Going to the dentist should be a relatively simply affair for Derpy. It should contain things like dental floss, mirrors, drills, and all around general well-being of the oral cavity. It should not contain a whole lot of words, particular if those kinds of words aren't the most appropriate things to be saying when you've got your hooves in another one's mouth.

Special thanks to Setokaiva for proofreading. Turns out that is as half important as I thought it would be.