Dental Infections

Etiology

Dental Caries

Dental caries result from the interaction between the tooth structure, the dental plaque on the tooth surface, and fermentable carbohydrates. Salivary and genetic factors also influence the development of dental caries.[4]

The biofilm bacteria metabolize fermentable carbohydrates (glucose, fructose, sucrose, and maltose) from the diet, producing organic acids, mainly lactic acid. These end products of bacterial metabolism decrease the pH and demineralize the dental structure's outer layer. After the sugars are cleared by swallowing and saliva dissolution, the acids are neutralized by the buffer capacity of the saliva, and the biofilm pH returns to neutrality. The biofilm is now saturated by calcium, phosphate, and fluoride ions, stopping demineralization and favoring the remineralization of the dental surface.[4] This process happens every time sugars are ingested, explaining why individuals with a reduced salivary flow are at increased risk of dental caries. However, if acidic conditions prevail due to frequent sugar consumption, there is a shift in the biofilm microorganisms to more acidogenic and cariogenic bacteria. The rate of mineral loss is higher than the deposition of minerals, resulting in the first clinical sign of the disease, the 'white spot,' also known as an incipient lesion.[4]

It is worth noting that white spots are reversible carious lesions that can be remineralized by non-invasive procedures like fluoride application and behavioral changes, such as improving dental hygiene and decreasing sugar intake. Hence, early referral to a dentist is vital if these lesions are discovered during a clinical examination. By contrast, if incipient lesions are not managed, they will gradually progress to microcavities in the enamel, collapsing and leaving a macroscopic cavity.[4]

Pulp Involvement

Pulpitis is the inflammation of the dental pulp, which can be caused by bacterial by-products reaching the pulp from dental caries, bacteria entering the pulp through the apical foramen from a periodontal infection, or through a tooth fracture.[5] Furthermore, traumatic and chemical insults can also result in pulpal inflammation.[6] The early stage of pulpitis elicits mild intermittent dental pain, typically triggered by thermal stimuli, like cold drinks, but without spontaneous pain. This is known as reversible pulpitis, and treatment involves the removal of the carious tissue and placing a restoration.

The dental pulp can be irreversibly damaged due to persistent inflammation, leading to constant, spontaneous, acute dental pain, which is poorly localized. Irreversible pulpitis is one of the main reasons for patients presenting to the emergency department.[7] Irreversible pulpitis must be referred to a dentist, as the standard of care is partial or complete pulp removal.[6]

Antibiotics are not indicated in managing irreversible pulpitis as signs of infection, such as swelling of the adjacent mucosa, do not normally accompany it.[7] There is limited evidence that antibiotics reduce symptoms of dental pain or the number of analgesics used in untreated teeth with irreversible pulpitis.[8] Hence, antimicrobials are not prescribed before referral. Ultimately, irreversible pulpitis may lead to ischemia and pulp necrosis, where the tooth is asymptomatic.

An apical abscess can further complicate pulp necrosis. Apical abscess, dentoalveolar abscess, and odontogenic abscess are usually used interchangeably to describe the localized collection of pus around the periapex due to the spread of infection of the root canal.[9] Two forms of periapical abscess can develop: acute or chronic.

Patients with an acute apical abscess report mild to severe pain and swelling. The tooth is usually extremely sensitive when touched or tapped with an instrument (percussion). In most cases, the swelling develops intraorally. Systemic symptoms may develop, including fever, fatigue, and lymphadenopathy. In the maxilla, acute apical abscesses drain through the buccal or palatal bone plates into the buccal cavity. In the mandible, they may drain buccally or lingually into the oral cavity or spread into the fascial spaces of the neck, leading to cellulitis and potentially severe complications.[9] Apical abscesses in the mandibular molars can extend to the sublingual, submandibular, and submental spaces. This condition is known as Ludwig angina, a life-threatening condition that obstructs the airways if not managed in time.[10]

An apical abscess is usually a localized infection that does not require antimicrobials before referral to the dentist.[5] Antibiotics are only indicated when there are signs of systemic spread of the infection, eg, fever or cellulitis.[5] A broad-spectrum antibiotic is most commonly prescribed, usually amoxicillin/clavulanate.[11] Treatment of acute apical abscess includes drainage of the tooth, endodontic treatment to remove the necrotic pulp, and restoration of the affected tooth. Alternatively, the offending tooth is extracted.

