If you’ve ever found yourself walking through the aisles of your local drug store trying to pick out which teeth whitening kit works best, you know it’s not the best use of your time or money. In most cases, over-the-counter kits don’t produce the results you want, which means your hard-earned money was put toward an ineffective product. In addition, your wallet may not be the only thing affected, but your smile may be, too! Here are 3 teeth whitening mistakes you should avoid if you don’t want to ruin your smile.