In my career I am continually surprised by the number of people who have never been shown how to floss correctly. While most people do a reasonable job of brushing, flossing is more difficult to do correctly.
Flossing has two main functions. Firstly, to remove food and plaque between the teeth and therefore prevent tooth decay. Secondly, if plaque is removed from underneath the gums, it serves to prevent gum disease. Sadly, the importance of flossing is often forgotten, even by dentists.
Gum disease is a process of inflammation that affects the gums (gingiva) and the periodontal ligament that supports the tooth in the bone. Mild symptoms of gum disease include red, puffy gums that bleed easily. This is called gingivitis. In its most severe cases, gum disease can cause loose teeth, bad breath and even tooth loss. This is termed periodontitis.
Every new patient I see is taught how to floss correctly. Below is a guide from the Australian Dental Association on flossing. (Reproduced with permission)