Model 3 demonstrated that, after adjusted for sex, age, education year, living alone, BMI, cigarette smoking, alcohol drinking, anxiety, depression, heart disease, hypertension, diabetes, and APOE-ε4, tooth loss of >16 were significantly associated with dementia with an OR of 1.56 (95%CI 1.12–2.18). The gene discussed is APOE; the disease is major depressive disorder.