0.05). Conclusion: The measurements of molar distal movement on model are smilar to those on cephalometric radiograph.

Objective: To evaluate the effect of a new method to treat early primary crossbite . Methods: 20 cases (2.8～6.5 years old ) with anterior crossbite were treated by bonding appliance combined with protracting mask. Cephalometric radiographs were taken and analyzed before and after treatment. Results: On average,in all the 20 cases the maxilla were moved 2.06 mm forward ,mandibular were turned 2.45?downward and backward ,the anterior crossbite was corrected and the face profile was improved satisfactorily.The treatment was conducted for 1.7 months on average. Conclusion: Using bonding appliance combined with protracting mask to treat early primary crossbite can achieve good effects for young children .

objective: To evaluate the effect of Quad Helix appliance in expanding narrow dental arch. Methods: 12 cases were treated by Quad Helix appliance. The effect was evaluated by measurement of the dental arch. Results: The dental arch of all the patients was expanded in half a year.The width between the maxillary first molars increased by 8.95 mm, and the width between maxillary first premolars increased by 5.7 mm. The average time of expanding was 20.75 weeks, the expanding efficiency was 0.43 mm per week. Conclusion: Quad Helix is an effective orthodontic appliance for correction of narrow dental arch.

0.05). The pressure on the first molar from cheek was higher than that from tongue( P

0.05). Conclusion: The tongue measurement with ultrasonic imaging is reproducible.

Objective To explore whether there is any abnormality in the tongue position of the open bite. Methods Tongue position was defined as the relative position of its body in the oral proper cavity on profile cephalometric roentgenogram which was enhanced by the iodine oil applied to the tongue surface. The tongue position was compared between open bite group and normal bite group with student's t test to determine the variation of open bite. Results Compared to the normal bite group, the root of tongue was closer to the uvula in the open bite group, and the distance between the dorsum of tongue and the surface of palate was decreased as well as the tip of tongue was nearer to the incisors. Conclusion The open bite's tongue position is characterized by more upward and more forward and this position may be one of the causes of open bite.

0.05). At stage 2 to 3, the changes of point A was the greatest. Conclusion: Timing of headgear treatment based on the morphological variation of cervical vertebra can obtain the maximum desirable orthopedic effect.

Objective: To study the treatment methodology of postoperative disostosis of maxilla in the patients with cleft palate by orthognathia. Methods: 10 cases (6 males and 4 females) of postoperative dysostois of maxilla in the patients with cleft palate were treated by orthognathia. Operation manners and orthodontic treatment were determined by orthodontists and surgeons before treatment. Orthodontic treatment included upper arch expansion, teeth alignment, leveling the Spee's curve etc. Operation on single jaw or double jaw, or extraction of one anterior tooth to decrease lower dlental arch and to coordinate with the upper jaw forward was conducted according to individual situations. Adjustment of intercuspids relation was conducted after operation. Results: In all the 10 cases discrepancy of upper and lower jaws were resolved, profiles of the faces were improved significantly, dental arch symmetry, physiological overjet and overbite were achieved. Conclusion: Orthognathia is effective in the treatment of postoperative dysostosis in the patients with cleft palate.

Objective: To examine the skeletal factors of Angle's classⅡdivision 1 malocclusion in order to find a reasonable treatment protocol. Methods: The skeletal factors were measured and compared between 86 cases aged 12～25 years with AngleⅡ 1 malocclusion and 86 cases at the same age with normal occlusion. Thirteen measurements were chosen on lateral cephalometric radiograph for the comparison. Results: In the group of maloculsion, some measurements standing for sagittal skeletal pattern were statistically defferent from those in the group of normal occlusion, such as decreased SNB angle and SL linear and increased ANB angle, whereas some were not significently different, such as the SNA angle and PNS-ANS linear; some measurements standing for the vertical skeletal pattern were statistically defferent, such as decreased UM-PP linear and LM-MP linear and increased UI-PP linear, whereas some were not significently different, such as LI-PP linear;some measurements standing for growth pattern of mandibular were statistically defferent, such as decreased SN-MP angle. Conclusion: There are posterior alveolar defficency and mandibular retroposition as well as counterclockwise rotation of mandile in the patients with Angle class Ⅱ 1 malocclusion. The treatment for Angle Ⅱ 1 malocclusion should be to make mandibular move forward and downward in accordance with the characteristic skeletal pattern.

Objective:To investigate the third molar horizontal and vertical drift automatically after the second molar extraction.Methods: 26 patients,aged 11～18 years old, with the indications of second morlar extraction were divided into two groups:15 cases in experimental group with the extraction of the second molar and 11 in control group without the extraction. A cephalometric radiograph of each patient was traced on before and 9 months after treatment. Vertical and horizontal drift and mesio- angulation of the third molar were measured.Results:The third molar vertical mesio-movement (mm)in experimental and control groups was 7.08?2.04 and 2.09?0.47(P