Human saliva not only lubricates the oral cavity, making possible functions such as swallowing and speaking, but it also helps to maintain integrity of the hard tissues of the teeth. In addition to secretory immunoglobulins saliva contains several less specific antibacterial systems. This innate defense system includes: lysozyme, lactoferrin, peroxidase system, histatins, mucins, and other polypeptides with basic side chains. Some proteins of innate defense system have bactericidal or bacteriostatic effects; some can cause aggregation of oral bacteria resulting in their increased clearance from oral cavity.