Life-threatening complications of dental implant surgery are rare, but include hematoma/hemorrhage of the floor of the mouth, aspiration, and ingestion. Prevention of lethal hemorrhagic complications stem from knowledge of anatomic structures and precise surgical planning. Prevention of aspiration and ingestion can be improved by simple techniques while understanding clinical settings and factors that put patients at higher risk. In the event of these potential lethal situations, early recognition of signs and symptoms along with immediate action followed by transfer to an emergency department is often necessary.
Key points
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Life-threatening complications of dental implants are hematoma, hemorrhage of floor of the mouth, aspiration, and ingestion.
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The key to preventing hemorrhagic complication is knowing anatomic structures relevant to the implant position and proper planning.
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Aspiration and ingestion can be better prevented by understanding clinical settings and patient risk factors.
Introduction
Ever since the discovery of dental implants, its surgery has become more prevalent and now routinely done in a clinical setting due to its high success rate and safety. Although many methods and technological advances have emerged in the recent decades, complications still occur as described in previous chapters (periimplantitis, mucositis, infection, nerve damage). Although unfortunate, these complications often do not pose lethal consequences. These adverse outcomes are often preventable and are typically able to be managed in a clinical setting. Despite being uncommon, life-threatening complications can occur in some situations. Such emergencies include hemorrhage/hematoma formation of the floor of mouth, aspiration, and ingestion of foreign bodies, that is, implant parts. These complications can happen during routine dental implant surgery and can cause lethal events such as airway obstruction, perforation of organs, and infection. Management of these life-threatening conditions can be more challenging and have life altering consequences to the patient in addition to both legal and financial loss to the practitioner. It is crucial for clinicians to be able to promptly recognize life-threatening emergencies and take appropriate measures. With pertinent preparation, knowledge of anatomic structures, and preventative protocols, these adverse events can be prevented.
Hemorrhage/hematoma in the floor of the mouth
One of the common complications in implant surgery is hemorrhage. Minor bleeding is frequently encountered during and after the procedure and is relatively well managed with local measures in a clinical setting. However, significant hemorrhage and hematoma formation in anterior mandible can be life threatening, as it can lead to airway obstruction. In general, the incidence of severe implant related hemorrhage was found to be ∼ 24%. Reported causes included soft tissue damage, violation of arteries, and osteotomy perforations. Regarding the site of injury, life-threatening consequences via airway obstruction originated more commonly from bleeding in the anterior mandible compared with other parts of the mouth. This is due to perforation of the lingual cortex causing vascular injury within soft tissue.
The lingual aspect of the anterior mandible has a rich vasculature as it is supplied by the sublingual, submental, and incisive arteries. These arteries also supply the muscles and soft tissues of the floor of the mouth. The sublingual artery originates from the lingual artery, anastomosing with the submental artery that branches from the facial artery. These arteries run along the lingual side of the anterior mandible parallel to the mylohyoid muscle. In most of the cases (80%–90%) sublingual arteries run through the lingual foramen in the midline, penetrating through the lingual cortical plate. These vessels anastomose with the incisive arteries that are branches of the inferior alveolar artery These vessels together form a highly vascularized network in the lingual aspect of mandible ( Fig. 1 ). Damaging vessels in this area during implant surgery can cause significant hemorrhage with blood loss rate of 14 mL/min. This bleeding can spread through the loose adipose and connective tissues of the floor of the mouth to involve facial spaces such as sublingual, submental, and submandibular spaces. As this hemorrhage worsens, it can cause posterior displacement of the tongue. This will apply direct pressure against the soft palate into the pharynx, leading to rapid upper airway obstruction. , In such circumstances, often aggressive airway management may be necessary. Law and colleagues found that in 25 reported cases, lingual cortex perforation was the most common cause of severe hemorrhage, resulting in 68% of patients requiring intubation or tracheostomy due to airway obstruction. Therefore, knowing key anatomic structures in the anterior mandible combined with precise surgical planning is crucial to preventing life-threatening consequences.
Management
The definitive procedures to control airway obstruction due to severe hemorrhage/hematoma in the floor of the mouth are limited in a dental office setting. Initial recognition of such symptoms should prompt the clinician to consider transfer and immediate airway management. Clinical findings of hemorrhage progressing to airway obstruction may present with evident bleeding in the oral cavity, severe pain, protrusion of the tongue, bruising, and swelling of the floor of the mouth. The patient can show symptoms of dysphagia, dyspnea, and cyanosis with inadequate oxygen saturation, eventually resulting in respiratory arrest.
