Effect of sagittal overcorrection design on displacement and stress of mandibular anterior teeth intrusion using clear aligners / 中国组织工程研究

ABSTRACT

BACKGROUND:The thin alveolar bone in the lower anterior region increases the risk of labial bone resorption when intruding the teeth with clear aligners.The effect of sagittal overcorrection design on the labiolingual control of mandibular anterior teeth intrusion has not been fully investigated. OBJECTIVE:To explore the effect of overcorrection on the changes in the displacement and stress of the mandibular anterior teeth,especially the cervical and apical regions. METHODS:Through a male volunteer cone-beam CT data,the three-dimensional reconstruction of the mandible and teeth was conducted in the MIMICS and GEOMAGIC software.Moreover,the models of periodontal ligaments,attachments,and appliances were created in the SOLIDWORKS software.First,the study was divided into canine intrusion group and incisor intrusion group.Then,the overcorrection(0°,1°,2°)was designed on the bilateral mandibular central and lateral incisors.A total of six models were established.The models were assembled and imported into the ANSYS software to analyze and calculate the displacement and stress level. RESULTS AND CONCLUSION:(1)In the canine intrusion group,canines intruded and tipped lingually while incisors extruded and tipped lingually.In the incisor intrusion group,canines extruded and tipped lingually while incisors intruded and tipped lingually.(2)Without overcorrection,the incisors necks moved lingually while apexes moved labially.With overcorrection,the incisors tended to be upright,followed by labial tilt.The least cervical and apical displacements were detected under 1° overcorrection.(3)With overcorrection,the incisal cervical stress concentration area shifted from labial to lingual in the canine intrusion group,whereas the stress concentration area shifted from lingual to labial in the incisor intrusion group.(4)The incisors tended to tilt lingually when intruding the mandibular anterior teeth with clear aligners.The sagittal overcorrection design was conductive to maintain the stable position of incisors.However,the amount of overcorrection should be moderate.Excessive overcorrection might increase the labial inclination tendencies of incisors.