Objecitve To discuss the relationship between peridontopathy and estrogen. Method We discussed the relationship between periodontopathy and increasing of estrogen, the relationship between peridontopoathy and deficiency of estrogen and the relationship between osteoprotegerin in osteoblasts and estrogen. Results When estrogen increased or decreased abnormally, osteoporosis could occur, which induced alveolar ridge resorption and alveolar bone atrophy. Then the teeth exfoliated.Teeth uncleanness facilitated periodontopathy. Conclusion No matter how young or old, keeping the relative balance of estrogen can protect gingiva and alveolar bone. At the same time, keeping teeth clean is also essential to prevent periodontopathy.