Periodontal Disease

Periodontal infections first involve the gingival tissues, causing gingivitis, which may evolve into periodontitis in susceptible individuals. Periodontal disease results from poor dental hygiene, accumulating plaque and calculus, and subsequent inflammation of tissues surrounding and supporting the teeth: gingivae, periodontal ligament, and alveolar bone. The etiology of periodontitis is multifactorial. While bacteria initiate it, the clinical presentation and outcome of the different forms of the disease are determined by the inflammatory response and modifying and predisposing factors. The main risk factors for periodontal disease include tobacco smoking and diabetes mellitus. The disease progression seems regulated by environmental and genetic factors specific to each patient.[12]

Epidemiology

It is estimated that 13% of adults seek dental care for dental infection or toothache within four years and that 1 per 2600 heads of the population in the United States is hospitalized due to dental infections.[13][14] More than 1 in 5 people have untreated dental caries, and 3 in 4 had at least one dental restoration. Periodontitis is also common, with estimations that 35% of all Americans aged 30 to 90 are afflicted.[15]

More than 1 in 5 people have untreated dental caries, and 3 in 4 had at least one dental restoration. Periodontal disease is also common, with estimations that 35% of Americans aged 30 to 90 are afflicted.[15]

Furthermore, the prevalence of dental caries varies significantly by socioeconomic factors. Untreated dental caries were more than 2.5 times as common in those living 100% below the poverty level (41.9%) relative to those living 200% above the federal poverty level or higher (16.6%). The prevalence of dental caries is also dynamic during the patient's lifetime. Dental caries are present in 90% of adults and 42% of children ages 6 to 19.[16] Dental caries did not appear to vary much with age, except that adolescents aged 12 to 19 were found to have a lower rate of untreated dental caries even when compared to children aged 5 to 11.

History and Physical

Dental Caries and Dental Pulp State

Caries can be acute or chronic, brown-yellow, and soft or black and hard cavities. Pulp exposure may be seen. Incipient caries are more challenging to identify and represent the first clinical manifestation of caries. They are white and opaque irregular spots that may appear on any tooth surface and are more prevalent in plaque stagnation areas, such as the union of the gingival tissue and the tooth surface.

Patients with reversible pulpitis present with toothache induced by stimuli like hot or cold drinks or foods. Irreversible pulpitis presents as unprovoked tooth pain that usually exacerbates overnight. A periapical abscess may present as a palpable swelling. A dental abscess can originate from the pulp, periodontal structures, or both. More serious complaints such as fever, facial edema, trismus, dysphagia, or dysphonia can be symptoms of a more serious dental infection that has extended into deep neck spaces. Patients may be in respiratory distress or hemodynamically unstable with sepsis.[17]

Periodontal Disease

Patients with gingivitis and periodontitis will often present with a history of halitosis and bleeding after brushing their teeth. It is noteworthy that pain is not associated with periodontal diseases, except necrotizing periodontal disease.

Gingivitis is the localized inflammation of the gums mainly caused by the accumulation of dental plaque on teeth. Clinically, it is characterized by swollen, erythematous gums, which tend to bleed.[18] In gingivitis, there are no periodontal pockets (pathological deepening of the gingival sulcus).[19]

Periodontitis involves the apical migration of the junctional epithelium and the development of periodontal pockets. According to the degree of destruction, clinical findings of periodontitis may include gingival recession, dental papilla detachment, loss of alveolar bone (visible on radiographs), tooth mobility, or fremitus.[20]

Evaluation

Depending on severity, dental infections can be further evaluated using dental radiographs, orthopantomography, CT scans, and MRIs. Imaging studies play an essential role in recognizing the source of infection and the proportions of the disease spread and also can detect any complications. The most common x-rays used in dentistry are orthopantomography and intraoral x-rays, including periapical and bitewings. These are usually sufficient to assess the extent of a dental infection. Cone-beam CT (CBCT) is useful in determining periapical disease, pericoronitis, and osteomyelitis. CT with contrast can help evaluate the extent and severity of fascial space infections. However, the first step in managing patients presenting with signs of fascial space infections, like breathing difficulty, is securing the airways via flexible nasotracheal intubation or tracheotomy. After the airways are secured, further imaging examination may be done.

