Why do the peroxide bleaching agents found in tooth whitening products cause tooth sensitivity?

The breakdown of the peroxide in whitening products expands dentinal tubules, increasing the pulp’s sensitivity to hot and cold stimuli such as food and beverages. Potential sources include exposure of the tooth to elevated temperature for an extended period of time (activation lights) during bleaching, dehydration of the tooth and the penetration of the peroxide bleaching agent into the nerve tissue.