CITATION: Walton RE, Zerr M, Peterson L. 1997. Antibiotics in dentistry--a boon or bane? APUA Newsletter 15(1):1-5.

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Antibiotics in dentistry--a boon or a bane?
Richard E Walton, Marvin Zerr and Larry Peterson
College of Dentistry, University of Iowa, Iowa City, Iowa, USA; College of Dentistry, University of Nebraska, Lincoln, Nebraska, USA; College of Dentistry, The Ohio State University, Columbus, Ohio, USA

The number of prescriptions for antibiotics written by general dentists exceeded 2 per day and by oral surgeons, 10 per day, according to a 1992 report in Medical Advertising News. A recent survey on current endodontic treatment (1) reported that the prescribing of antibiotics is common, particularly for patients experiencing pain or swelling. The proposed use of antibiotics for periodontal disease, if substantiated, will further increase the use of antibiotics in dentistry. However, there is little or no investigative evidence to support the use of antibiotics in many dental applications; the decision to prescribe is empirical. In some circumstances, data from clinical trials even contraindicate their use.

Although the dangers of the misuse of antibiotics, in particular, the emergence of resistance, have been known for decades, recent publicity has brought these concerns into better focus. Newspaper and magazine articles have increased public awareness. Professional articles and editorials (2,3) have substantiated the consequences of misuse of antibiotics and advocated their prudent use in both medicine and dentistry. Whether dentists receive or believe this information and whether they practice the recommendations is debatable. The impression is that antibiotics continue to be prescribed by dentists as much or more as in the past despite the scarcity of clinical trials demonstrating the need for antibiotics. Old habits and beliefs die hard, and there is considerable social and medico-legal pressure on dentists to prescribe antibiotics. Dentists want to make their patients well and to prevent unpleasant complications. These desires, coupled with the belief that many oral problems are infectious, stimulate the prescribing of antibiotics.

It is not that practitioners are prescribing antibiotics arbitrarily and without presumed justification. Textbooks, continuing education lectures, and dental school instructors have likely directed that antibiotics be used (albeit empirically). There is also the impression that patients get better when given antibiotics. The reality is that signs and symptoms are usually cyclical and will often improve spontaneously, then deteriorate later. The temporary improvement is likely in spite of and not because of the prescribed antibiotic.

Antibiotics are prescribed for oral conditions related to endodontic, oral surgical, and periodontal manifestations. The antibiotic prescribed most frequently is penicillin or an analog, especially amoxicillin. (1) Dentists are familiar with penicillin's dosages, low toxicity, and relatively low cost. However, other newer-generation antibiotics are becoming more widely used because of the belief that these more exotic, more expensive drugs are more effective. This belief may be based more on marketing than on fact as their effectiveness has not been demonstrated in clinical trials.

Endodontic Diseases

Endodontic diseases involve the dental pulp and related periradicular tissues. The dental pulp is the viable connective tissue within a tooth. Its major function is to form the tooth around itself. Once this is accomplished, the pulp remains as a vestigial organ and is susceptible to injury from caries, restorations of deep structures, and trauma. Such injuries result in inflammation, sometimes severe pain, and, occasionally, necrosis of the pulp. This necrotic tissue is usually invaded by bacteria. Sequestered within the closed environment of the root canal system, this mixture of necrotic tissue and bacteria cannot be removed by the body, and a root canal treatment or extraction is needed to correct the conditions. Potent irritants (bacterial by-products, remnants of necrotic tissue, inflammatory mediators) diffuse from the pulp into the surrounding bone at the root apex, resulting in inflammation and occasionally the formation of an abscess. This process often does not produce symptoms but at times will result in pain or swelling or both, which can sometimes be severe but is rarely life-threatening.

Whether this pulpal and periapical pathosis is a true infection (an invasion of tissues by pathogenic bacteria) is debatable. Most bacteria recovered from these lesions are common facultative and obligate anaerobic oral bacteria that are relatively nonpathogenic and that have not been shown to proliferate readily in host tissues (Table 1). Rather, they seem able to survive best in necrotic tissue.(4) Therefore the damage they cause may be secondary. Furthermore, there is good evidence that these lesions are actually caused by immune mechanisms reacting to toxins and histolytic enzymes produced by the bacteria (5) as well as to mediators released from the inflamed and necrotic tissue. (6,7)

Even if this condition were indeed an infective process, the effectiveness of antibiotic therapy would be questionable. Because there is no circulation within necrotic pulp or an abscess, it is unlikely that an antibiotic would reach the bacteria in therapeutic concentrations.

