What is the proper noun of toothpaste?

There is no proper noun for toothpaste. "Toothpaste" is a common noun, referring to a general category of products.

However, there are many brand names for toothpaste, which are proper nouns. Examples include:

* Crest

* Colgate

* Sensodyne

* Aquafresh

* Tom's of Maine

Let me know if you have any other questions!