CHAPTER 12 Odontogenic Infections
Odontogenic infections are among the most frequently encountered infections afflicting humans, the etiology of which is almost always a carious tooth or a tooth suffering from periodontal disease. The vast majority of these infections are minor and acute, and some even drain through the tooth socket, because they are primarily due to chronic periodontal disease. Consequently, there is considerable interest in periodontitis—a chronic inflammatory disease (and by definition a chronic low-grade infection due to a microbial biofilm) of the tooth-supporting structures—as a potential risk factor in the morbidity and mortality of systemic conditions such as cardiovascular disease, diabetes mellitus, and premature birth. Research is ongoing to delve more deeply into these relationships.1 Refer to the Suggested Readings for more information on periodontal disease. Another topic that frequently arises with reference to odontogenic infection is osteomyelitis, which is an inflammation of the cortical and cancellous bone. It can follow odontogenic infection that is not completely resolved and when appropriate attention is not paid to the jawbone itself on follow-up. Again, refer to the Suggested Readings for more information regarding osteomyelitis.
Odontogenic infections, whether acute or chronic, have been plaguing humanity for millennia, and there are many documented stories, engravings, artifacts, and the like to prove this point.2 A great deal of pain and suffering continues to be a scourge, especially in populations that neglect dental care, do not have access to dental care, or ignore professional advice on proper oral hygiene. Extraction of the offending tooth usually results in resolution of the infection, even without antibiotics. However, some of these minor tooth-related infections occasionally become more serious and potentially life threatening, especially in immunocompromised patients. The need for more aggressive surgical and medical care is usually necessary then to prevent more disastrous results.
Microbiology of Odontogenic Infections
Odontogenic infections are usually caused by normal endogenous flora. The mouth contains many microenvironments, allowing for colonization of many bacterial species. Once this environment is established, which varies with factors such as age, immune status, type of diet, and preferred environment, it can and does change over a lifetime. Table 12-1 lists many of the common “normal” aerobic, facultative, and anaerobic species of bacteria (several fungal species, viruses, and even protozoans can also be found in the “normal oral flora”). In most patients, these normal oral bacteria are the cause of most odontogenic infections. Other organisms can be implicated, however, if there is a compromised host or unusual oral environment, such as that found in chronic osteomyelitis. Facultative streptococci are the most numerous group of organisms in the oral cavity and members of the viridans group are the most abundant; these are classically based on their type of hemolysis on agar. Noticeably absent from these normal organisms are the staphylococci, although they are present in nearly every mouth, but in small numbers. Staphylococcus aureus, in particular, is much more common in the nose and throat, and may participate in mixed odontogenic infections. Gram-negative anaerobes comprise much of the rest of the mouth’s normal flora, and these organisms can increase in numbers, especially in patients with chronic periodontal disease.3
| Aerobic Bacteria | Anaerobic Bacteria |
|---|---|
| Gram-positive Cocci | |
| Streptococcus | |
| Gram-negative Cocci | |
| Neisseria | Veillonella |
| Gram-positive Bacilli | |
| Diphtheroids | |
| Gram-negative Bacilli | |
Adapted from Peterson LJ. Odontogenic infections. In: Cummings CW, ed. Otolaryngology Head and Neck Surgery. Vol 2. 2nd ed. St. Louis: Mosby; 1993:1199.
In a recent study describing the microbiology of head and neck infections of odontogenic origin by Rega and colleagues,4 the most common bacteria isolated were viridans streptococci, Prevotella, staphylococci, and Peptostreptococcus. This finding has been consistent for many years, even as name changes (especially for Bacteroides) have taken place to better reflect more recent genetic information.5–9
Based on the results of many studies in the literature and much clinical anecdotal evidence, two important conclusions can be drawn regarding the microbiology of odontogenic infections: First, almost all odontogenic infections are due to mixed flora. Peterson states that the average number of different organisms is five, but can be as great as 10 or more.10 Second, between one third and two thirds of these infections are primarily anaerobic,4,10 which probably has to do with the timing of obtaining the cultures.
