Bacteria accumulate in the pocket of your gums, causing your gums to get infected and retreat. The bacteria that form plaque and nestle behind your gums, you get mainly through your food. A gum disease, therefore, develops in the vast majority of cases due to inadequate oral hygiene.
http://scalar.usc.edu/works/dentalhealth/natural-toothpaste-to-regrow-receding-gums