CASE REPORT

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The patient was a 56-year-old man who was allergic to penicillin and had a medical history significant for asthma. He visited the Oral and Maxillofacial Surgery Service, Veterans Affairs Medical Center, Minneapolis, with a chief complaint of extensive dental caries and an interest in receiving dental implants in the mandibular arch.

On clinical examination, the patient exhibited multiple, decayed, nonrestorable teeth in the partially dentate mandibular arch and a completely edentulous maxillary arch. He had minimal periodontal bone loss in the mandibular teeth. Imaging studies included a panoramic radiograph and selected periapical radiographs, which showed adequate bone height for implant placement in the anterior mandible. I determined that the patient was a good candidate for immediate placement of implants after extractions and alveoloplasty. I decided to place five mandibular endosseous implants in the anterior mandible using intravenous, or IV, sedation.

	SURGICAL PROCEDURE

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Auxiliary staff members and I prepared the patient for in-office IV sedation. I gained IV access in the patient’s left antecubital fossa and achieved conscious sedation without incident. Local anesthesia was achieved via bilateral inferior alveolar nerve, lingual nerve and mental nerve blocks with the use of a 25-gauge needle (with negative aspiration). Once the local anesthetic had taken effect, I examined and palpated the mandible, and palpated and marked the mandibular foramen area. Next, I made a crevicular incision with distal releases bilaterally, making sure to stay distal to the exit of the mandibular canal bilaterally.

After making the incisions, I elevated a full-thickness mucoperiosteal flap, exposing the mandible; I then visualized the mental foramina bilaterally. Dissection of the nerve was not necessary at this time. I elevated and extracted the teeth without complication. I then performed an alveoloplasty, using a pear-shaped bur in a Hall (Linvatec, Largo, Fla.) surgical handpiece under copious irrigation. The alveoloplasty resulted in a flat table of bone approximately 7 millimeters in width from canine to canine. With the aid of a caliper, I marked the positions of the implants on the mandible, approximately 8 mm apart. I drilled a pilot hole at the most proximal implant site on the right mandible, working toward the most proximal site on the left mandible. All drilling was done with the aid of a surgical handpiece that had external and internal cooling capabilities.

The most likely cause of sublingual hematoma is bleeding from perforation of the lingual cortex and violation of one of the branches of the sublingual or facial arteries.

Floor-of-mouth elevation. I used a 2.0 pilot drill to enlarge the pilot drill sites, paying attention to parallelism. The osteotomy sites were enlarged sequentially with the use of 3.0-, 4.0- and 4.2-mm burs to a depth of 15.0 mm; parallelism was maintained with the use of parallel guide pins. I did not note any perforation of the lingual cortex during the drilling process. During final preparation of the implant sites, I noted a rapidly progressing elevation of the floor of the mouth on the patient’s right side. It appeared that the patient was developing a sublingual hematoma. I performed digital compression on the floor of the mouth, and notified the anesthesia department immediately.

The patient was awakened, and he remained in hemodynamically stable condition. I did not note any respiratory distress. His electrocardiogram, or ECG, exhibited no changes from baseline measurements, and the patient continued to maintain oxygen saturation above 96 percent on 4 liters of supplemental oxygen delivered via a nasal cannula. Digital pressure was maintained for approximately 20 minutes. I administered 900 milligrams of clindamycin intravenously over 20 minutes.

I decided to aspirate the swelling of the floor of the mouth using a 19-gauge needle. I aspirated multiple sites of the fluctuant mass, with no significant evacuation of fluid. I then performed a lingual subperiosteal dissection to the inferior aspect of the lingual cortex lateral to the genial tubercles bilaterally; I did not note any perforation of the lingual flap. After reflecting the lingual flap, I carefully inspected the lingual cortex, and did not note any perforation or vessels. I used a dental explorer to feel for any perforation on the lingual cortex.

Implant placement. The swelling appeared to have crossed the midline, but elevation of the floor of the mouth was much greater on the left side than on the right side. A definite purpura was developing bilaterally. I observed the patient for 20 more minutes, and did not find any significant expansion of the sublingual hematoma. Using normal saline, I performed copious irrigation of the surgical site. I then removed the implants from their sterile container, placed them on the field in sterile fashion and placed them in the osteotomy sites sequentially from right to left, tapping them into the correct position. All of the implants were secure, and all of the hydroxyapatite coating was covered. After placing the implants, I further inspected the lingual cortex, and did not find any perforation.

