Objective To assess the orthodontic treatment complexity, degree of improvement and objective treatment need of patients by using the index of complexity, outcome and need（ICON）. Methods 114 cases were randomly selected from Hospital of Stomatology, Shandong University. The ICON was used to assess the pre-treatment study models for orthodontic treatment need and complexity for the cases. 20 pairs pre- and post-treatment study models were randomly selected. The ICON was used to assess the pre - and post -treatment study models for orthodontic treatment outcome and treatment improvement. Results In treatment complexity, there were 13（11.4％） cases was easy, 26（22.8％） cases was mild, 21（18.4％） cases was moderate, 29（25.4％） cases was difficult, 25 （22.0%） cases was very difficult in 114 cases. There were 33（28.9％） cases did not need treatment, while 81 （71.1％） cases needed treatment in 114 cases. In treatment outcome, there were 15（75.0%） cases had“greatly improved”, 4（20.0%） cases had“substantially improved”, 1（5.0%） case had“moderately improved”, while there was no patient had“minimally improved”and“not improved or worse”. Conclusion Most patients were difficult to orthodontic treatment. There were partly over -treatment patients. The orthodontic treatment outcome of most patients were satisfied.
