Objective To evaluate the effects of modified Forsus appliance in the treatment of Class Ⅱ mandibular retrusion. Methods 18 children with mandibular retrusion were selected and treated with modified Forsus appliance. Cephalometric radiographs were taken and analyzed at pre-treatment and post-treatment. Students′ t-test was used to determine if there were significant differences between pre-treatment and post-treatment. Results After 6-8 months of therapy, profiles were obviously improved. B moved forward（2.9±3.1）mm. ANB decreased（2.5±1.2）°. The overjet decreased（5.0+2.8） mm. The molar relationship was corrected to Class Ⅰ from ClassⅡ. SN-OL increased（4.3+2.2）°. There was significant difference between pre-treatment and post-treatment. Conclusion Combined with straight wire appliance, modified Forsus appliance can effectively stimulate the mandibular growth, balance the jaw relationship, and correct mandibular retrusion.
