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480 RETRIEVAL OF DISPLACED THIRD MOLAR

Oral Maxillofac Surg8:480-485, 2010

Retrieval of a Displaced Third MolarUsing Navigation and Active

Image Guidance

Andrew Campbell, DDS,* and Bernard J. Costello, DMD, MD†

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isplacement of a third molar tooth during routineurgical extraction is a rare event and well-docu-ented in the literature.1-6 Even the most experi-

nced surgeons may have this occur on occasion.axillary third molar teeth can be displaced into a

ariety of locations including the buccal space, infra-emporal fossa, maxillary sinus, or other tissue planes.

e report a technique of easy retrieval using an activeavigation image guidance system. This specific indi-ation has not been well reported, and it is importantor dentoalveolar surgeons to be aware of the capa-ilities of the latest technology.

eport of a Case

An 18-year-old healthy female patient had a consultationith another surgeon for removal of pathologically im-acted third molars, and surgical removal of the teeth wasecommended (Fig 1). The complete bony impactions werepproached in typical fashion using a small incision alonghe lateral aspect of the alveolar crest in the area of thempacted tooth. A subperiosteal dissection was appropri-tely completed, but during elevation the right maxillaryhird molar was displaced beneath the flap. An immediatexploration was performed to locate the tooth but wasubsequently terminated without success. Postoperatively,he patient displayed diplopia on upward gaze, warrantingvaluation by an ophthalmologist. Visual acuity and all otherspects of her examination were normal with the notablexception of diplopia on extreme upward gaze. A CT scanas obtained to localize the now “foreign-body,” and theatient was referred to the senior author for treatment (Fig). A minor orbital disruption was noted on the scan, withisruption of the tissues surrounding the inferior rectus.

eceived from the Department of Oral and Maxillofacial Surgery,

niversity of Pittsburgh School of Dental Medicine, Pittsburgh, PA.

*Pediatric Oral and Maxillofacial/Craniofacial Fellow.

†Associate Professor and Program Director, Chief, Craniofacial

nd Cleft Surgery.

Address correspondence and reprint requests to Dr Costello:

epartment of Oral and Maxillofacial Surgery, 3471 Fifth Avenue,

uite 1112, Pittsburgh, PA 15213; e-mail: bjc1@pitt.edu

2010 American Association of Oral and Maxillofacial Surgeons

278-2391/10/6802-0040$36.00/0

aoi:10.1016/j.joms.2009.06.032

After 6 weeks of healing the patient was scheduled forurgical removal of the displaced tooth and, now, foreignody. At 6 weeks, the diplopia had almost completely re-olved and was only present during extreme upward gaze.

computed tomography scan was obtained as per therotocol for use with the Stryker System II Navigation imageuidance apparatus (Stryker, Kalamazoo, MI). The patientas brought to the operating theater and placed under

eneral anesthesia with a nasal endotracheal tube. Thetryker System II uses a light emitting diode (LED) mask toegister the CT data with the patient in the operating the-ter and correlates the data with the hand-held probe/uction device (Fig 3). An accuracy of 0.5 mm was antici-ated after calibrating the system. Multiple views allowed

ocalization of the tooth within minutes (Fig 4). A smallestibular incision was made beneath the zygomatic but-ress, and a suction/probe was used to determine the exactocation of the medial and lateral aspects of the occlusal sur-ace of the tooth. After precise localization the tooth wasluntly dissected free and removed (Fig 5). Blood loss wasinimal, and the incision was closed with a running 3-0 chro-ic suture. The entire procedure was completed withininutes, and the patient was discharged several hours later.

iscussion

Complications from third molar removal are, thank-ully, rare. The most common complications occurith regular frequency. These include infection (0.8%

o 4.2%),7-13 alveolar osteitis (0.3% to 26%),7-15 infe-ior alveolar nerve injury (0.4% to 8.4%),8,18,19 lingualerve injury (0% to 23%,10,18,20 with approximately.5% being permanent21-23), and clinically significantemorrhage (0.1% to 0.7%).7,10,24 Rare complicationsf third molar removal include mandible fracture0.0033% to 0.0049%),16,17 osteomyelitis, and displace-ent of teeth during removal, for which the incidences

re unknown. It is likely that displacement of teethuring removal of third molars is under-reported, asost surgeons retrieve their own displacements with-

ut reporting the complications.The typical management of displaced third molar

eeth involves an initial, conservative attempt to re-ove the tooth from the area in which it is believed

o be displaced. If initial retrieval fails then the regions irrigated and closed, and the patient is placed on

ntibiotics. Imaging is obtained to localize the tooth

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CAMPBELL AND COSTELLO 481

n 3 dimensions. Imaging is recommended soon afterhe event to determine whether displacement of theooth may affect function of another anatomic areaeg, the orbit). If the tooth is displaced into a criticalnatomic area such as the orbit, early removal may bendicated. In most other instances, the tooth is left inosition until initial scarring occurs over severaleeks. The authors prefer to wait approximately 6eeks.

