It depends on what level of gum disease your father has, but definitely try to find ways to remind him to brush his teeth. It is recommended that you take your father to the dentist and have his oral health evaluated. Gingivitis is the beginning stage of gum disease and symptoms include red, swollen, and bleeding gums. That can be reversed with proper oral hygiene if you can get him back on schedule. A more extreme case, periodontitis, could lead to infection in his mouth. If he’s at that stage, he may need a deep cleaning or oral surgery.