Correction Of Anterior Open Bite Malocclusion Utilizing V-bend Arch Wires:A 3-dimensional Finite Element Analysis

Anterior open bite is one of the common malocclusions in clinic.Unlike other malocclusions,anterior open bite not only seriously affects the mastication and pronunciation function of patients,but also affects their facial appearance,which has a negative impact on the social life and psychology of patients and greatly reduces the quality of life of patients.Meanwhile,correction of anterior open bite has been a gareat challenge for orthodontists not only because of its numerous etiologic factors and complex pathogenesis,but also treatment is quite differential in different development periods and for different etiology and pathogenesis.Stability and retention after treatment has been a tough problem as well.Orthodontic compensation can achieve satisfactory results for dental anterior open bite or minimal skeletal anterior open bite.In fixed orthodontic treatment,tip-forward bending of arch wires can extrude the anterior teeth which is used for compensation.However,a divergency of palate plane,functional occlusal plane and the mandibular plane is often seen in the anterior open bite patients,which leads to the mesial inclination of the maxillary molars axis and the mandibular molars axis.More mesial-tipping of the molars and lifting of the fulcrum may occur due to the mesial tipping moment to anchorage molars produced by tip-forward bends,resulting in worsen anterior open bite.Tip-back bending of arch wires will upright mesial-inclined molars but intrusion force is produced in the anterior segment in return,which is unfavorable for correction of anterior open bite.In this study,V-bend mechanical behavior was discussed,and the initial displacement of the teeth under typical V-bend arch wires was analyzed.The purpose was to provide guidance and advice for the clinical application of V-bend when correcting the anterior open bite.By constructing a 3-dimensional finite element model of "2×4" appliance system including maxillary dentition and brackets that clinical reality was simulated,force and moment of teeth under different V-bend arch wires was calculated with FEA software in three dimensions.Results was found as followings.No neutral points existed in this force system.No vertical force existed at location 0.41 for the first molar and incisors.Moment reversed at 0.38 location for the first molar and 0.59 for lateral incisor.Central incisor underwent no force nor moment reverse the whole time.Initial displacement of teeth under molar tip-forward arch wire implied unfavorable effects when correcting anterior open bite.