Abstract: Objective: To compare the dentofacial changes produced by refined Sabbagh Universal Spring (SUS2) in late adolescent patients with Class II malocclusion, and quantify them in comparison with patients treated by traditional appliance. Method: The study was carried out on two group Class II patients. McNamara cephalometric analysis was performed on each lateral cephalometric radiograph. Results: The effects of both appliances were dentoalveolar. The refined SUS2 group and traditional group both reduce the distance of A to N-FH, the value is 0.6 and 0.4mm. Lower 1 horizontal to FOP move forward at 0.3 and 1.5mm. As to Lower 1 –Apo, the change of the two group is 0.6 and 2.5mm(P＜0.05) Conclusions: Both appliances corrected Class II discrepancies through dentoalveolar changes; however refined SUS2 appliance can promote mandible forward more early before leveling the teeth as traditional method.

Key words: Sabbagh Universal Spring (SUS2), functional therapy, late adolescence