i have tried many different products including that from the dentist which cost in excess of $200 and found this whitener to be as effective as any.if you have very sensitive teeth i suggest you first dont leave it in your mouth for long because it does cause sensitivity.to me it's worth a little discomfort for the results but i am not super sensitive and the whitener from the dentist actually bothered my gums and teeth a little more.for people like me who have a "dead" tooth that darkens in time reguardless of hygeine this is a great answer.occassionally i have to bleach just to keep everything uniform and who doesn't like a brighter smile.as a summary,this is an effective product at a good price that does eactly what it is intended to do.