Opalescence PF 35% Mint Teeth Whitening 8 Pack

I have used the 20% several times before with excellent results.With the 20%, you have to leave the trays in much longer.However, you will achieve the same whitening effect with either product.The 35% is MUCH stronger.Should you forget to take the 35% trays out on time (even ten minutes too long), you will regret it.Tooth and gum sensitivy will be quite noticable.With the the 20% solution, should you forget to take the trays out on time (even an hour or two), the resultant tooth and gum sensitivity will be far less.The 35% solution is a great produt, just keep your eye on the clock and follow the directions.

As always, great shipping and prices with Amazon.I checked several sites, and Amazon had the best overall offer.