One of the most common reasons why we have sensitive teeth is we're so used in taking cold drinks with our hot meals. Studies show that when a cold liquid comes into contact with teeth that are hot from food, microscopic fractures in dental enamel can result. Those breaks increase the risk of problems such as tooth sensitivity, cavities, stains, and chipping and breaking of teeth.
It is best to wait at least one minute after enjoying the last hot bite of food before drinking a cold beverage. The teeth are closer to body temperature by that time. :)