Correction of bilateral heavily impacted second molar with improved super-elastic nickel-titanium alloy wires

Abstract

Impaction and an abnormal eruption of a secondmolar occur because of a lack of retromolar space, premature eruption of the mandibular third molar, and ankyloses. The prognosis must be carefully considered when extracting a damaged permanent tooth. In addition to extraction for orthodontics, this enables the establishment of an effective force system to align the impacted tooth. A 21-year-old woman exhibited maxillary anterior crowding, deviation of the maxillary midline, and deeply impacted mandibular secondmolars bilaterally. The molar relationship was Class II. The cephalometric analysis demonstrated a skeletal Class I relationship (ANB angle, 1.4°); maxillary and mandibular incisors were lingually inclined. Cone-beam computed tomography images indicated that root resorption, caries, and periodontitis were absent in all mandibular molar. Mandibular second premolars were extracted to relieve crowding and achieve Class I molar relationships. The second molars moved mesially on both sides, and there were no signs of ankylosis. We used improved super-elastic nickel-titanium alloy wire (ISW) to upright the mesioangular secondmolars. We heat-treated the anterior portion of the ISW, including the first molar area, to increase wire stiffness; the posterior portion of the ISW, including the impacted secondmolar area, remained untreated to ensure that its super-elasticity was preserved. We alleviated crowding, corrected the maxillary midline, and created ideal occlusion with Class I relationship. This case shows that the alignment of a deeply impacted tooth with a heat-treated ISW, combined with voluntary adjustment of wire stiffness, can be a simple and useful treatment option for adult patients.