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Main Instructor Yu-Chih Wang
Department / Institution Department of Stomatology , National Cheng Kung University Hospital, Tainan, Taiwan
Classification Case report
Management of deeply impacted maxillary canine is a challenging orthodontic task in terms of anchorage and biomechanical designs. Meanwhile, the skeletal Class III malocclusion with negative overjet further increases the orthodontic complexity and treatment time. The aim of the presentation is to describe the orthodontic treatment of an adolescent female patient with skeletal class III and bilateral maxillary canine impaction.
  A 12.5-year-old female adolescent presented with a chief complained of delay tooth eruption, crooked lower anterior teeth and reverse bite. She was diagnosed with skeletal Class III with a hyperdivergent facial pattern and dental Class III malocclusion with 3 mm of overbite and -2 mm of overjet. Bilateral maxillary canines were buccally impacted, with the crown completely overlapping and displacing the roots of lateral incisors. She was in the late mixed dentition stage with the retained primary molars in the maxilla and the mandible. Through the proper utilization of leeway space and orthodontic arch expansion, the arch discrepancy was resolved and proper overjet and overbite were established. After the space was regained for the impacted canines, a 0.017x 0.025-inch stainless wire along with slightly activated Nickel-Titanium open coil springs were placed as the anchorage plan. Upper canines were surgically exposed and were guided with the closed force-eruption procedure. A nickel-titanium tension coil spring was applied between the attachment on the buccal side of canine crown and the heavy main wire. The distally directing coil spring generated a light continuous force to upright and properly repositioned the impacted canines in the upper arch. The treatment was accomplished in 3 years. Solid Class I occlusion with positive overbite and overjet was achieved. The impacted canines were well aligned with good periodontal health and without evidence of severe root resorption
 「Discussion and summary
   An accurate identification of the location and removable of possible obstacles are prerequisites to the success of force eruption of impacted teeth. A nickel-titanium tension coil spring with the proper biomechanical design in the closed force-eruption procedure is recommended to successfully guide deeply impacted canine eruption. The management of leeway space could provide additional space for correction of arch discrepancy and anterior cross-bite in the late mixed dentition stage.  
Orthodontic Treatment of Maxillary Impacted Canines in A Skeletal Class III Adolescent