Implications of Microbiology for Antibiotic Therapy
Two microbiologic factors must be kept in mind, however, when making this choice: first, the antibiotic must be effective against Streptococcus, because these bacteria are ubiquitous in odontogenic infections; second, the antibiotic should be effective against a wide range of anaerobes, because up to 90% of infections involve some of these bacteria. Fortunately, oral anaerobes are still very susceptible to available antibiotics.11,12
Regarding recommendations for antibiotics, first, it is most useful to use a bactericidal antibiotic rather than a bacteriostatic, if available. The advantages of a bactericidal antibiotic are (1) less reliance on host resistance, (2) killing of the bacteria by the antibiotic itself, (3) faster results, and (4) greater flexibility with dosage intervals.13 Second, use of the most narrow-spectrum antibiotic first should be considered to allow less opportunity for development of resistant strains. Third, the addition of metronidazole to a beta-lactam antibiotic can add a significant benefit in the treatment of odontogenic infections, especially those considered to be mostly anaerobic. As always, the treating clinician must follow the clinical course of the patient and make the appropriate adjustment in antibiotic therapy as circumstances warrant.14–17
Direction of Spread of Infection
If no treatment is instituted, the infection erodes through the thinnest, nearest cortical plate of bone and into the overlying soft tissues (Fig. 12-1). Fig. 12-1A shows the root apex to be nearest the labial cortex; Fig. 12-1B shows the root apex to be nearest the palatal plate; Fig. 12-1C is a clinical photograph of a patient with a lip swelling, reflecting Fig. 12-1A. Clinical experience reveals that in the maxilla, Fig. 12-1A, is more common in that generally the labial-buccal cortex is thinner. If the root apex is centrally located, the infection erodes through the thinnest bone first, that is, the path of least resistance.
Once the bone has been perforated, local muscle attachments determine the location of the soft tissue abscess (Fig. 12-2). The most common pathway for the abscess is through the labial or buccal bone, occlusal to the muscle attachments, resulting in a vestibular swelling (Fig. 12-3). The vestibular abscess is seen as a fluctuant swelling, literally a “pus pocket,” adjacent to the affected tooth or teeth. If no treatment is provided, this pouch of pus usually ruptures and a sinus tract or fistula is established. At this point, the patient’s pain is relieved and he or she may believe that all is okay, especially because there are few, if any, systemic symptoms. However, if the tooth continues to be neglected, one of several things can happen. Slowly over time the bone involvement with the abscess can increase with more dissolution, possibly involving adjacent teeth. The patient may develop the classic “gum boil” or parulis, which is the body’s attempt at healing the sinus tract with ever-increasing amounts of granulation tissue. Occasionally the tract becomes congested and the pain and swelling may briefly return, until the built-up pressure causes release and relief. This cycle may repeat many times. The one meaningful consequence of continued neglect is development of an osteomyelitis, which may be more severe and more difficult to eradicate. Another unusual possibility is development of an orocutaneous fistula, which is much more common when it occurs in a longstanding mandibular infection (Fig. 12-4).
If the infection perforates the bone above the muscle attachment (see Fig. 12-2, points 2, 4, and 5), fascial space involvement occurs. When this happens, the potential for more severe infection and more significant systemic symptoms becomes greater. A rare occurrence, in my experience, is an odontogenic infection creating a sinusitis, reflected in Fig. 12-2, point 6. The sinus membrane provides a modicum of protection to the spreading infection and allows the body’s defenses to “wall off” the abscess, most commonly.
Fascial Space Involvement
Maxillary Spaces
The canine space becomes infected almost exclusively as a result of apical infection of the root of the maxillary canine tooth. The root must be long enough to ensure that the apex is superior to the insertion of the levator anguli oris muscle. The canine space is located between the anterior surface of the maxilla and the levator labii superioris. When infected, there is usually swelling lateral to the nose and loss of the ipsilateral nasolabial fold. Drainage is most often accomplished with an intraoral stab incision (Fig. 12-5).
Figure 12-5. Patient with a canine space abscess. Note the swelling and obliteration of the nasolabial fold.
(From Goldberg MH, Topazian RG. Odontogenic infections and deep fascial space infections of dental origin, Figure 8-9. In: Topazian RG, Goldberg MH, Hupp JR, eds. Oral and Maxillofacial Infections. 4th ed. Philadelphia: WB Saunders; 2002:169.)
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
