关键词: 混合牙列期, 个别前牙反牙合, 萌出诱导矫治器, 三维测量分析

Abstract: Objective： To investigate the clinical effect of eruption guidance appliance in the treatment of anterior cross bite in mixed-dentition children. Methods: In the study,10 mixed-dentition children with anterior cross bite，totally 12 incisors, were selected. Alginate was used to take upper and lower dentition impression and make a hard plaster model，which served as the eruption guidance appliance for treatment. The pre- and post-operative dental casts were digitized with SmartOptics Activity 880 scanner，and the three-dimensional overlapping models were obtained by reverse engineering software，Geomagic Studio 2012，then the threedimensional movements of the upper and lower incisors were analyzed using Imageware 13.2 software. The overbite and overjet were analyzed using the same methods. Measurement with copper wire was used to analyze the upper and lower arch length. Space analysis was the result by the sum of crown width minus the arch length. The crown width of unerupted permanent teeth was accor-ding to X-ray method to predict. The SPSS 17.0 software was used to analyze the pre-and post-operative measurements of the same child. The normality test of the measured data showed that it conformed to the normal distribution. Therefore，the t test and double side test were used，and the significance level was 0.05. Results: The course of treatment was (5.6±2.7) months. During orthodontic treatment, the upper incisors moved mainly labially（P<0.001）in three-dimensional displacement，and the lower incisors moved mainly the same direction（P=0.025）. During the treatment of eruption guidance appliance，the average overbite decreased (1.01±0.9) mm（t=-3.531，P=0.006），and the difference was statistically significant. There  was no statistically significant difference between the pre- and post-operative average overjet（t=0.771，P=0.460）. The severity of crowding in upper arch decreased (1.9±0.99) mm （t=-6.042，P<0.001），and that in lower arch decreased (1.9±0.74) mm （t=-8.143,P<0.001）， both of the differences were statistically significant. Conclusion: The anterior cross bite in mixed dentition could be corrected by eruption guidance appliance，and at the same time，the normal overjet and overbite were established，and the teeth were aligned.

Key words: Mixed dentition, Anterior crossbite, Eruption guidance appliance, Three-dimensional analysis