Laboratory studies, including complete blood count, may be helpful in patients with more severe presentations. Patients with facial or deep space infections may present with sepsis and warrant the addition of blood cultures and lactic acid levels.[21]

Treatment / Management

Management of Patients Presenting with Dental Pain

Patients with odontogenic infections often present to the emergency department due to dental pain, usually caused by pulpitis or acute periapical abscess. Patients must be evaluated for signs of spread of infection beyond the oral cavity and systemic compromise to rule out the need for emergency management. If there is any suspicion of airway compromise, patients must be transferred to an emergency department where the airway can be managed, and the oral and maxillofacial unit must be informed.[22] Red flag symptoms suggesting that a worsening swelling may require emergency management include significant trismus (difficulty to open the mouth), swallowing difficulty, drooling, restricted tongue mobility, firm or swollen floor of the mouth, and a 'hot potato' voice.[23] Patients with Ludwig angina require hospital admission, airway management, and intravenous antibiotics.[23]

Patients should be referred to a dental practitioner for further management if emergency treatment is not indicated.[22] The standard of care for dental infections is surgically controlling the infection source.[22] Definitive treatment can only be administered by a dental practitioner. If the pain is caused by irreversible pulpitis, the treatment is root canal therapy. When the pain results from an acute periapical abscess, the initial management is done by draining through the swelling or the affected tooth by creating an opening on the occlusal surface and then either eliminating the pulp and infection of the root canal with a root canal treatment or extracting the tooth if it is deemed unrestorable.

When to Prescribe Antibiotics

Antibiotics play a secondary role in the management of dental infections. They are only prescribed as adjuvants to surgical treatment when patients show signs of local or systemic spread of infection, including cellulitis, fever, lymphadenopathy, or fatigue. In this case, antibiotics can be prescribed before referral.

Dental infections are polymicrobial, caused by a mixture of anaerobic and aerobic bacteria.[22] The selected antimicrobial must target these bacteria. For outpatients, combining penicillin, usually amoxicillin, with a beta-lactamase inhibitor provides appropriate coverage.[1][22] An alternate antimicrobial is metronidazole, which has improved pharmacokinetics and is better tolerated than erythromycin. Metronidazole is indicated as a first-line treatment when patients are allergic to penicillin, received penicillin recently for another infection, or if the infection is caused by predominantly anaerobic bacteria, which is confirmed with culture. Metronidazole is also used in combination with penicillin in severe spreading infections.

A macrolide, like a clarithromycin, can also be prescribed as a second-line treatment. Due to allergy or drug interactions, clindamycin may be the only alternative for some patients. The clinical outcomes with clindamycin are similar to those with penicillin in treating acute dental abscesses.[24] However, clindamycin treatment is associated with higher gastrointestinal adverse effects rates and increased risk of Clostridium difficile infections.[25] Such risks must be considered when prescribing clindamycin and included in the consent form.(A1)

Analgesics

Nonsteroidal anti-inflammatory drugs (NSAIDs) are more effective in controlling dental pain than opioids and are the first-choice treatment for managing acute dental pain.[26] Combining ibuprofen with paracetamol has also been recommended as they are more efficient together than either drug acting alone.[27] If NSAIDs are contraindicated, paracetamol can be prescribed alone or in combination with oxycodone.[26](A1)

Differential Diagnosis

The differential diagnosis of dental infections is variable and based on presenting symptoms. Localized dental infections can be mistaken for salivary gland pathologies such as sialadenitis, sialolithiasis, and salivary gland tumors. Sialadenitis and sialolithiasis can present with localized facial edema, erythema, and tenderness. A salivary gland tumor can present as a unilateral facial mass. Patients with sinusitis can complain of warm, erythematous skin over the maxillary sinus.

Prognosis

The prognosis for uncomplicated dental infections is good. Dental infections that spread to deeper neck structures carry a worse prognosis and significant mortality rate. Deep neck infections have a mortality rate of 1% to 25%, and mediastinitis can carry a mortality rate of 40%.[28][29]

Complications

Serious complications can arise from dental infections as they spread to potential head and neck fascial planes. There are different paths for the dissemination of the infection. They can spread contiguously to the jaw, causing osteomyelitis. Lower second and third molars infections can migrate to the sublingual, submandibular, and submental spaces, causing Ludwig angina. In children, dental infections may spread to the retropharyngeal or the parapharyngeal space, causing retropharyngeal or parapharyngeal abscesses, respectively. Descending necrotizing mediastinitis is a severe life-threatening infection caused by the descent of dental infection through deep and superficial fascial planes. There have been reports of dental infections spreading and causing cavernous sinus thrombosis.[30] Very rarely, dental infections result in meningitis and subdural empyema.[31] Dental infections and tooth extractions can cause the hematogenous spread of bacteria (bacteremia), which may result in endocarditis, especially in patients with valvular prostheses.[17]