They are checking the health of your gums. When you get older, it's not the cavities that get to your teeth, its the gums that give out and your teeth fall out. Keeping healthy gums by removing food left over in your teeth helps in addition to brushing your gums to massage them. I just had a month long root canal job done because I missed some food caught in the gap between my teeth and it got infected.

Ever seen "Little Shop Of Horrors?" It answers a lot of questions like this about those wild and crazy dentists...

Oh I feel for you. I can't stand that part about the dentist. Bad gums run in my family and I got cursed with them too. My dentist told me that the only way I can prevent serious periodontal disease is to have a cleaning done every four months.

I don't know but they do that to me all the time. They're just not gental and careful enough so when they make you bleed they blame you.

[ORIN] When I was younger, just a bad little kid, My mama noticed funny things I did, Like shootin' puppies with a B B gun I'd poison guppies, and when I was done I'd find a pussycat and bash in its head That's when my mama said [CRYSTAL, RONETTE, CHIFFON] What did she say? [ORIN] She said, "My boy, I think someday You'll find a way To make your natural tendencies pay You'll be a dentist You have a talent for causin' things pain Son, be a dentist People will pay you to be inhumane Your temperament's wrong for the priesthood And teaching would suit you still less Son, be a dentist You'll be a success [CRYSTAL, RONETTE, CHIFFON] Here he is, folks the leader of the plaque! Watch him suck up that gas! Oh, my god! He's a dentist and he'll never ever be any good Who wants their teeth done by the Marquis de Sade? [PATIENT] Oh that hurts! I'm not numb! [ORIN] Oh, shut up. Open wide. here I come! I am your dentist [PATIENT] Goodness gracious! [ORIN] And I enjoy the career that I picked [CRYSTAL, RONETTE, CHIFFON] Really love it [ORIN] I am your dentist [PATIENT] Fitting braces [ORIN] And I get off on the pain I inflict [CRYSTAL, RONETTE, CHIFFON] Really love it [ORIN] I thrill when I drill a bicuspid [CRYSTAL, RONETTE, CHIFFON] Bicuspid [ORIN] It's swell though they tell me I'm maladjusted And though it may cause my patients distress, Somewhere, somewhere in heaven above me I know, I know, that my mama's proud of me Oh, mama 'Cause I'm a dentist and a success Say ah! [PATIENT] Ah! [ORIN] Say ah! [PATIENT] Ah! [ORIN] Say ah! [PATIENT] Ah! [ORIN] Now spit!

Basically, they are trying to see how easily your gums bleed. If they are easy to make bleed, they are not strong enough, damaged, weakened, diseased, or what ever else can possibly make them do so. Not every one bleeds when they do that, but a lot do seeing the majority of people don't brush / floss well.

thats a good question, maybe you need to ask your dentist that question

maybe cause he dont want to admit its his fault

cause they dont want to admit its their fault