Periodontitis, or gum disease, is caused by plaque buildup due to poor oral hygiene habits like inadequate brushing and flossing. It damages the soft tissue and bone supporting teeth, potentially leading to tooth loosening or loss. Common symptoms include bleeding gums, bad breath, and swollen gums. Diagnosis involves dental exams and X-rays to check for bone loss. Treatment depends on severity but may include nonsurgical procedures like scaling and root planing or surgical options like grafts or bone grafting. Maintaining good oral hygiene can prevent gum disease.