I just used crest whitening strips and now my teeth hurt, what could be wrong?

Crest WhiteStrips: It's important that patients see their dentist prior to any whitening procedure to make sure that they have no cavities, defective fillings, erosions, etc. The sensitivity could be something common and temporary merely related to the whitening process or...Due to a dental problem (or both). When was your last dental checkup? Only a dentist who can clinically examine you can determine the cause.