Brushing cannot clean between your teeth, but bacteria certainly can live there quite happily, creating enamel-destroying acid 24/7. Rinsing does not remove plaque anywhere, so flossing is a must. Here is an x-ray of a cavity between teeth:
![X-Ray_02-07-13](https://www.cookfamilydds.com/newsite/wp-content/uploads/2013/08/x-ray_02-07-13.jpg)
Smiles,
Dr. Cook