This article generally describes the most common pathogenic microbes in the oral cavity, the most common odontogenic infections, treatment and possible complications.
Odontogenic infections are infections that originate in the teeth and/or their supporting tissues. These infections are common, and a large proportion of infections of the head and neck region are of odontogenic origin. Odontogenic infections cause mild signs and symptoms, but can also develop into serious conditions.
| Causative microbes |
The oral cavity contains more than 700 natural species of bacteria.
One of the most widespread bacterial genera in the oral cavity is streptococcus. Common species include S. mitis , S. sanguinis, S. salivarius, and S. anginosus, which may contribute to the development of caries, marginal periodontitis, and endocarditis. Bacteria in the oral cavity are opportunists that can cause infection if the interaction between the host and the microbe changes.
In the early phase of an infection, the causative microbes will reflect the normal flora of the oral cavity, but as the infection progresses, anaerobic species will normally predominate. In addition to causing local infections in bones and soft tissues, oral bacteria may contribute to the development of Alzheimer’s disease, endocarditis, atherosclerosis, osteomyelitis of non-craniofacial bones, rheumatoid arthritis, and diabetes mellitus. Studies have also shown that maternal apical and marginal periodontitis may be associated with low birth weight newborns.
| Typical bacterial odontogenic infections |
> Marginal periodontitis
Gum disease called marginal periodontitis is an inflammatory condition that affects the periodontium, the supporting tissue of the teeth. Studies have shown that almost 50% of adults in the US have marginal periodontitis and in Oslo, 8% of 35-year-olds have advanced periodontal destruction.
The association between marginal periodontitis and diabetes is well documented; Patients with either condition are at higher risk of developing the other. Studies have shown that there is also an association between marginal periodontitis and cardiovascular disease but there is currently insufficient evidence to indicate a causal relationship.
Marginal periodontitis is caused by the buildup of biofilm (plaque) along the gum line. This results in a superficial infection of the gum (gingivitis) which can lead to a deeper infection along the root of the tooth (marginal periodontitis). The condition is progressive and can eventually cause the loss of the affected teeth. Smoking, diabetes and stress are known risk factors.
The treatment of marginal periodontitis is performed by dentists or dental hygienists and consists of the mechanical removal of plaque and tartar. In some cases of aggressive periodontitis, antibiotics are indicated.
> Apical periodontitis
The root canal is essentially a sterile closed system.
However, bacteria can enter the canal through cavities, fractures, cracks between a filling and a tooth, and periodontal pockets. The subsequent immune response with recruitment and activation of leukocytes leads to inflammation of the dental pulp (pulpitis), which can be very painful.
If left untreated, bacteria can invade the dental pulp and cause necrosis. Infection of the dental pulp, in turn, leads to inflammation of the periodontal ligament, and bacterial products can exit the root canal through the root apex. The subsequent immune response will lead to inflammation and destruction of the periapical tissue, called apical periodontitis, a condition that is usually asymptomatic. However, the production of pus can lead to the formation of a periapical abscess. This generally causes pain, swelling, and occasionally fever.
Periapical infections can also spread to neighboring structures. Drainage of pus through a fistula (extraoral or intraoral) will reduce symptoms. The pus from acute periapical abscesses must be drained quickly, either through the root canal or through an incision. The procedure is mainly performed by dentists.
> Pericoronitis
Pericoronitis is an infection that begins in the soft tissue around partially impacted teeth (teeth left in the jaw).
The condition occurs primarily in young adults and typically affects the wisdom teeth in the lower jaw, when food debris and other foreign material accumulates between the gum and the partially erupted crown of the tooth. Typically, this leads to a recurrent low-grade infection with pain, swelling, and redness in the surrounding gum. In some cases, patients may also have trismus , fever, and general malaise.
Predisposing factors are stress, menstruation and a recent or current illness. Generally, pericoronitis is self-limiting, but recurrence is common until the tooth erupts or is extracted. In some cases an abscess may also form, requiring incision and drainage. In most cases, teeth with recurrent pericoronitis should be extracted during an inactive phase of the infection.
| Other bacterial infections with possible odontogenic etiology |
> Odontogenic sinusitis
Up to 40% of maxillary sinusitis are of odontogenic origin.
The most common causes of odontogenic maxillary sinusitis are apical periodontitis, marginal periodontitis and oroantral fistulas after extraction of upper molars. The condition typically causes pain, mucosal edema, and a runny nose. Unlike maxillary rhinogenic sinusitis, odontogenic sinusitis is usually unilateral. Treatment consists of eliminating the focus of dental infection, with elective functional endoscopic sinus surgery, if indicated. If sinusitis is caused by a persistent oroantral fistula after tooth extraction, the fistula can be closed surgically by a specialist in maxillofacial surgery (medical specialty) or oral surgery (dental specialty).
> Osteomyelitis
If the infection has spread to the cortical and cancellous bone, the origin of acute purulent bacterial osteomyelitis may be infection of the teeth and periodontium. The lower jaw is affected more frequently and patients usually present severe pain, fever, pus secretion in the area, trismus and halitosis, due to the presence of anaerobic bacteria. If the inferior alveolar nerve is affected, there may be paresthesia or hypoesthesia of the lower lip and chin. With delayed treatment, acute osteomyelitis can become a chronic disease.
Chronic osteomyelitis usually has milder symptoms than the acute form and is characterized by sequestration and possibly fistula. Computed tomography (CT), panoramic dental radiography, and magnetic resonance imaging can reveal varying degrees of osteolysis, osteosclerosis, and sequestration. Treatment consists of antibiotics, drainage of any abscesses, and possibly surgical revision by an oral or maxillofacial surgeon with removal of infected, necrotic tissue. The original focus of the infection must also be treated, for example, through endodontics, therapy or extraction of one or more teeth.