FIGURE 1. Panoramic tomogram of the patient w

ampbell and Costello. Retrieval of Displaced Third Molar. J Ora

IGURE 2. Computed tomography images of the maxillary righthird molar displaced lateral to the orbit, and medial to the zygo-atic arch.

ampbell and Costello. Retrieval of Displaced Third Molar. J Oralaxillofac Surg 2010.

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Iatrogenically, displaced teeth are traditionally ap-roached after careful planning using detailed imag-

ng in multiple planes followed by the use of extendedntraoral incisions. Difficulties may be encountered wheneeth are displaced into areas where the tooth can con-inue to migrate; this is particularly the case withnderdeveloped teeth without roots. Difficult-to-ac-ess areas include the buccal fat pad, infratemporalossa, sinus cavity, floor of mouth, masticator space,r other areas of loose fascial planes. A waiting periodf at least several weeks allows fibrous encapsulation

thologically impacted teeth before displacement.

llofac Surg 2010.

IGURE 3. Stryker LED mask positioned on patient to allow regis-ration and active navigation.

ith pa

ampbell and Costello. Retrieval of Displaced Third Molar. J Oralaxillofac Surg 2010.

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482 RETRIEVAL OF DISPLACED THIRD MOLAR

f the displaced tooth to occur. This tends to resisturther displacement into other anatomical planes.orrelation of the position of the tooth with a multi-lane CT scan makes this approach reasonable for mostinimally displaced teeth. However, surgical dissection

nd manipulation of the tissues can change referenceoints for the operating surgeon, and further displace-ent of the tooth can occur. Although some retrievalsay be easy, others can be difficult, with risk ofemorrhage or neurologic injury, and may even re-uire aborting the procedure if the tooth is not lo-ated. Failure to locate the displaced tooth then re-uires the surgeon to use additional approaches orechnologies for retrieval. Orr25 reported on the in-ratemporal displacement of a right maxillary thirdolar. In his technique an 18-gauge spinal needle was

nserted above the zygoma and posterior to the orbitalim. The needle was used to exert pressure on theooth from a superior direction while manipulatingntraorally to retrieve the tooth. Additional methodseported for removing teeth from the infratemporalossa include the combination of intraoral incisionsith a standard Gilles approach,26 a transantral ap-roach,27 and use of intraoperative fluoroscopy.28

Another technique reported for locating and re-

IGURE 4. Multiplanar views of the displaced third molar using teal time. Probe positioned at inferior–anterior aspect of displaced

ampbell and Costello. Retrieval of Displaced Third Molar. J Ora

oving a displaced third molar not retrieved with a a

imple intraoral incision involves a coronal or hemi-oronal approach, dissection of the temporalis mus-le off the lateral skull, and entrance into the infra-emporal fossa.29 Although this is a viable approach, its aggressive in comparison with the incisions andecovery expected after routine third molar toothemoval. This technique works very well and pro-ides maximal surgical exposure; however, the ag-ressive nature of the procedure has a number ofossible complications associated with it, includingrismus, a residual coronal scar with hair loss, facialerve palsy, temporalis wasting, temporal hollowing,nd significant blood loss. These factors limit thispproach to teeth that cannot be accessed in anyther manner. In rare instances a brow incision maye used to work in concert with an intraoral incisiono manipulate the foreign body from 2 locations in ainimally invasive fashion. Although this procedureas not necessary in the current case, it could beerformed with a higher degree of accuracy withctive navigation if necessary.

Image-guided navigation applications for surgeryere first developed for use in neurosurgery.30-33 Nav-

gation techniques with image guidance for crani-maxillo-facial procedures have been popularized by

ion probe to identify the precise location of the displaced tooth inmolar.

llofac Surg 2010.

