Principles of Management and Prevention of Odontogenic Infections

Complete History

The goal of history-taking is to gather as much pertinent information as possible and to guide the clinician in as accurate and efficient a manner as possible. Components of history-taking and their significance are summarized in Table 16.3 .

The first step in history-taking is to thoroughly elicit the patient's chief complaint. Although it is important to document the chief complaint in the patient's own words, vague complaints such as “my tooth hurts,” “my jaw hurts,” and “my face is swollen” must be probed further to include details such as the location, severity, duration, and quality of the pain and/or swelling. Certain symptoms are associated with severe infections with involvement of deeper spaces; this should raise immediate concerns and lower the threshold for prompt, if not immediate, expert consultation or activation of the emergency medical system. These include fever and malaise, difficulty breathing (dyspnea), difficulty or pain on swallowing (dysphagia or odynophagia), change in voice (dysphonia), and limited mouth opening (trismus).

The next step is to obtain a thorough history of the chief complaint (history of present illness). This provides the clinician with valuable clues that could help determine the origin and etiology of the infection, any involved anatomic spaces, and the aggressiveness of the infection.

Common questions include:

• “Did you have any pain or other symptoms before this occurred?”

• “Did you have any dental treatment or injuries before these symptoms appeared?”

• “For how long have you had these symptoms?”

• “Did the pain change in character, intensity, or location?”

• “Have you sought any care for this problem? If so, what treatment?”

Knowledge of the initial symptoms gives the clinician clues as to the origin of the infection. For example, if the patient had a history of chronic dental pain in the area of the chief complaint, necrosis or severe periodontal disease of this tooth could be the suspected cause. This will allow the clinician to focus on this area during the comprehensive physical examination. Changes in the character and location of pain could indicate progression of the infection. For example, if pain from a mandibular molar changed to pain in the jaw and the neck, the clinician should have a high suspicion of spread to a deeper space(s). Duration of the symptoms could help the clinician determine the aggressiveness of the infection. In general, symptoms that have been steady and persistent for an extended period of time (>30 days) indicate a chronic infection that is being contained by the host defense system. On the other hand, acute-onset symptoms with rapid exacerbation generally indicate a more aggressive infection, compromise of the host defense system, or both. Previous treatment history also provides the clinician with important clues regarding the aggressiveness of the infection. If a patient presents with an infection despite having had the cause of the infection removed and/or drainage of the infection, this could indicate an aggressive infection requiring the need for more aggressive management.

After meticulously obtaining information about the symptoms and history, a thorough past medical history and social history are elicited in the usual fashion. When using a questionnaire-based form for a health history, it is essential for the practitioner not only to review the patient's responses, but to further discuss the responses with the patient and/or caregiver to avoid missing important items or miscommunication. If the patient is a poor historian, it is often necessary to contact the patient's primary care provider or specialist to obtain a complete medical history via medical consultation.

The next step is a thorough review of systems. This is the step in the history-taking when further symptoms are elicited, including not only those of the oral cavity and head and neck, but those of the entire body (such as constitutional symptoms, chest pain, shortness of breath, polyuria, polydipsia, and polyphagia). This step is crucial in identifying pertinent positive and negative symptoms that could help either rule in or rule out severe infections. It is also crucial in finding potential medical problems (comorbidities) that could impact the healing and resolution of the infection, not elicited in the medical history (such as undiagnosed diabetes mellitus or a human immunodeficiency virus [HIV] infection or other immunocompromised state).

Physical Examination

Physical examination must be performed in a comprehensive and organized fashion, and the clinician should avoid examining the oral cavity first, which makes it easy to miss obvious yet extremely important findings that have a direct impact upon management. It is recommended that the clinician begin from “big to small,” or “outside then inside.” This begins with obtaining vital signs (temperature, blood pressure, heart rate, and respiratory rate). Patients with odontogenic infections often have an elevated heart rate of more than 100 beats/min (tachycardia), a respiratory rate of more than 20 breaths/min (tachypnea), and increased blood pressure (hypertension). Although pain and anxiety can elevate these vital signs, such findings should raise concerns for the practitioner. An elevated temperature to 101°F (38.3°C) or higher strongly indicates bacteremia and systemic involvement and invariably requires immediate intervention, typically by an oral and maxillofacial surgeon. In addition to vital signs, oxygen saturation (SpO ₂ ) should be determined with pulse oximetry to ensure adequate tissue oxygenation. Decreased oxygen saturations below 95% in an otherwise healthy patient should raise concerns for the possibility of airway compromise or obstruction.

After obtaining vital signs, the patient should be examined for general appearance. This could occur as early as the moment the patient enters the examination room. If the patient does not appear distressed and is ambulating and speaking without difficulty, the likelihood of a severe infection is not very likely. On the other hand, if the patient appears fatigued and lethargic ( Fig. 16.6 ), has an increased work of breathing, has a change in their voice pattern, and is unable to handle secretions (drooling), it is highly likely that a severe infection is present. The clinician should also listen for any signs of high-pitched breath sounds (stridor), which could indicate obstruction of some part of the airway.

