What causes teeth ache aftering using bleaching trays?

Microscopic answer: Our teeth have tiny fluid filled micro tubules that are normally naturally plugged up. Bleaching unplugs the opening causing sensitivity. Normally the sensitivity goes away with time but it may depend on the specific bleaching product.

Ask your dentist: Some teeth sensitivity is normal during whitening, and should go away shortly. However, if you have cavities or gum recession, whitening gel may cause serious damage. Make sure you do your whitening under your dentist's supervision! goog luck!

Teeth sensitivity : Teeth whitening is a process which opens up the dentinal tubules causing the teeth to become more sensitive. The pain comes as "zingers". As a few days pass the tubules get closed again causing the sensitivity to go away. A desensitizing toothpaste usually helps with post whitening sensitivity. Hope that helps.