Which of the following is not an active ingredient in desensitizing toothpaste?

Carbamide peroxide is primarily known for its use in tooth whitening and is not recognized as an active ingredient in desensitizing toothpaste. Desensitizing toothpastes typically contain compounds that help to alleviate dental sensitivity by blocking nerve pathways in the tooth or by creating a protective barrier over sensitive areas.

Potassium nitrate, sodium citrate, and strontium chloride are all effective in the formulation of desensitizing toothpastes. Potassium nitrate acts by calming the nerves within the tooth, which can reduce the sensations of pain associated with sensitivity. Sodium citrate can help in the remineralization process, and strontium chloride also works to block the tubules that lead to the nerve endings within the teeth, providing relief from sensitivity.

Thus, identifying carbamide peroxide as the option that does not contribute to treating tooth sensitivity helps clarify the unique role of various ingredients in dental products.