I thoroughly irrigated and suctioned the patient’s mouth. Using 4-0 polyglactin 910 sutures (Vicryl, Ethicon, a Johnson & Johnson Co., Somerville, N.J.) with interrupted horizontal mattress suturing, I performed primary closure. After suturing, I again irrigated and suctioned the patient’s mouth. The patient then was admitted to the telemetry unit of the hospital for observation.

The patient remained in stable condition overnight, and did not require supplemental oxygen or intubation. The sublingual mass exhibited partial resolution during his one-night hospital stay. I prescribed a one-week course of oral antibiotics on discharge from the hospital, along with routine postoperative medications. His one-and two-week follow-up examinations showed continuing resolution of the hematoma, and no further postoperative complications. A postoperative lateral cephalometric radiograph was obtained immediately after stage II implant surgery, which was performed by a fellow resident (Figure).

View larger version (72K): [in this window] [in a new window]   Figure. Lateral cephalometric radiograph after implants were uncovered.

	DISCUSSION

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According to the case reports, surgical intervention was required for eight of the patients,^2–4,8–11 and usually involved clamping and ligation of the offending artery. In three of the 10 cases,^3,4,11 the hematoma developed after discharge from the surgeon’s care, which may have delayed life-saving intervention. One case report even involved a dissecting hematoma, which could have led to hemorrhagic shock, airway obstruction, asphyxia or death.^1,2

Causes of sublingual hematoma. Sublingual hematoma formation after implant placement is an uncommon complication, but it is potentially life-threatening. Cases of sublingual hematomas have been reported after other oral surgical procedures, including osteotomies, extractions and biopsies of the floor of the mouth.^3,4 The most likely cause is bleeding from perforation of the lingual cortex and violation of one of the branches of the sublingual or facial arteries.⁹

A study by Nager and colleagues¹² revealed accessory midline foramina above or below the genial tubercles in 72 percent of specimens, which included both dry and cadaveric skulls. This incidence is lower than the 85 percent and 88.9 percent incidences previously reported by Sutton¹³ and Shiller and Wiswell,¹⁴ respectively. These studies included accessory foramina on the entire lingual aspect, not just in the region of the genial tubercles. Practitioners also should consider other sources of potential hemorrhage and subsequent hematoma formation, including injury to muscle or other soft tissues.^9,10

The anatomy of the inferior region of the anterior mandible makes it vulnerable to perforation, especially in cases of atrophy or increased length of dental implants. Relatively small perforations can lead to large hematomas. It seems feasible that an arterial bleed could discharge considerable blood into the lingual soft tissues. Morden-field and colleagues² suggested that the bleeding essentially could tamponade itself as a result of pressures from the adjacent soft tissues. Often, the offending vessel will constrict and retract, which decreases the likelihood of safely locating the vessel via a transoral approach without compromising the patient’s airway.^4,5 Delayed sublingual hematoma formation may be the result of reflex vasodilation or rebound vasodilation after the effect of vasoconstrictors from local anesthetics wears off.^3,6

The exact cause of the sublingual hematoma in the patient described above is unclear. During the drilling procedure, I did not note any tactile perforation, and careful inspection of the lingual cortex did not reveal any obvious perforation after I performed a clean subperiosteal dissection of the lingual cortex. No obvious source of hemorrhage was apparent after I elevated the lingual flap. Because of the rapid formation of the hematoma, it is unlikely that infiltration of local anesthetic into the lingual soft tissues of the floor of the mouth before the procedure was the source of bleeding.

Treatment of an acute sublingual hematoma requires early recognition and intervention.

On re-evaluation, I noted that one of the five endosseous dental implants was in the symphysis region, and this was confirmed by a panoramic radiograph. In retrospect, the mid-line mandible should have been avoided, owing to the close proximity of feeder vessels that enter near the genial tubercle.¹⁵ It is likely that a perforation of the lingual cortex occurred during the surgical procedure, which was not evident clinically even after I carefully evaluated the surgical site.

In cases involving immediate placement of implants or recent tooth extractions, the practitioner should be careful not to use the extraction socket as a guide for angulation because this may lead to perforation of the lingual cortex.⁵ A preoperative lateral cephalometric radiograph may help determine the inclination of the anterior mandible. This imaging study also may be helpful in evaluating implant placement if a perforation is suspected. Soft-tissue management during the procedure is essential, and clinicians should make every attempt to avoid subperiosteal tears that could contribute to sublingual hematoma formation.