> Necrotizing fasciitis
Necrotizing fasciitis is a serious, destructive and progressive soft tissue infection, which can quickly become life-threatening.
The disease is divided into two subtypes depending on the causative bacteria. Type 1 is caused by streptococci (non-group A), enterobacteria, or obligate organisms and anaerobes. Type 2 is caused by group A streptococci.
The condition begins with thrombosis in small blood vessels, on the periphery of the focus of infection, leading to acute inflammation and edema in the subcutaneous tissues and, possibly, the skin. Necrosis then occurs in the infected tissue. This spreads rapidly along the superficial fascia, nerves, arteries and veins. If left untreated, most patients will develop sepsis within 48 hours.
Due to its rich vascular supply, necrotizing fasciitis rarely occurs in the head and neck area, with an annual incidence of only 2 cases/1,000,000 population. The most common cause of necrotizing fasciitis in the head and neck area is an odontogenic infection, but the condition can also occur secondary to pharyngitis, tonsillitis, acute otitis media, and infectious dermatological diseases. If an odontogenic origin is suspected, the patient should be immediately referred to a maxillofacial surgery department or, alternatively, to the nearest otorhinolaryngology or plastic surgery department.
Contrast-enhanced CT is necessary to determine the location and extent of infection, as well as to reveal any primary focus, for example, periapical radiolucent areas in the roots of the teeth. On the other hand, contrast-enhanced CT may show asymmetrical fascial thickening, gas bubbles along the fascial planes, edema of the muscles and soft tissues, and possibly fluid accumulation in the fascial spaces, indicating an abscess.
It is important to implement prompt treatment with radical surgical debridement of necrotic tissue and administration of antibiotics. Norwegian national guidelines recommend combined treatment with cefotaxime and metronidazole, with the addition of clindamycin, if indicated.
> Ludwig’s angina
Ludwig’s angina is a rapidly progressive infection of the submandibular and sublingual spaces.
The infection does not usually cause abscesses but is phlegmonous and spreads diffusely to both sides of the floor of the mouth. Patients usually have general malaise, fever, and pronounced submandibular swelling. The tongue may be swollen and pushed out of the mouth, into the retropharyngeal space or against the palate, leading to upper airway obstruction. The infection can also cause airway obstruction. by extending to the lateral compartment of the neck or the retropharyngeal space.
If left untreated, the condition has a mortality rate of around 50%, requiring vigilance regarding airway protection. Therefore, patients should be urgently referred to a hospital with a maxillofacial surgeon or otorhinolaryngologist.
The most common causes of Ludwig’s angina are odontogenic infections of the lower second and third molars, because their roots are caudal to the mylohyoid muscle. Other triggering factors are peritonsillar or parapharyngeal abscesses, infection secondary to a mandibular fracture or submandibular sialadenitis. To determine the extent of the infection and the presence of an abscess, CT with intravenous contrast is recommended. Prompt diagnosis is important to allow immediate initiation of antibiotic therapy along with incision and drainage in cases of purulent infection. Some also recommend the use of systemic steroids.
| Lemierre syndrome |
If the odontogenic infection spreads dorsolaterally to the lateral neck compartment, the result may be septic thrombophlebitis of the internal jugular vein. The condition is rare, with a reported annual incidence of 3.6 cases/1,000,000 population. However, the number of published case reports is increasing, probably due to increased awareness of the condition as well as better diagnostic imaging. The syndrome most often affects previously healthy children and young adults.
The most common etiology is a recent episode of viral pharyngitis . This likely compromises the mucosal barrier, leading to migration of bacteria to deeper tissues. As the most common causal agents, opportunistic gram-negative bacilli in the form of fusobacteria have been described, but up to a third of cases are polymicrobial. Septic embolization occurs in most cases, most commonly in the lungs and large joints, but septic emboli have also been reported in the brain, skin, liver, and pericardium.
In addition to the signs and symptoms resulting from any embolization, patients typically have neck pain, fever, trismus , a palpable mass corresponding to the internal jugular vein, and positive blood cultures.
Treatment consists of long-term antibiotic therapy, which has improved the prognosis, from a mortality rate of 90% in the preantibiotic era to less than 18% in modern times. The use of anticoagulation is controversial. Depending on the etiology, cases of Lemierre syndrome should be discussed with a maxillofacial surgeon or an otorhinolaryngologist.
> Spread of infection to the deep cervical fascial compartment
The spread of the infection to the deep spaces of the neck can have serious consequences. There are at least 11 deep spaces in the neck defined by various fasciae of the face and neck. Most deep cervical infections result from the spread of primary odontogenic infections. Extension follows the path of least resistance along the fascia and can lead to the formation of cavernous sinus thrombosis, brain abscess, meningitis, mediastinitis or pericarditis.
Signs and symptoms depend on the location of the infection. They may include fever, malaise, swelling, odynophagia, dysphagia, hoarseness, stridor, and trismus . The swelling can cause compression of the trachea, which can threaten airway patency. Contrast-enhanced CT can reveal both the location of the infection and its phlegmonous nature or the formation of an abscess.
Timely antibiotic therapy is important, along with surgical drainage of pus, if indicated. Like Lemierre syndrome, the etiology determines where treatment takes place.
| Conclusion |
Uncomplicated local odontogenic infections are common and can generally be managed by a dentist. In some cases, odontogenic infections can develop into serious conditions. Therefore, it is important to be aware of these conditions and refer any suspected cases to hospitals with experience in maxillofacial or otorhinolaryngological surgery.
