Читать книгу Management of Complications in Oral and Maxillofacial Surgery - Группа авторов - Страница 69

 Etiology: patient anatomy, excessive force

 Management: removal of displaced teeth in an immediate or delayed fashion, monitoring

The iatrogenic displacement of maxillary and mandibular third molars into adjacent spaces is a rare complication with an unknown incidence [25]. Maxillary third molars can be displaced into the maxillary sinus, buccal vestibule, or posteriorly through periosteum and into the infratemporal fossa [3, 4] (Figure 2.5a and b). Contributing factors for the displacement of maxillary third molars include deep impactions, distoangular impactions, poor visualization and access, inadequate bone removal, lack of a distal stop, and careless elevation [25]. Displacement of mandibular third molars into the submandibular, sublingual, pterygomandibular, and even lateral pharyngeal spaces has been reported along with displacement of roots into the inferior alveolar canal (IAC) [3, 4] (Figure 2.6a–c). The lingual cortex becomes progressively thinner from anterior to posterior in the mandible, and this often results in an extremely thin or even a dehiscence of the lingual plate. Any apically directed forces can easily displace root segments, or an entire tooth, into the aforementioned spaces [3].

Fig. 2.5. (a) Tooth #1 displaced into the maxillary sinus during extraction – panoramic image. (b) Tooth #1 displaced into the maxillary sinus – 3D reconstruction.

Fig. 2.6. (a) CT axial view at the level of the third molars demonstrating tooth #32 displaced into the submandibular space. (b, c) Coronal view CBCT demonstrating mandibular third molar root tips in close approximation to the submandibular space and high risk for displacement.

The management of a displaced third molar tooth or root varies depending upon the space involved. Maxillary third molars displaced into the maxillary sinus should be removed. Root tips <3 mm can be left to fibrose into the sinus mucosa if no previous infection of the tooth or sinus is present and initial attempts at retrieval are unsuccessful [3]. The morbidity of additional surgical procedures outweighs the benefits of removal in this case. An attempt to remove the tooth through the socket can be made by placing the suction tip near the opening into the sinus. Additionally, the sinus can be irrigated through the OAC and suction placed at the opening in an attempt to flush the tooth or root segment out. If the segment is visualized, the opening can be enlarged to allow retrieval. If this is unsuccessful, the surgeon should abandon further attempts at removal through the socket and remove the tooth segment via a Caldwell–Luc approach into the maxillary sinus. This can be completed at the time of initial surgery or in a delayed secondary procedure. If delayed retrieval is planned, the patient should be placed on antibiotics and decongestants, and the OAC closed as described previously [3, 4].

The retrieval of a maxillary third molar displaced into the infratemporal fossa can be complicated by bleeding from the pterygoid plexus, poor visualization, and inability to locate and stabilize the tooth [25]. In general, the tooth is located lateral to the lateral pterygoid plate and inferior to the lateral pterygoid muscle. Lateral and posteroanterior cephalometric films can assist in localizing the tooth, but computed tomography (CT) is preferred if available (Figure 2.7a–f). The surgeon should extend the original incision distally to the tonsillar fauces and, with blunt dissection, attempt to locate the tooth. If this attempt is unsuccessful, the tooth should be left in place and the patient placed on antibiotics. Blind, or limited visualization, attempts to grab or probe for the tooth should be avoided since injury to adjacent structures or further displacement of the tooth can occur. If asymptomatic, the tooth can be left in place and the patient followed closely. Pain, infection, limitation of opening (from tooth impingement on the coronoid process), and patient desire are all indications for removal. This is completed in four to six weeks to allow for fibrosis to occur, the tooth to stabilize, and appropriate imaging (CT, cone‐beam CT [CBCT]) to be obtained. Multiple approaches have been described in the literature, including CT‐guided surgery, needle‐guided fluoroscopic retrieval, transoral retrieval, and hemicoronal flaps [3, 4, 25].

Fig. 2.7. (a) Coronal view CT demonstrating tooth #16 displacement into the infratemporal fossa. (b) Axial view CT demonstrating tooth #16 displacement into the infratemporal fossa and located between the coronoid process and zygoma, limiting maximum incisal opening. (c) Positioning for planned intraoperative navigation. (d) Utilizing a small incision, the navigation system is utilized to locate the displaced tooth. (e) Intraoperative navigation to triangulate the position for removal with minimal dissection. (f) Removed tooth #16 specimen.

Displaced mandibular third molars are most often located in the submandibular space, inferior to the mylohyoid muscle. Attempts at removal should begin with digital pressure against the lingual surface of the mandible to force the root segment back into the mouth/extraction site. The opening into the floor of the mouth can be enlarged slightly to assist in retrieval; however, this should be completed cautiously to avoid injury to the nearby LN. A lingual full thickness flap can be carefully reflected and the mylohyoid muscle incised to gain access to the submandibular space. Due to limited space, hemorrhage, and poor visibility, it may be very difficult to remove the tooth or root segment via this method. Allowing for fibrosis to occur and returning at a later date to remove the tooth or root is acceptable. Often, this is completed via an extraoral approach in the operating room and after CT scanning completed. Yeh has described an intraoral/extraoral approach where a 4‐mm skin incision allowed for insertion of a hemostat and/or Kelly forceps and stabilization of the tooth, while via an intraoral lingual full thickness flap, the tooth was located and removed [26].

Displacement of a root into the IAC should be approached with caution. Attempts at retrieval can further damage the IAN or further displace the root. If the root segment was not infected and the patient does not complain of neurological findings, leaving the root segment may be acceptable. If the root is infected, or the patient has complaints of neurological involvement, it must be removed with caution and consideration made for referral to a microneurosurgeon to evaluate whether nerve repair may be necessary [4].