he suctthird

number of individuals.30-32,34-37 As the technology

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CAMPBELL AND COSTELLO 483

as been refined, its initially cumbersome nature haseen supplanted with standard protocols that haveecome routine in most major medical centers.Head frames were originally used for stereotactic

rain surgery and localization of lesions for other onco-ogic therapies. For many craniomaxillo-facial proce-ures these may be inconvenient or cumbersome tose. External fiducials placed before CT scanning orhe use of an external mask with multiple LEDs areore commonly employed for procedures in crani-

maxillo-facial surgery. The latter are more recentevelopments and do not require rigid immobilization

n a stereotactic head frame. In image-guided surgerysing an optical tracking system the LED mask islaced on the patient, and a camera system connectedo the CPU localizes the position of these infrared-EDs and then merges the radiographic images withhe actual position of the patient.30 The registrationrocedure using the mask is quick and highly accu-ate. Navigation systems are classified as either activer passive. Active navigation systems place infraredEDs on the patient and a camera records their posi-ion; passive systems have no LEDs but rather usepheres to reflect infrared light emitted by the cameraystem.30 Active systems avoid problems created bybstructing or soiling of the reflecting spheres andverlap of reflections that can occur with passiveystems.38 Various probes containing position sensorsay be used, including several varieties of suction

atheters. Tracking systems follow the position of the

IGURE 5. Removal of the third molar took just minutes using thisechnique.

ampbell and Costello. Retrieval of Displaced Third Molar. J Oralaxillofac Surg 2010.

urgical instruments and the patient, the system then t

isplays the 3-dimensional relationship of the probeo the patients’ anatomy. Accuracy with the probes isypically better than within 1 mm.30

This technology has become useful as the conver-ence of a variety of technologies including highlyccurate imaging, user-friendly software applicationsor navigation, and systems to correlate these data ineal time with a high degree of precision. Improve-ents in navigation technology and availability have

ed to a drastic increase in its application over the lastecade. Image-guided navigation in the craniomaxil-

ofacial region has been used in oncologic biopsiesnd resections,32,35 craniofacial reconstruction,36,39

acial trauma,40 dental implantology,37 arthroscopy ofhe temporo-manibular joint,37,41,42 facial osteoto-ies,37 and removal of foreign bodies.30,31,34

Limitations when using image-guided navigation ex-st and are important to consider. Intraoperative ac-ivity is based on the preoperatively acquired imageata. Changes occurring at the surgical site duringanipulation are not represented on images viewed

y the surgeon.31,32 Performing surgical proceduresn highly mobile tissues, such as the tongue, may benreliable and limited.31 When retrieving foreign bod-

es any further iatrogenic displacement will make thereoperative images less useful.Registration accuracy is crucial for the accuracy of

avigation.43,44 The accuracy obtained depends onhe tracking system used; on the design, number andrrangement of fidicial markers; and on the imageata. In reality, marker position on the patient alwaysiffers slightly from positions displayed on the image,ut this difference is routinely reduced to less than 1m.30,31 A disadvantage to optical navigation systems

elates to the line of sight. A camera senses the LEDarkers on the patient for registration; to track instru-ents relative to the patient the camera must con-

inue to have the markers in view. The surgeon mustosition both himself or herself and the patient ap-ropriately at all times to avoid obstruction of the linef sight. This is not difficult for most procedures butust be considered during set-up of the equipment.Many image registration systems require that mark-

rs be placed on the patient before image acquisitionr that images be acquired in a specific protocol that

s not routine during initial diagnostic radiography. Toetermine the need for image guided navigation theatient will have already received diagnostic imaging.he patient would then need additional imaging forppropriate registration. There is additional cost andadiation exposure when CT scanning is used.30

Removal of foreign bodies using navigation haseen discussed in previous publications.30,31,34 How-ver, this specific indication has not been well re-orted, and it is important for dentoalveolar surgeons

o be aware of the capabilities of current systems.

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484 RETRIEVAL OF DISPLACED THIRD MOLAR

his technique allowed exceptionally quick removalf the foreign body with precise localization. Thisermitted us to avoid exploratory blunt dissection inhe infratemporal fossa and to limit postoperativeain, swelling, and potential scarring for our patient.his minimally invasive approach resulted in a de-reased likelihood of complications, as well as inmproved recovery and a better experience for theatient and family when compared with more ag-ressive techniques previously described. The usef navigation provided a safe and precise approacho the region without the need for extensive explo-ation while avoiding significant vasculature andther structures of concern to remove the displacedooth. Given the disruption of the orbit and inferiorectus from the previous procedure, we consideredhis very important.

Iatrogenic displacement of a third molar duringoutine surgical extraction occurs rarely and is likelynder reported. It can occur even to the most expe-ienced of surgeons. Using navigation allowed us toemove a displaced wisdom tooth in a minimally in-asive fashion in minutes. This technique allows ex-eptionally accurate localization and removal of dis-laced teeth, which provides a much better solutionhan the more aggressive approaches described in theiterature. It also affords a margin of safety with dis-ection in this region that has heretofore not beenossible with traditional techniques. In cases inhich surgical manipulation may affect the globe,

asculature, or various nerves in the region, the accu-acy of navigation provides a predictable road map foruccessful removal of significantly displaced third mo-ars.

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