When asked this by one of my patients, usually it means that they have not been brushing and flossing correctly and have gum inflammation. To insure healthier gums, I ask them to brush twice a day for two minutes and clean between their teeth with either floss,proxabrush or stimudents. I often recommend using a good electric tooth brush, such as a Braun Oral B electric toothbrush. The good news is often the bleeding goes away after a patient has had a cleaning and starts an improved oral hygiene regime at home.
Getting a regular prophylaxis at the dentist definitely helps reduce gingival inflammation and also gives your dental team an opportunity to give some tips on you might to do a better job at home . It is always a good idea for a patient to demonstrate their brushing and flossing techniques for their dental hygienist or dentist. Afterwards we can see what changes you might try to improve your results.