Nearly 32 percent of U.S. women aged 65 to 69 years have no teeth. Because some tooth loss may reflect systemic osteoporosis, and because estrogen therapy seems to protect against osteoporosis, the authors examined the risk of tooth loss relation to hormone use in a prospective study of 42,171 postmenopausal women. The risk of tooth loss was lower in women who currently used hormones. Although few studies have examined this issue, this research suggests that estrogen may reduce tooth loss.