There are a number of reasons why people may develop sensitivity of their teeth and gums; namely receding gums and gum disease, problems with the roots of their teeth or damage to the enamel covering. Tooth sensitively can sometimes develop after dental treatment and in particular after tooth whitening. Thankfully there are now gum treatments and remineralising products which can help improve this sensitivity.
Using a specially formulated toothpaste can help reduce the sensitivity.