Clinical Study Related To The Extraction Of The Unhealthy First Molars On Orthodontic Treatment

ObjectiveThe purpose of this study was to evaluate the clinical effectiveness of orthodontic treatment with first molar extraction.MethodsA retrospective study of 37 cases were selected, mean age 19.8±5.8years old, treated with the extraction of unhealthy first molars. All patients were treated with straightwire appliance. The treatment effects were evaluated by pre-and post-study casts, profile photos and panoramic and cephalometric films.ResultsAll cases achieved satisfactory closure of first molar space, good occlusal relationship and soft tissue profile with average treatment duration of 27.1±4.8 months. The percentage of weak anchorage design was 48.6%, medium anchorage design was 37.8%, which meant space closure of first molar mainly depended on forward movement of second molar. The causes for 27 of the 64 extracted first moalrs was due to lost,28 for residual crown or foot and 8 for grandly filling. The roots of second premolar and second molar after treatment were parallel. There were no evidence that the second molar had remarkable root resorption and alveolar bone resorption.ConclusionExtraction of unhealthy first molars would obtain satisfactory results by careful anchorage design and proper clinical operation.