Each tooth is like a box; they have 5 surfaces that require cleaning. By using a toothbrush, you are cleaning the top, front and back surfaces, but due to the diameter of the bristles, they are unable to access between the teeth. That means that if you are brushing your teeth but not using an interdental aid such as floss, you are missing nearly half the surfaces in your mouth! Bacteria are constantly forming on your tooth surfaces and even underneath your gums, and the same is true for between your teeth. 

Gingivitis, which is inflammation of the gums from the presence of oral bacteria, is thought to affect up to 90% of the population in varying severity. Gingivitis can lead to gum disease, bleeding gums, tooth sensitivity and even loose teeth. Gingivitis can occur localized or generalized, and therefore it is important to clean all tooth surfaces to prevent it.