Retrieval of a Displaced Third Molar Using Navigation and Active Image Guidance

An 18-year-old healthy female patient had a consultation with another surgeon for removal of pathologically impacted third molars, and surgical removal of the teeth was recommended (Fig 1). The complete bony impactions were approached in typical fashion using a small incision along the lateral aspect of the alveolar crest in the area of the impacted tooth. A subperiosteal dissection was appropriately completed, but during elevation the right maxillary third molar was displaced beneath the flap. An immediate exploration was performed to locate the tooth but was subsequently terminated without success. Postoperatively, the patient displayed diplopia on upward gaze, warranting evaluation by an ophthalmologist. Visual acuity and all other aspects of her examination were normal with the notable exception of diplopia on extreme upward gaze. A CT scan was obtained to localize the now “foreign-body,” and the patient was referred to the senior author for treatment (Fig 2). A minor orbital disruption was noted on the scan, with disruption of the tissues surrounding the inferior rectus. After 6 weeks of healing the patient was scheduled for surgical removal of the displaced tooth and, now, foreign body. At 6 weeks, the diplopia had almost completely resolved and was only present during extreme upward gaze. A computed tomography scan was obtained as per the protocol for use with the Stryker System II Navigation image guidance apparatus (Stryker, Kalamazoo, MI). The patient was brought to the operating theater and placed under general anesthesia with a nasal endotracheal tube. The Stryker System II uses a light emitting diode (LED) mask to register the CT data with the patient in the operating theater and correlates the data with the hand-held probe/ suction device (Fig 3). An accuracy of 0.5 mm was anticipated after calibrating the system. Multiple views allowed localization of the tooth within minutes (Fig 4). A small vestibular incision was made beneath the zygomatic buttress, and a suction/probe was used to determine the exact location of the medial and lateral aspects of the occlusal surface of the tooth. After precise localization the tooth was bluntly dissected free and removed (Fig 5). Blood loss was minimal, and the incision was closed with a running 3-0 chromic suture. The entire procedure was completed within minutes, and the patient was discharged several hours later. Discussion Complications from third molar removal are, thankfully, rare. The most common complications occur with regular frequency. These include infection (0.8% to 4.2%), 7-13 alveolar osteitis (0.3% to 26%), 7-15 inferior alveolar nerve injury (0.4% to 8.4%), 8,18,19 lingual nerve injury (0% to 23%, 10,18,20 with approximately 0.5% being permanent 21-23 ), and clinically significant hemorrhage (0.1% to 0.7%). 7,10,24 Rare complications of third molar removal include mandible fracture (0.0033% to 0.0049%), 16,17 osteomyelitis, and displacement of teeth during removal, for which the incidences are unknown. It is likely that displacement of teeth during removal of third molars is under-reported, as most surgeons retrieve their own displacements without reporting the complications.