If you ask your dentist for a tooth cleaning , the hygienist will clean your teeth which means you’ll leave the office in good mood, unable to keep your tongue off of your sparkling teeth.
If you ask your dentist for a tooth cleansing, a dentist, or, more likely, an oral surgeon will remove some of your teeth and you will leave the office in pain. And you’ll be in pain for a couple of weeks, unable to keep your tongue off of the new holes in your head. And also unable to keep the part of the movie Poltergeist, when the old woman says this house is cleansed out of your head. Although you’ll likely be thinking, this mouth is cleansed.