The next time you unscrew the cap from your tube of toothpaste, take a look at the threads. They are quite likely Buttress threads. Have you used an adjustable wrench lately? Look at the thumb-screw. Buttress! All this time, right under your nose, was a thread-form that most people think, or know very little about.
Synonyms for "buttress" include; strengthen, reinforce, fortify, and support. The unique geometry of a buttress thread-form fulfills that requirement.
This thread-form is designed to stand up to a heavy axial load in one direction. This enables the thread to