1. Poor oral hygiene: Not brushing and flossing regularly can lead to the buildup of plaque and bacteria on the teeth and gums, causing gingivitis. 2. Plaque buildup: When plaque is not removed from the teeth, it hardens into tartar, which irritates the gums and leads to gingivitis. 3. Hormonal changes: Hormonal fluctuations during puberty, pregnancy, and menopause can make the gums more sensitive and prone to inflammation. 4. Smoking and tobacco use: Tobacco products can irritate the gums and reduce blood flow, making it easier for gingivitis to develop. 5. Certain medications: Some medications, such as anticonvulsants and immunosuppressants, can cause gingival overgrowth and increase the risk of gingivitis. 6. Systemic diseases: Conditions like diabetes, HIV/AIDS, and leukemia weaken the immune system, making it harder for the body to fight off infections, including gum infections like gingivitis.