The Clinical Investigation Of The Distal Jet For Treatment Of Class Ⅱ Malocclusion

The incidence of Class II malocclusion is very high in clinic. Maxillary molar distalization is the routine method for Class II malocclusion with the maxillary molar mesial movement, without severe maxillary dental arch crowding. The effect of the traditional patient-dependent appliance is rely on the patient cooperation ,and the patient-independent appliance should be modified for some side effects. The domestic Distal jet is' one kind of the modified Pendulum appliance. The oversea clinic researches of this kind of appliance have been reported a lot but no such study is reported in China. In this study, 22 patients with Class II malocclusion were treated with Distal jet by maxillary molars distalization without extraction. Then the effects were evaluated by the 3D changes of the distaled teeth and skeletal through pre- and postdistalization cephalometric radiographs and the dental models analysis,and compares to these effects with similar appliance. This will apply to academic support for the homemade Distal jet to practice. Result1.It needs 5.0 months for Distal jet to change the maxillary molar from Class II malocclusion to Class I molarrelationship.2. The 9-12 years old is the best period for the Distal jet treatment. During this period, the Class II malocclusion treatment will benefit from the upper and lower jaws fast grow3. The distalizing force on the maxillary molar made maxillary molar distalizad and the anchorage lossed. From the first premolar to the first molar, the space of molar distalization is 72.4% and the space of anchorage is 27.6% of the total space. This result is similar to the result of such kind of oversea appliance.4. The first maxillary molars were distalized an average of 3.4mm and were tipped distally an average of 3.3? Compare with Pendulum appliance, the distalizing distance was the shorter. But the molar tipped distally was the smaller and this could provide more space than others.5. Anchorage loss measured at the first premolar averaged 1.3 mm,but the crowns tipped 3.5?distally.During distalization with Distal jet,the first premolar did not tend to tip mesially as found in many investigation of other intraoral distalizing appliance.6. The maxillary incisors were moved labial 1.8 mm andproclined 12.2, the overjet increased 1.7mm. The increasing of procline was partly related to the leveling with maxillary fixed appliance and part since anchorage lossing.7. No significant vertical change was found during the molar distalization.There was no significant inceases in lower facial height,the mandibular .The occlusal and the palatal plane remained virtually unchanged.8. The first maxillary molar was rotatde 2.5-2.7?mesial-lingua direction. And modified Distal jet could effectively limited this unwanted effect.9. After the molars distalization, the maxillary arch was expansion. This is probably advantageous in Class II treatment patients, which have the narrow maxillary dental arch.ConclusionFor no extracted treatment of Class II malocclusion, the homemade Distal jet is an effected intraoral patient-independence appliance for the maxillary molar distalization. This appliance can make less molar tipping distally and less anchorage losing during molar distalization . It will not make maxillary molar significant erupted and can expand the maxillary arch. Compare with thesimilar oversea Distal jet, the domestic Distal jet is suitable for the clinical apply.