To Örebro University

Deep bite is a condition in which the maxillary and mandibular arch of teeth overlap with each other. Mandibular central incisor and mandibular canine are extruded significantly in this case. Hence, they need to intrude apically. The segmented arch technique is more effective than any other method for the correction of deep bite. However, there is no significant research to use a segmented arch technique in lingual orthodontics. Hence, the aim of the present research study is to specify accurate tilt (toe) angles in lingual orthodontics (LiO) required for intrusion of the mandibular central incisor and mandibular canine tooth for different positions from respective occlusal plane and to state comparative assessment of required tilt angles for both the teeth. For this purpose, single intrusive force was considered to act from top surface of a lingual bracket of the mandibular tooth. The position of application of intrusive force was considered from two factors, i.e. horizontal distance of bracket top surface from tooth surface and vertical distance of bracket top surface from an occlusal plane. In the present study, four different values of vertical distance of bracket top surface from an occlusal plane were considered. Thus, four different positions of application of intrusive force were considered for both the teeth (mandibular central incisor and mandibular canine). Required (optimum) tilt angles were computed mathematically for each tooth to pass the intrusive force vector through Cres. It is then verified with finite element analysis of CAD models of tooth assemblies. For the mandibular central incisor, the tilt angle was found to be 0 degrees for vertical distance of 3 mm from an occlusal plane (OP). While, for mandibular canine, the tilt angle was found to be 0 degrees for vertical distance of 2 mm from an occlusal plane (OP). Hence, these positions of point of application of intrusive force can be considered as better positions than others clinically.