Next, a focused head and neck examination should be performed, beginning with inspection. The clinician should carefully look for any swelling or asymmetry, as well as erythema (redness) of the head and neck region. If any of these findings is present, it could indicate involvement of the surrounding space(s), especially if it corresponds to the area of the patient's symptoms. Common areas of head and neck swelling include the temporal, orbital, nasolabial, cheek, and mandibular angle regions and along the inferior border of the mandible ( Table 16.4 ). Any areas of swelling must be examined with gentle palpation and characterized accordingly. The consistency may be soft and normal, doughy, firm and hard (indurated), or fluctuant. A doughy consistency is commonly seen in the inoculation (edema) stage of the infection. At this stage, tenderness is generally mild and diffuse. Induration is usually a hallmark of cellulitis and is diffuse and exquisitely tender to palpation. Fluctuance indicates a fluid (e.g., purulence) collection, which is characteristic of the abscess stage. At this stage, the infection is better localized than the cellulitis stage and less tender due to less tissue pressure. It must be noted that an odontogenic infection is an ongoing spectrum of stages; therefore all of these various consistencies could overlap and be present at the same time.

Mandibular mouth opening should be assessed; this is of particular importance for three main reasons. The first is that limited mouth opening (trismus) may indicate involvement of deep spaces, in particular the masticator spaces (spaces involving the muscles of mastication), which require prompt aggressive treatment by an oral and maxillofacial surgeon to prevent progression to deeper spaces and airway compromise. The degree of trismus generally corresponds to the severity of the infection. It must also be noted that swelling is not a prominent finding in such infections (in fact, it may not be present at all), which further highlights the significance of trismus. The second reason that mouth opening is important is for intraoral access. Limited mandibular opening precludes a thorough intraoral examination or intraoral surgical intervention. Therefore patients with severe trismus secondary to an odontogenic infection often require surgical drainage and elimination of the infection source under general anesthesia in a hospital setting. The third reason trismus is important is that when a patient with limited mouth opening undergoes general anesthesia, special considerations and measures must be made to protect the airway with an endotracheal tube, usually via endoscopically guided fiberoptic nasal intubation techniques. It must be noted that although trismus may be due to guarding (self-protection) secondary to pain or anxiety, the clinician should nevertheless have a heightened sense of awareness when encountering trismus. Using a maximum interincisal opening of 40 mm as the norm, the clinician can measure the distance between the maxillary and mandibular incisors without assistance (active) and with gentle assistance (passive). Ideally a ruler should be used to measure the interincisal distance; however, the use of fingerbreadths (three fingerbreadths generally corresponds to 40 mm) is a common and acceptable method. A limited mouth opening may indicate involvement of the masticator spaces, and trismus of less than 15 mm usually indicates the presence of a severe infection.

After examining the head and neck, attention is directed to the oral cavity. This examination should also be performed in a systematic fashion, progressing from general to specific areas. The clinician should avoid the temptation of examining the swelling or dentition first. Areas such as the pharyngeal walls, uvula, and the floor of mouth must be examined. Infections extending to such areas could compromise the airway, and abnormalities must be recorded and further investigated. Then, the hard and soft palate, the facial vestibule, and the gingiva should be carefully inspected, palpated, and characterized. Next, the dentition should be examined for caries, periodontal disease, large restorations, any defects around existing restorations, tooth fractures, mobility, percussion sensitivity, and vitality (for involved teeth only). When a severely carious or periodontally involved tooth is in the immediate vicinity of an intraoral swelling, it can oftentimes be deemed the source of the infection. However, when multiple problematic teeth are present or the physical examination is equivocal, ancillary testing such as vitality testing and radiographic examination is warranted.

Imaging Studies

In a general dental or oral and maxillofacial surgery office, common imaging studies used for odontogenic infections include periapical radiographs, panoramic radiographs, and cone-beam computed tomography. Bitewing radiographs, which are frequently obtained for routine caries surveillance and restorative purposes, have no significant role in the assessment of odontogenic infections because they do not capture the periapical region, which is the most common and important area from which odontogenic infections originate. Panoramic radiographs allow a general overall view of the jaws, nasal cavity, maxillary sinuses, and dentition, and have the benefit of simple acquisition with minimal discomfort for the patient (especially if trismus is present). Periapical views allow a more detailed assessment of the teeth and their periapical regions and have the benefit of less radiation dosage. A cone-beam computed tomography scan allows a three-dimensional view of the maxillofacial skeleton and teeth and is useful if the source of the infection is unclear based upon the history and clinical examination (e.g., multiple adjacent carious teeth, suspected jaw fracture, or osteomyelitis). The clinician must weigh the risks and benefits of each imaging modality and provide the most comprehensive assessment with the least morbidity to the patient (ALARA rule: as low as reasonably achievable). Adjunctive techniques could be used such as insertion of a radiopaque material (such as gutta percha) through an existing parulis, fistula, sinus tract, or periodontal pocket to localize the precise source of the infection. This technique is useful when multiple defective teeth are adjacent to an area of infection. Deep fascial space infections that either pose a risk for airway compromise (such as the lateral pharyngeal space or retropharyngeal space) or are not easily identified on physical examination (such as the infratemporal space) may benefit from obtaining medical-grade computed tomography imaging in a hospital setting. It must be emphasized that radiographic examination can never substitute for a thorough history and physical examination.

