The presents of nutrients, soft tissue and secretions make the mouth a favorite habitat for a great variety of bacteria. At birth, the oral cavity is composed solely of the soft tissue of the lips, cheeks, tongue and palate which are kept moist by the secretions of the salivary glands. The eruption of teeth during the first year leads to the colonization of some bacteria which require a non-epithelial (non-soft) surface and will inhabit this area for as long as teeth remain. The creation of the supporting structure of the teeth increases the habitat for the variety of microbial species.