Local hemostatic measures are crucial; however, initial treatment options are limited in an ambulatory clinic in the event of severe hemorrhage in the floor of the mouth. In such event, one should immediately terminate the surgical procedure and apply direct pressure. Bimanual compression inferiorly at the floor of the mouth and lingual surface of the mandible in conjunction with upward force against the submental region is recommended. The goal is to decrease bleeding and expansion of the hematoma to ultimately prevent airway obstruction. In addition, compression with ice can aid in hemostasis. Hemostatic agents such as resorbable gelatin sponges, oxidized cellulose, or bovine collagen plugs combined with pressure can be applied to osteotomy and/or extraction sites. If available, electrocautery can aid in hemostatic efforts. If hemorrhage/hematoma expansion remains uncontrolled or signs of airway obstruction are present despite attempting local measures, activate 911 response and rapid transport to the nearest hospital emergency department. Meanwhile, vital signs should be monitored and oxygen may be supplied through nasal canula to lessen dyspnea stress. Moreover, efforts should be made to reduce patient anxiety to prevent further bleeding due to hypertension. Endotracheal intubation or tracheostomy may be required if the patient is unable to breath adequately, demonstrating signs of oxygen desaturation.
Emergency evacuation of the hematoma can be considered if the clinician is adequately trained to do so. However, an inexperienced practitioner attempting this procedure can worsen the bleeding and create more soft tissue destruction. Moreover, experienced clinicians can attempt to ligate the damaged vessel. Studies suggest that ligating the facial or sublingual artery can control floor of the mouth hemorrhage. If unsuccessful, ligation of the lingual artery can be attempted. However, without adequate anesthesia or specialized training, attempting to ligate the damaged vessel might worsen the situation due to multiple anastomoses of nearby arteries and a limited visual field in an office setting. Hence, prompt transport to an emergency department is crucial as definitive treatment involves airway management and complex operations that require the expertise of a skilled surgeon. If direct intraoral approach is unsuccessful, angiographic e-embolization or ligation of the carotid artery via extraoral approach can be considered in conjunction with using vascular angiography or computed tomographic (CT) scans.
Prevention
Severe hemorrhage in the floor of the mouth can put the patient’s life at risk, requiring invasive treatment. The importance of using preventive measures cannot be overemphasized. One of the simple and easy preventive methods is obtaining a preoperative cone-beam computed tomographic (CBCT) scan. Compared with conventional 2-dimensional radiographs, CBCT is superior, as it can reveal the position and diameter of intrabony vascular canals that may contain significant vessels, especially in anterior mandible. This can be advantageous to the clinician in avoiding or preparing to control any incidental arterial hemorrhage during implant placement. In the studies of 25 reported cases of hemorrhage, most of the bleeding was caused by lingual cortex perforation. Only one case used preop 3-dimensional imaging before implant placement. This demonstrates the importance of obtaining preop CT. In addition, CBCT allows one to visualize mandibular atrophy and its angulation. This encourages ideal implant position by engaging more bone, leading to better primary stability while avoiding perforation of the lingual plate, protecting sublingual soft tissue.
Injecting local anesthesia multiple times in anterior mandible, especially it the lingual aspect, is suboptimal, as it can cause bleeding from nicks in vessels that do not cease spontaneously. These local injections with a vasoconstrictor can delay the symptoms of a hematoma of the floor of the mouth. Therefore, inferior alveolar nerve blocks are preferred to avoid direct damage to vessels in that region.
Favoring a narrower diameter implant in anterior mandible can be another method to prevent hemorrhagic complications. The occlusal load of the anterior mandible is one-third of the posterior and generally has a bone dense enough to resist occlusal forces. The clinician can opt for narrow diameter implants that can be placed a few millimeters away from the midline to possibly avoid a single large sublingual artery.
In patients with severely angulated and/or atrophic mandibles, there is an increased risk of perforating the lingual cortical plate, which is in close vicinity to a vascular plexus that has great potential to cause severe bleeding. Avoiding lingual subperiosteal tears is of utmost importance, as its injury can lead to detrimental bleeding, as the main vascular osseous supply of the anterior mandible is provided by the facial artery via periosteal vasculature in the atrophic mandible. Injury of mandibular lingual vascular canals itself is less concerning due to their small diameter. CBCT and surgical stents can decrease the chance of perforating the lingual cortical plate by encouraging correct implant positioning. In addition, digital palpation on the lingual mandible should be applied for tactile feedback to avoid perforation while gently advancing the bur. Furthermore, lingual subperiosteal flap enhances visualization to prevent lingual perforation. On the contrary, some claim that flapless implant placement in the anterior mandible may have fewer complications compared with open flap procedures. However, if excessive bleeding occurs while using the flapless technique, blood can expand into the floor of the mouth and deep neck region rather than draining into the oral cavity. Therefore, manual palpation of the lingual mandible in conjunction with proper preop planning of implant position with CBCT should be considered.
Aspiration and ingestion
Aspiration and ingestion of instruments and/or materials can occur during any stage of implant surgery and may lead to life-threatening consequences. The foreign object can be either aspirated or swallowed, depending on the route taken beyond the pharynx. It is evident in the literature that aspiration was observed more often during implantation, prosthodontics, and restorative dentistry, whereas prosthodontics and root canal treatment was more related to ingestion. In general, aspiration or ingestion is an infrequent occurrence, the latter happening more often as a direct result of the strong coughing that occurs when there is a foreign object in the patient’s airway. Although aspiration has lower incidence, it poses a higher risk for lethal complications, as an aspirated object can lead to acute airway obstruction and lung infections including abscess formation or pneumonia. Similarly, an ingested foreign object can also be life threatening, as objects can become entrenched through its passage through the gastrointestinal (GI) tract and lead to severe inflammation, obstruction, and infection.
