The Orthodontic Treatment Of The Congenitally Absent Lower Lateral Incisor

Objective:To investigate dental and craniofacial changes in soft and hard tissue and facial profile changes in the congenitally missing lower lateral incisor,mandibular retrotrusion and maxillary dentition with severe overcrowding, classⅡ1malocclusion patient after orthodontic extraction treatment.To use the analysis of Bolton index on the role of correction alternatives, as well as single-jaw extraction treatment of the advantages.Materials and method:A female case classⅡ1 malocclusion was selected from DaLian Ortho clinic in April 2008,who was 13.2 years old, right buccal segment relationship:cusp-to-cusp class II relationship; life buccal segment relationship:class II relationship, normal maxllary, re-trotrusion mandible,sever crowded of upper arch.The patient was extracted two first premolar maxillary with edgewise appliance. In the course of treatment, use two steps to close the tooth space. Uptake x-ray lateral radiographic films pre-and post-treatment in a week.39 hard and soft tissue marked points of cephlometric radiographs were drawed in a period time.24 typical measurements were selected from Beijing Medical University,Tweed analysis,so as to observe the changes from pre-and post-treatment.Results:The course of orthodontical treatment is 22months.Compared the changes between pre-and post-treatment:Molar relationship didn't changed, facial profile was improved; SNA didn't changed,SNB increased 0.5°,ANB decreased 0.5°;Overjet decreased 2mm;NA/PA decreased 0.5°(decreased from 7°to 6.5), There are obvious changes in mandibular retrotrusion.The vertical relationship wasn't improved,the angle of MP/SN is increased.The mandibular plane was slightl clockwise rotation.The profile of soft tissue improved obvious,which changed from convex surface type tending todirectly facing type.The NLA increased from120°to 125°,The Z angle increased from 75°to 77°, The Li-E increased from-2mm to-1mm.The patient and her parents were satisfied with the result of orthotherapy after treatment.Conclusions:ClassⅡmalocclusion with mandibular retrotrusion and sever crowed of maxillary can be treated successfully by edgewise appliance with extraction two first premolar. The result can be satisfied from the improved:overjet,the profile of soft tissue.