Clinical effects of Angle's Ⅱ1 cases in Alignment with Incognito System

Objective The aim is to reveal the dentofacial changes of Angle Ⅱ1 cases during alignment phase using Incognito lingual orthodontic appliance. Methods Nineteen patients (8 Male and 11 female, aging from 12y to 23y) with Angle Ⅱ1 malocclusion were selected for lingual orthodontic treatment with four premolars extraction. Customized lingual orthodontic appliance (IncognitoTM) was used. Cephalometric radiographs and alginate impressions were taken before treatment and at the end of alignment. The comparison between pre-treatment and post-alignment were analyzed by Paired-Sample Wilcoxon Signed Rank Test through SPSS Statistical Package.Results From the Cephalometric analysis, the following changes were found significantly different (P＜0.05). U1/SN decreased 7.70°. U1/NA decreased 7.94°with 2.85 mr. L1/NB decreased 4.60°with 1.8mm. MP/SN increased 1.52°. L6-MP increased 0.51 mm. L1-MP decreased 1.29mm. OB decreased 1.18mm. From the model analysis, the following changes with significant differences were demonstrated. Upper and lower intercanine widths and lower intermolar widths increased 2.39mm,2.60mm and 1.26mm respectively. Upper arch depth from molar to incisor decreased 2.42mm. The curve of spee became shallow by 1.11mm. Conclusion During alignment phase, the upper and lower incisors tipped lingually with profile improved. The overbite decreased with lower incisors intruded, and the lower molars extruded with mandibular plane angle increased. It implied that lingual appliance would be helpful for lower angle cases with deep overbite, and cautions should be taken from the initial phase during lingual orthodontic treatment in high angle cases.