In 2700 BC, the Easterners have begun to gargle with saline solution to combat periodontal disease. In modern times, it can be traced back to the Keyes technique, which was widely circulated in the United States in the late 1970s. Water molecules diffuse from microorganisms to the outside world through the principle of osmotic pressure in high-concentration salt solutions, resulting in plasmolysis, thereby sterilizing, or inhibiting bacterial growth. This systematic literature review investigates the effects of saline solution on oral tissues and pathogenic microorganisms, and whether saline solution gargling can inhibit dental plaque or promote wound healing.