A study of hard tissue changes in adults with bimaxillary protrusion treated with customized lingual appliance system plus micro-implant and lever-arm

Abstract

Objective The purpose of this study is to investigate hard tissue changes in adults with bimaxillary protrusion treated with customized lingual appliance system plus micro-implant and lever-arm. Methods The sample comprised 8 adults with bimaxillary protrusion who fulfil the inclusion criteria. An e-Brace customized lingual appliance was applied after extraction of four first premolars. Micro-implant was placed on the palatal side of alveolar bone between the second premolar and first molar on maxilla, 6mm above alveolar bone crest. Lever-arm with 7mm in length was placed in the distal of lateral incisors. Elastic chain was tied between micro-implant and lever-arm for later retraction of the anterior teeth. Pre- and post-treatment cephalometric radiographs were measured by hand. Hard tissue changes were analyzed with one-sample T test (SPSS 22.0). Results After treatment, molar and canine relationships of 8 patients were Class I and normal overjet and overbite were established. These changes of SN-OP(°)、U1-SN(°)、U1-PP(°)、U1-NA(mm)、L1-NB(mm)、L1-MP(mm)、OB(mm)and U1-L1(°)were statistically significant. Conclusions Customized lingual appliances system combined with micro-implants and lever-arm could retract anterior teeth and modify hard tissue protrusion with good outcomes, which could be used as one of the efficient methods to correct bimaxillary protrusion in adults. Key words: Adult orthodontics; Customized lingual appliances system; Micro-implant; Lever-arm; Bimaxillary Protrusion