Oral hygiene involves maintaining cleanliness of the mouth to prevent disease spread and increase patient comfort. It refers to caring for teeth, tongue, palate, cheeks and lips to keep them healthy. Poor oral hygiene can lead to issues like bad breath, infections, and gum disease. The purposes of oral hygiene are to prevent infections, keep the mouth fresh, prevent tooth decay and infections, and stimulate salivation and circulation. It should be performed for patients who cannot do it themselves, are unconscious, have local mouth diseases, or are postoperative or on ventilators. Proper techniques include regular brushing, flossing, avoiding sharing brushes, and a balanced diet.