Laboratory Studies

Laboratory testing may be used to assist in the patient evaluation. However, for odontogenic infections, these are invariably limited to use in a hospital setting. The main purpose of this ancillary testing is to assess the host's systemic response to the infection, via bacteremia, as well as to monitor recovery following any treatment provided. Since localized infections (e.g., vestibular abscesses) generally do not result in significant constitutional symptoms, laboratory tests are rarely, if ever, required. However, deeper space infections, such as infratemporal lateral pharyngeal and retropharyngeal space abscesses are difficult to examine clinically and are typically associated with significant constitutional symptoms such as fever and malaise. In such infections, laboratory studies also serve as adjuncts to the physical examination when assessing response to treatment.

The most commonly used laboratory study is the complete blood count, with focus on the white blood cell (WBC) count, and more specifically, the WBC differential count. The rationale for this test is that an elevated WBC represents a strong immune response to the infection in the form of increased WBC production and mobilization into the bloodstream. It is important to understand that in an acute setting, the WBC count may be affected by noninfectious factors such as medications (e.g., corticosteroids) and stress and should always be correlated within the overall clinical context. A differential WBC count can help mitigate the effects of such factors by focusing on the immature granulocytes (polymorphonuclear leukocytes and neutrophil band cells, or a “left shift” in the differential WBC count), which serve as better indicators of an infectious process; an increase in these immature cells indicates that the bone marrow is increasing production of these cells in order to combat a systemic infection. Following resolution of the bacteremia and infection, the WBC count will gradually return to baseline; this can be a useful study to monitor progression of the infection.

Similar to any other ancillary testing, laboratory studies are intended to complement the history and physical examination and, more importantly, affect management of the patient. Indiscriminate radiologic or laboratory testing cannot be justified if it is not expected to impact upon the overall management of the patient.

Overall Assessment

Once a thorough patient history is obtained and a comprehensive physical examination is performed followed by any indicated ancillary testing, the clinician should be able to determine the location and stage of the infection as well as the etiology and severity of the infection. As discussed previously, the majority of the assessment could be determined based upon a thorough history and physical examination, and any necessary ancillary tests such as imaging and laboratory studies may help the clinician formulate an accurate diagnosis. The location of the infection may be confirmed based on an accurate physical examination as well as imaging studies, when necessary. The specific stage of the infection (inoculation, cellulitis, abscess, resolution stages) is based largely on the history as well as clinical presentation. In general, cellulitis, which appears in the initial stages of infection, indicates greater severity with uncertain progression, whereas an abscess indicates that the host defense system has effectively localized the infection via containment. The etiology of the infection is determined by integrating the history, physical examination, and imaging studies. It is important to note that the clinician should always consider nonodontogenic etiologies (e.g., tumor) in the differential diagnosis and not assume that all swellings or pain around the head, neck, and oral region are odontogenic in nature.

Medical Comorbidities

Two main categories of medical comorbidities that adversely affect the host defense system are inadequately controlled metabolic diseases and conditions that directly affect the immune system.

Poorly controlled diabetes mellitus is strongly associated with impaired healing. Hyperglycemia causes decreased leukocyte chemotaxis and phagocytosis and severely impairs one's ability to resist and combat infections. Patients with severe infections, especially in a hospital setting, require careful control of blood glucose levels in order to optimize the host defense system after appropriate surgical management. Severe alcoholism, which is frequently accompanied by malnutrition, also severely impairs the body's ability to defend against infections.

Hematologic cancers such as leukemia and lymphoma adversely affect the function of leukocytes and therefore the ability to defend against infections. In addition, in severe HIV infections, both the B and T lymphocytes are affected, making the patient particularly susceptible to infections and a poor response to treatment. However, HIV seropositivity alone does not indicate a lack of ability to defend against odontogenic infections, because odontogenic infections are caused mostly by extracellular pathogens, not intracellular pathogens, against which T lymphocytes are primarily responsible to combat.

Certain medications depress the immune system and increase the risk of odontogenic infections and poor treatment response despite appropriate management. Chemotherapeutic agents for malignant conditions commonly cause bone marrow depression, thereby weakening the immune system. In some chemotherapeutic agents, these effects can last for up to 1 year or more. Immunosuppressants and corticosteroids used for various indications (such as autoimmune diseases and organ transplantation) impair the function of lymphocytes and decrease immunoglobulin production.