As the unavoidable concurrent disease in orthodontic treatment, root resorption has captured the attention of orthodontists. The parathyroid hormone（PTH） and parathyroid hormone related protein（PTHrP） have been used in orthodontic treatment by scholars in order to find the mechanism of tooth resorption and tooth repair which are complicated. This paper reviews the basic effect of PTH and PTHrP, also summarizes the machnism of PTH and PTHrP affect the cementoblast, alveolar bone cells and periodontal ligament cells.