Pulpitis. In pulpitis, the tooth pulp is vital but inflamed. Occasionally accompanied by pain, which can sometimes be severe, the inflammation is confined and is not a true infection. Treatment is removal of the inflamed tissue; antibiotics should not be used, although a recent survey (1) indicated that dentists occasionally do so (incorrectly).

Acute apical abscess, localized. These are the most common abscesses in the oral tissues. They begin in the bone at the tooth apex as an inflammatory lesion, which progresses to an abscess. These abscesses may be confined to the bone but often spread to the overlying soft tissues. The resulting swelling is predominantly within the oral cavity but may be seen as a slight elevation of the cheek or lip. The abscess contains mixed bacteria with a predominance of anaerobes. (8) Sundquist et al. (9) and Griffee et al. (10) identified a possible relationship between black-pigmented gram-negative anaerobes (Bacteroides spp.) isolated from the root canals of teeth and symptoms of tenderness, swelling, or exudate.

Emergency treatment consists primarily and most importantly of removing the irritant (bacteria, bacterial by-products, inflammatory mediators) from within the tooth and relieving pressure and releasing purulence by incision and drainage. If the tooth is not salvageable, extraction accomplishes both removal of irritants and drainage. Controlled clinical trials (11,12) have shown that penicillin is of no benefit as a supplement to appropriate local treatment.

Acute apical abscess, cellulitis. An infrequent occurrence, cellulitis is a more severe manifestation of the localized abscess, in which the abscess and the reaction to the abscess disseminates, often rapidly, into other tissues and spaces. The result is noticeable swelling and distortion of facial features. If untreated, this infection can spread to vital structures, resulting in blindness, cerebral abscess, mediastinal involvement, and even death. Such serious sequelae are rare and tend to occur only in otherwise debilitated patients. The role of antibiotics in the management or prevention of these occurrences is unclear. Many patients with facial cellulitis do not demonstrate systemic manifestations. Although they rarely have an elevated temperature or white cell count, it is hoped that administration of antibiotics will control the infection.

Although no clinical trials have demonstrated the efficacy of antibiotics in managing acute apical abscesses that spread into fascial spaces, their use is reasonable. The choice of antibiotic is empirical because no definitive information on the causative pathogenic microorganisms is available. However, it is known that oral infections are usually of mixed bacteria with a predominance of obligate anaerobes.(5,8-10) It has been theorized that this diffuse infection is mediated by streptococci, which elicit factors that facilitate the rapid spread of bacteria and the infection through the tissues. (13) The antibiotic of choice is penicillin, administered orally and with aggressive dosages. Intravenous antibiotics are seldom used except for the patient who is hospitalized with a serious infection.

Local treatment is still most important, that is, removal of the necrotic tissue and bacteria from the pulp space and drainage. Tooth extraction, if indicated, achieves both goals. At best, antibiotics are supplemental; without local treatment, they will not resolve the problem. In fact, serious sequelae have resulted from using antibiotics alone without the underlying problem being corrected.(14)

Microbiological cultures may be of some benefit in a case of cellulitis; however, it is difficult to obtain a good specimen, and culture and identification of the anaerobic flora may take several days to weeks. Therefore, with the need to initiate therapy immediately, antibiotics must be administered empirically. Results of cultures and antibiotic sensitivity testing are helpful if the problem persists. If the source of infection has been identified and removed and drainage achieved, the problem does not usually persist.

Endodontic prophylaxis. Antibiotics are frequently administered to prevent adverse post treatment sequelae of root canal treatment and oral surgery. Controlled prospective clinical trials have demonstrated that antibiotics are of no benefit in treating symptoms after root canal treatment.(15) Adverse reactions (known as flare-ups) occur infrequently.(16)

No studies have been published on the use of antibiotics to prevent infection after endodontic surgery. Clinical trials investigating the effectiveness of prophylactic antibiotics to minimize post treatment infections in other oral surgical procedures have found antibiotics to be of no benefit.(17) Logically, the conclusion would be the same for endodontic surgery.

Periodontal Considerations
The periodontal tissues are the supportive elements of teeth, e.g., the surrounding bone, gingiva, and periodontal ligament. Inflammatory periodontal conditions (Table 1) are common, particularly in adults. Antibiotics have been used in periodontics to manage destructive periodontal diseases, to aid in the management of necrotizing gingivitis and periodontal abscess, and to prevent undesirable sequelae of surgery.

