>>11608570When you have any amount of bacteria on your teeth, they form biofilms. When those biofilms become thicker, it's called plaque. When that plaque starts to leech minerals from your spit and hardens, it's dental calculus.
Every step of that process is able to be removed with abrasion except for calculus. You brush your teeth every day so that soft plaque is removed before it hardens into calculus. When dentists are scraping your teeth with their fancy sharp instruments, what they're really doing is rubbing away the calculus, which has a rough texture that makes it stupid-easy for more bacteria to invade and cause cavities.
