You will probably find major differences of opinion when it comes to teeth whitening for children. Thousands of whitening studies have been performed over the last couple of decades. These studies have one conclusion in common. Professional whitening (when performed using ADA/FDA-approved professional systems under the supervision of a dentist -- and using the system just as directed) will not damage healthy permanent teeth. This means that children (who have their permanent teeth) CAN safely whiten their teeth. The clinical answer is just that simple.
However, this topic certainly opens the floor for discussion regarding the social, psychological, and emotional aspects of the subject of teeth whitening in children. From one standpoint, why should a 12 year-old child be thinking about cosmetic enhancements at such a young age? On the other hand, will the child with dark yellow teeth be teased ("butter teeth, dirty teeth”) to the point that the child learns to stop smiling, laughing -- or starts covering his or her mouth with every laugh? What about the child who has average teeth, but whose mom thinks the teeth need to be whiter? Many times, parents get nervous when the first permanent teeth start to grow in because they are so much darker in color than the baby teeth. (Remember, we used to call baby teeth "milk teeth" because they are so very white in color. So, when the permanent teeth start growing in amidst the milk teeth, they will look much darker in contrast.) There are so many different situations within this topic, that I believe it's impossible (and irresponsible) to have one answer across the board.
When I have a young patient (under 17 years-old) who wants whiter teeth, I first talk with the child and his or her mom or dad. We discuss the "whys" behind the desire to whiten the teeth. If is a situation like the aforementioned one (permanent teeth look dark growing in next to baby teeth), then we opt to wait until all of the permanent teeth are in and revisit the topic if needed in the future. If it's a kid who is handicapped by the appearance of his or her smile, then yes, I absolutely agree with whitening teeth to improve confidence (we've been straightening teeth with braces for this reason for decades). If I'm dealing with an over-obsessive parent, I try to find out if whitening is something the child really wants. If it's not something the child wants, I tell them to wait until they really want to whiten.
When we decide it's in the best interest of the child to do some whitening, then we customize the treatment based on the different needs of each patient (just like we do in adults). The safe professional methods available are the same as those available to adults (custom trays, professional strips, and in-office whitening).
When it comes to teeth whitening in children, the clinical methods are no different than they are in adults. However, before agreeing to do the procedure, it is important to take the time in consultation to address the "whys" behind the treatment.