Management of periodontal disease. The use of antibiotics to treat or prevent periodontal disease has received attention in professional publications and in the news media. Based on a recent report (18) of a controlled clinical trial of patients with what might be termed "everyday, garden-variety" chronic periodontitis, newspapers and lay journals have reported that antibiotics may allay disease, without expensive and painful periodontal therapy and surgery. The patients in this study had conditions that would likely require surgery, but some were managed with systemic antibiotics (metronidazole or doxycycline) and locally delivered antimicrobials (metronidazole or chlorhexidine or both).The authors concluded that this "treatment paradigm based on the diagnosis and treatment of anaerobic periodontal infections is likely to be successful in those patients for whom access surgery is recommended."(18) An editorial that carefully reviewed this study (19) cautioned against the interpretation that antibiotics were the major factor in the treatment and control of the disease and that periodontal surgery could be avoided. The editor discussed problems in the design of the study that put in question the validity of the results as applied to the management of the most common forms of adult periodontitis.

Systemic antibiotics do not appear to offer any benefit additional to mechanical therapy in adult patients with periodontitis. (20) More information is required before antibiotic therapy, whether systemic or local, is recommended universally for chronic periodontal disease. Antibiotics, however, have been shown to be a useful adjunct in treating localized juvenile periodontitis, (21) refractory periodontitis, and, possibly, rapidly progressing periodontitis. Local delivery of antibiotics is also of some value in managing specific sites of recurrent disease. Antibiotics, when useful, are at best an adjunctive, not a primary, form of therapy; removal of local irritants is primary.

Treatment of periodontal abscess. Acute abscess of the periodontium manifests as a painful swelling of the gingiva overlying the tooth. The cause is bacteria and bacterial by-products located on the subgingival root surface, which create an injury sufficient to cause liquefactive necrosis. These lesions also have a strong immunologic causative component. Abscesses are usually localized and seldom spread to other tissues.

Treatment consists of local measures (removal of the irritant and drainage) and analgesics. Antibiotics, usually penicillin or tetracycline, are indicated if there are systemic signs, such as elevated temperature. (22) However, periodontal abscesses seldom present with systemic manifestations; therefore, routine management with antibiotics is questionable.

Acute ulcerative necrotizing gingivitis (ANUG). Because necrosis of the tissues surrounding the teeth occurred so commonly in soldiers during World War I, this condition was called "trench mouth." ANUG occurs primarily in patients who are stressed and suffer from lack of sleep, poor nutrition, etc. The condition is associated with fusospirochetal bacteria, although other gram-negative anaerobes, such as Prevotella intermedia, can be present. The marginal gingiva may exhibit a grayish pseudomembrane, which sloughs and bleeds readily. It is often accompanied by malodor and pain.

Treatment is to alleviate the acute symptoms and to eliminate or reduce the local irritants. Patients with local lymphadenopathy and an elevated temperature should receive oral penicillin or, for penicillin-sensitive patients, metronidazole or erythromycin. (22) Again, antibiotics are adjunctive at best; local treatments (removal of irritants and oral hygiene measures) are primary.

Prophylaxis for periodontal surgery. Systemic antibiotics are used by some clinicians routinely to reduce postoperative symptoms and infections. There is no documented benefit to this protocol. In light of clinical trials in which prophylactic antibiotics have been shown to be generally ineffective in other oral surgical procedures, such usage is irrational.

However, newer surgical procedures to enhance regeneration of bone use membranes that are partially exposed to the oral cavity. These membranes wick oral bacteria into tissues. There are indications that systemic antibiotics may enhance regeneration of bone, probably by inhibiting bacteria.

Oral and Maxillofacial Surgery
Antibiotics are prescribed for pericoronitis, facial injuries, surgical prophylaxis, and osteomyelitis. Oral and maxillofacial surgeons often treat patients with many of the conditions above, including endodontic and periodontal infections, on an emergency basis.

Pericoronitis. Pericoronitis is inflammation of a flap (operculum) of gingival tissue that overlies a partially impacted tooth, usually a third molar (wisdom tooth). Food debris and bacteria can invade the space between the tooth and the tissue, which may then become traumatized by occlusion from an upper tooth. This damage results in a secondary infection with pain and swelling, usually on the inside of the mandible extending posteriorly toward the pharynx. Occasionally, the infection is severe with extensive swelling to the face, and the patient is febrile.

Treatment of milder forms of pericoronitis is debridement (irrigation under the flap) or removal of the soft tissue and, often, tooth extraction. More serious infections require more aggressive therapy, including antibiotics. Because the offending microorganisms are from the oral cavity, the antibiotic of choice is penicillin. (23)

Facial injuries. Traumatic injuries to the soft and hard tissues of the face may be treated by an oral or maxillofacial surgeon. These injuries include soft-tissue lacerations, fractured and displaced teeth, and fractures of the facial bones. If the soft-tissue injury is properly debrided and closed carefully, antibiotics are usually not indicated for infection-free healing. (24) However, if the wound is grossly contaminated or cannot be properly debrided, antibiotics may provide some prophylactic benefit.

