An orthodontic system includes a dental appliance (3) and an auxiliary arrangement unit (5). The dental appliance (3) includes a main body (31) defining a receiving space (311) for receiving at least a portion of a dentition (6) of a user therein. The main body (31) is formed with a main projection (33) protecting outwardly away from the receiving space (311). The auxiliary arrangement unit (5) includes an attaching member (51) to be bonded to a tooth (62) of the dentition (6), and a restraining member (52) interconnecting the main projection (33) and the attaching member (51) for moving the tooth (62) toward the main projection (33).
