Abstract: Objective: To compare the vertical effect between infrazygomatic crest high planting miniscrew combined with horizontal palatal bar and high headgear face-bow combined with horizontal palatal bar in the treatment of hyperdivergent classⅡ protrusion. Methods: Twenty patients with hyperdivergent classⅡ protrusion were randomly divided into two groups with 10 cases in each group. The control group adopted high headgear face-bow + horizontal palatal bar + straight wire technology, and the experimental group adopted infrazygomatic crest high planting miniscrew + horizontal palatal bar + straight wire technology. Maxillary anterior teeth were retracted by sliding method to close the extraction spaces for two groups. Lateral cephalometric films were taken pre and post orthodontic treatments. Vertical parameters of teeth and skeleton were analyzed by measuring the cephalogram pre and post treatments. Results: Statistically significant differences were existed on vertical parameters (SN-MP°, N-Me, N-SGn°, U6M-PP) measurements between two groups or pre and post orthodontic treatments in experimental group. There was no statistically significant difference between all the parameters of the control group and UO-PP of the experimental group pre and post treatments, the anterior teeth were lowered by 0.4mm on average in the experimental group, reversely elongated by 0.5mm on average in the control group, but there was no significant difference between two groups. Conclusion: Infrazygomatic crest high planting miniscrew combined with palatal bar in the treatment of hyperdivergent classⅡ protrusion could depress the maxillary molars, as well as a little press down maxillary anterior teeth, which could gain better effect for vertical skeletal pattern.

Key words: Miniscrew, Face-bow, Hyperdivergent class Ⅱ protrusion