Antibiotics have been widely used as an adjunct to prevent infection in the management of facial fractures.(25) Recent evidence shows that antibiotics are beneficial when given during treatment but can be discontinued after reduction and fixation of the fractures. Additional antibiotic therapy postoperatively does not decrease the overall rate of infection. (26)

Surgical prophylaxis. Most surgical procedures of the oral tissues have a low risk of infection. Frequently performed in an ambulatory setting, oral surgical procedures are rarely extensive enough to warrant prophylactic antibiotics. Some complicated or extensive procedures, as well as procedures on immunocompromised patients, however, may require the use of prophylactic antibiotics. Procedures that may require prophylactic antibiotics are those that require grafting or complicated surgical manipulation, such as complicated impacted third-molar extractions and extensive dental implant procedures.

When antibiotic prophylaxis is indicated, it should start prior to the operation, the appropriate dosage of the correct antibiotic should be used, and the antibiotics should be discontinued when the surgical procedure has been completed. When these guidelines are followed, the incidence of infection is minimized.(17)

Osteomyelitis. Osteomyelitis is inflammation of the bone marrow. The microcirculation fails in cancellous bone, resulting in ischemia and necrosis of the bone. Because blood-borne defenses cannot access the tissue, bacteria proliferate. The resulting infection can spread and may result in loss of a large portion of the jaw, usually of the mandible. The original incident is usually a jaw fracture or an untreated odontogenic infection. Frequently, patients with osteomyelitis have depressed immune mechanisms. An uncommon disorder, osteomyelitis requires aggressive surgical treatment plus appropriate antibiotic therapy.(27)

Bacteria that are similar to those causing other oral infections have been identified as the cause of osteomyelitis. (28)
Staphylococcus aureus may also cause osteomyelitis in the mandible but to a lesser extent than in other bones of the body.

Treatment usually consists of correcting the original injury and surgically removing necrotic bone. The patient should be hospitalized and administered high doses of intravenous antibiotics. Penicillin is the antibiotic of first choice and clindamycin the second. Microbiological cultures are helpful to identify the microorganisms and to select the appropriate antibiotic. Antibiotics are ordinarily continued for a much longer time than for most other oral infections: for at least 4 weeks after resolution of acute symptoms.

Systemic Prophylaxis
Although the potential exists for oral microorganisms (or their by-products or immunocomplexes) to seed and infect distant tissues after oral procedures, (29) there is no substantiated evidence that this occurs. Consequently, the issue of when and for what conditions systemic prophylactic antibiotics are necessary is controversial. (30) For many reasons, certain cardiac conditions require prophylactic measures (2,31) (Table 2).

Antibiotic prophylaxis to prevent a metastatic infection with oral bacteria in patients with joint prostheses is also controversial. (32,33) Orthopedic surgeons, although recognizing that evidence is lacking, overwhelmingly recommend antibiotic prophylaxis for dental procedures. As yet, the risk:benefit and cost:benefit ratios are unknown. A workshop sponsored by the Council on Dental Therapeutics concluded that the dentist should consult with the patient's orthopedic surgeon and reach a collaborative decision. (34)

Immunosuppressed or bone-marrow-transplant patients may be considered for antibiotic prophylaxis. This recommendation is more empirical than factual; no controlled clinical trials have been done because of the impracticality of such studies. Other immunocompromised patients, such as HIV-positive and AIDS patients, are not at greater risk than healthy patients and do not require antibiotic prophylaxis for routine dental treatment. (2)

The Role of the Physician
Patients with oral conditions or facial injuries that involve the oral cavity may occasionally be seen by physicians. Often these conditions involve pain or swelling or both, and the physician may be tempted to prescribe antibiotics. Clearly, the majority of these patients do not benefit from antibiotics. The physician should instead refer the patient to a dentist for appropriate treatment.

Treatment and prophylaxis with antibiotics are normal parts of oral care. However, the indications for antibiotics in dentistry are limited. These indications include serious odontogenic infections with rapid spreading, diffuse swelling, and systemic signs. Management of some periodontal conditions is another indication, although the best antibiotic and the exact conditions warranting their application have not yet been clearly defined.

Some infections of the jaws, including osteomyelitis and severe pericoronitis, may also be treated aggressively with the adjunctive use of antibiotics. Placement of regenerative membranes may benefit from antibiotic prophylaxis.

Prophylaxis with antibiotics to prevent bacteremia and metastatic infection is indicated in some situations. However, this application is controversial because of the lack of controlled, albeit difficult to perform, clinical trials.

It is apparent that antibiotics are used widely in dentistry, often unnecessarily. Dental practitioners must become better educated about the prudent use of antibiotics and the dangers and cost of their overuse and misuse.


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