目的分析第二磨牙参与到固定矫治系统中的优缺点及其适应证。方法通过对临床病例的分阶段分析,掌握第二磨牙未参与和有适应证时早期参与到矫治系统的优缺点。结果在第二磨牙未参与矫治系统时有较多并发症,而第二磨牙上带环后可防治此类缺点,第二磨牙早参与到矫治系统中的病例可缩短疗程。结论在直丝弓矫治系统中,第二磨牙尽早上带环进入矫治系统,可缩短疗程。 Objective To analyze the advantages and disadvantages of second molars participating in fixed orthodontic system and its indications. Methods According to the phased analysis of clinical cases, master the advantages and disadvantages of early participation in the orthodontic system when the second molars are not involved and have indications. The results in the second molar did not participate in the correction system when there are more complications, and the second molars with a ring can prevent such shortcomings, the second molar early participation in the correction system can shorten the course of treatment. Conclusion In the straight wire correction system, the second molar as soon as the loop into the orthodontic system, can shorten the course of treatment.