There are various risk factors related to a patient’s medical history in addition to modifiable clinical factors that can facilitate aspiration and ingestion of a foreign body during implant surgery. Patients with psychological disorders, mental retardation, excessive gag reflex, alcoholism, small oral cavity, and macroglossia; those who are obese or pregnant; and the elderly should be considered at higher risk for complications. In a clinical setting, the patient’s risk of aspiration and ingestion of foreign objects may also be increased by local anesthesia, supine positioning, inadequate lighting, ineffective assistants, and airway protection. Evidently, these complications can be detrimental to the patient but can also create potential for legal action against the clinician and related economic costs. Thus, it is crucial to thoroughly evaluate a patient’s medical history for aspiration/ingestion risk factors and be mindful of adjustable clinical settings to prevent complications.
Symptoms
The symptoms of aspiration and ingestion can be varied. In general, patients commonly present with coughing, gagging, and dyspnea following aspiration of a foreign body. If larger objects are aspirated, immediate airway obstruction is possible, which can present as inspiratory stridor, paradoxic breathing, and cyanosis with inadequate oxygen saturation. On physical examination, one may notice tachypnea, tachycardia, stridor, unilateral or bilateral decreased breath sounds, localized wheezing, and/or crackles. It is possible for a patient to not present with any initial discomfort or symptoms. However, even asymptomatic patients who had potentially aspirated a foreign body, necessary protocol should be taken, because chronic retention of foreign bodies in the airway can manifest as serious consequences including infection, pneumothorax, vocal cord paralysis chronic cough, hemoptysis, pneumonia, unexplained fever, and even death.
In contrast, patients with ingested foreign bodies are often asymptomatic. Nevertheless, signs and symptoms can still develop, commonly presenting as coughing, gagging, dysphagia, odynophagia, cramps, nausea, and vomiting. In the event of an asymptomatic patient who has ingested foreign body, adequate treatment protocol is still necessary, as complications can progress to bowel obstruction, infection, and perforation.
Management and Prevention
Consequences of aspiration and ingestion may lead to lethal complications that require invasive treatment, and thus prevention is key. A simple yet important preventative technique is applying a gauze screen. Often times, the practitioner negates this method for various reason; however, there is no superior way to prevent accidents. The gauze screen should be applied posterior to the surgical site to block entry of a foreign body passing the oropharynx. Tying floss or sutures to small instruments such as an implant screwdriver can prevent aspiration and ingestion, as it provides the clinician a fast way to retrieve the fallen object. In addition, controlling variables such as inadequate lighting, the lack of assistance, or proper instrumentation such as high-speed suction should be addressed before any implant-related procedure. This becomes crucial especially when placing implants in posterior regions where visibility and accessibility can be compromised. Controlling chair position can be advantageous especially when patients have an unfavorable gag reflex and are unable to tolerate a gauze screen. In this circumstance, patients seated upright with their head turned sideways is beneficial. Also, adequate suction to evacuate excessive saliva and blood can help reduce the gag reflex, leading to unpredictable movements.
If an object is lost beyond the oropharynx while in a supine position, the patient should be kept supine, turned to their right side, and attempt to “cough up” the foreign body. Slow inhalation followed by a forceful cough can minimize aspirating the object deeper. Because the adult right bronchus diverges at a more acute angle from the trachea compared with the left side and also has a greater diameter than the left bronchus, the right side is the more common path for aspirated objects ( Fig. 2 ). , This right-sided Trendelenburg positioning decreases the effect of gravity pushing the foreign body deeper while helping keep the aspirated object to the right mainstem bronchus. Spontaneous or endoscopic retrieval is easier in the right mainstem bronchus, as its diameter is wider and provides a straight passage. If aspiration occurs while the patient is upright, the patient should be lowered to the favored right-sided Trendelenburg position, unless they are violently coughing. In contrast, there are conflicting views, as some experts believe that the patient should be placed into reverse Trendelenburg position before being encouraged to cough. They believe this maneuver may aid in regurgitating the foreign body. Regardless, if the object is visible, the clinician may use forceps or high-volume suction to retrieve the object while being careful not to dislodge it further. Immediate action must be taken to prevent respiratory failure if the patient shows signs of airway obstruction such as choking, dyspnea, stridor, and using accessory muscles to breathe. In this instance, abdominal thrusts in conjunction with finger sweeps and suction can be performed. If unsuccessful, cricothyroidotomy may be considered by emergency personnel while the patient is being arranged for immediate transfer to the closest emergency department. It is also important to reassure asymptomatic and stable patients who have aspirated or ingested foreign body that the situation is manageable. At the same time, patients must seek immediate medical attention and determine whether the object was aspirated or ingested by taking a series of radiographs of the abdomen and chest. The treatment modality depends on the location of the foreign body.
