitening kit as you would with one supplied by your dentist. In the words of Yoda: "Control, control, you must learn control".