Bests & Worsts Reviews from Amazon

Like many of the reviewers, I was concerned by the apparent lack of the expiration date on the product packaging. Was I wasting hours wearing the trays with the product that may have expired ? Well, there's an expiration date after all, except it's not very obvious. I dug up some info on Ultradent's website for another product line they have on the convention they use (and I'm presuming it is consistent across their product lines). The expiration date is indicated as "ZMMY", where Z is a product lot letter, MM is the month and Y is the year. For example, A055 would mean an expiration date of May 2015. So look closely on your syringe for these characters. Also, for those who complained about the lack of instructions, well- they're right on Ultradent's website (a whole PDF file of instructions, in fact). ultradent.com/en-us/Product Instruction Documents/Opalescence Tooth Whitening.pdf In particular, it says- "Wear Opalescence 10% for 8-10 hours or overnight, Opalescence 15% for 4-6 hours, Opalescence 20% for 2-4 hours, and Opalescence 35% for 30 minutes." So keep on smiling with your (hopefully brighter) smiles !