Treatment. Treatment of an acute sublingual hematoma requires early recognition and intervention. Initially, the practitioner should assess and secure the airway, as well as administer supplemental oxygen if airway compromise has occurred. Prompt notification of emergency medical services or the anesthesia department (if in-house) is warranted.

The practitioner should monitor the patient’s condition via ECG, pulse oximetry and measurement of end-tidal carbon dioxide levels when the appropriate equipment is available. If the patient is in obvious respiratory distress, the practitioner should attempt to perform ventilation using a bag-valve mask device, and then contact emergency medical services immediately. Placement of a nasal trumpet is warranted, especially if ventilation with a bag-valve mask device is difficult.

Securing the airway. The clinician should perform direct laryngoscopy, when indicated, with either oroendotracheal or nasoendotracheal intubation. If direct laryngoscopy is not successful, the clinician should attempt another means of securing the airway, such as placing a laryngeal mask airway or twin lumen device (Combitube, Kendall Sheridan, Argyle, N.Y.).⁹ If the above attempts fail to secure the airway, the clinician should perform an emergency cricothyrotomy. A tracheostomy should be performed only by an experienced surgeon in the operating-room setting.

Authors of published cases have reported intervention ranging from simple bimanual digital compression to extraoral approaches to the lingual artery.^2–11 Initially, the clinician should use digital compression to tamponade the source of hemorrhage. Aspiration or drainage may not be a good approach to aid in resolution of the hematoma, may increase the amount of bleeding and may limit the chance that the hematoma may tamponade itself.⁵ Close inspection of the surgical field should include careful examination of the lingual cortex through a lingual subperiosteal approach. Obvious sources of hemorrhage should be ligated or cauterized.

If the patient’s condition continues to deteriorate, the clinician must decide quickly whether surgical intervention and exploration likely are needed, and make arrangements for the patient’s rapid transport to a hospital. The dentist should consult immediately with a surgeon qualified in neck dissection. Physicians in interventional radiology also should be consulted, and angiography should be performed to help locate the source of hemorrhage. If an interventional radiologist identifies the source, he or she should attempt to perform embolization. If the source cannot be identified by the interventional radiologist or embolization fails, a surgeon should perform surgical exploration as a last resort.

Although ligation of both the facial and lingual artery has been reported, practitioners more commonly attempt to ligate the lingual artery first because of its location.² However, Bavitz and colleagues¹⁶ conducted a cadaveric study, the results of which showed that the submental artery can be considered the main arterial blood supply to the floor of the mouth. The sublingual artery was small, missing or insignificant in 53 percent of cases.¹⁶ The authors concluded that the submental artery or its parent facial artery should be ligated first. If this fails to control the bleeding, the surgeon then should ligate the lingual artery. Niamtu⁹ concurred with these findings. Burke and Masch⁶ described the extraoral approach to ligation of the lingual artery, which involves identification of Lesser’s triangle.

If the clinician decides that surgical intervention is not appropriate, he or she should admit the patient to the telemetry unit of a hospital for a minimum of 24 hours of observation. The patient should be monitored closely for changes in the size of the hematoma or for ensuing airway compromise. During the hospital stay, physicians from the medical service should evaluate the patient for any underlying coagulopathies.

If the hematoma remains static and the patient is in stable condition, he or she may be discharged from the hospital if close medical follow-up can be arranged. The practitioner who performed the implant surgery should conduct appropriate postoperative imaging studies, including panoramic radiography and lateral cephalography, to evaluate implant placement.

	CONCLUSION

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Although implant placement in the edentulous anterior mandible is a common procedure, it is not without risk. Clinicians need to inform patients of the potential complications, and surgeons should be well-versed in the treatment of a sublingual hematoma. Before the procedure, clinicians should consider the patient’s anatomy to determine if he or she is a good candidate for implants, as well as determine the correct implant length. Early recognition and treatment of the sublingual hematoma should result in a favorable prognosis for the patient.

View larger version (110K): [in this window] [in a new window]   Dr. Isaacson is a resident, University of Minnesota, School of Dentistry, Division of Oral and Maxillofacial Surgery, Room 7-174 Moos Tower, 515 Delaware St. S.E., Minneapolis, Minn. 55455, e-mail "isaa0089{at}tc.umn.edu". Address reprint requests to Dr. Isaacson.