antibioticsBased on the wide variety of prescription antibiotics that have been given to patients presenting to my office for evaluation and possible treatment, there seems to be a significant misunderstanding and controversy around the topic. The confusion stems from being able to determine when a prescription is needed and what to prescribe; if a prescription is necessary, the dosage, frequency and duration can also cause some confusion.

I'd like to eliminate some of this misperception about the use of antibiotics for patients with disease of endodontic origin, and suggest that most of the antibiotic prescriptions dispensed for tooth pain are unnecessary, and in fact, inappropriate.

Not all diagnoses warrant antibiotic therapy
Before prescribing any drug, an appropriate diagnosis must be made. If the diagnosis warrants the need for antibiotics, then the most appropriate medications may be assessed. According the Center for Disease Control and Prevention (CDC), nearly half of all antibiotic prescriptions are improperly dispensed. This certainly seems to be the case in dentistry since antibiotics are routinely prescribed for patients in pain – especially pain suspected to be of endodontic origin. Pain by itself, however, is an inappropriate symptom to treat using antibiotics as no reputable clinician would prescribe antibiotics to treat back pain. When a dental patient in pain is determined to have an irreversible pulpitis from deep caries and implying a vital pulp, the appropriate treatment is endodontic therapy or extraction along with pain medication.

If a patient presents with pain of odontogenic origin and the diagnosis is necrotic pulp, the pulp may or may not be infected. In either case, the appropriate treatment is once again, endodontic therapy or extraction. In other words, the source of infection or potential infection should first be removed. If the patient is swollen, has swollen nodes and an elevated body temperature, this may suggest systemic involvement and the presence of an infection too severe for their natural immune system to handle. Only in these rare circumstances would antibiotic therapy be indicated.

Again, let me say that antibiotics are rarely required in outpatient dental treatment and their overuse is causing more harm than good. According to the CDC, antibiotic resistance is so common that it has been a concern for years and is considered one of the world's most critical public health threats.

Know your antibiotics
If antibiotic therapy is indicated, selecting an antibiotic with the narrowest spectrum that includes the most likely pathogens would be the most efficacious route and result in the fewest side effects – which include antibiotic resistance of organisms without dental implications, nausea, diarrhea and dyspepsia. For patients requiring antibiotics secondary to an infection of endodontic origin, the antibiotic of choice is still penicillin V. Although amoxicillin is by far the most frequently prescribed antibiotic based on my experience, it has a broader spectrum than necessary that can lead to unnecessary side effects. Its advantages over penicillin are its increased bioavailability requiring less frequent dosing. Therefore if it is used, it should be prescribed three times a day.

Cephalosporins can be used but they don't offer any advantage over penicillin V unless the patient is hospitalized. Cephalosporins are effective against S aureus, an organism responsible for many secondary infections acquired in hospitals. For penicillin-allergic patients, the antibiotic of choice is clindamycin. Macrolides, such as erythromycin and azithromycin, have no place in the treatment of odontogenic infections and have the potential to cause significant harm. Tetracyclines, although effective for the treatment of some periodontal infections, are not indicated in the treatment of patients with infections of odontogenic origin.

If the source of the infection has been removed and the patient fails to respond favorably after two to three days of penicillin V or clindamycin therapy, it is necessary to add metronidazole. Metronidazole is highly effective against anaerobic bacteria but inactive against obligate aerobes. Therefore, it is not appropriate as a first line of defense or replacement antibiotic for infections of odontogenic origin, but is very effective in combination with the primary antibiotic of choice.

The recommended antibiotic dosages are as follows:

  • Penicillin V: 500mg QID (Four doses in one day)

  • Amoxicillin: 500mg TID (Three doses in one day)

  • Clindamycin: 300mg TID or QID

  • Metronidazole: 500mg TID or QID

Finally, there are no precise recommendations for the duration of antibiotic coverage. Most dental infections resolve after five to seven days and if the patient's signs and symptoms have been resolved, there is no beneficial outcome to extending antibiotic therapy for a longer period.

Glen E. Doyon, DMD, Spear Contributing Author [ ]


Commenter's Profile Image Brent Hehn
May 22nd, 2014
Excellent summary and very practical, I seem to be seeing more and more penicillin allergies, and am hesitant in giving more elderly patients clindamycin due to more severe side effects, are there any other options besides clindamycin in penicillin allergic patients?
Commenter's Profile Image Glen Doyon
May 23rd, 2014
Possible allergic reactions are, of course, an important reason to prescribe antibiotics only when appropriate. A lot of patients report penicillin allergies. Quite frankly, most have never had an allergic reaction. You need to ask. If they report nausea or diarrhea, that's NOT an allergic reaction. Just try to use the appropriate formulation of penicillin. They vary. If they report that they got a rash, that's NOT an IgE mediated reaction and you can very very likely use a cephalosporin. If they report hives or an anaphylactic reaction, the use clindamycin. To my knowledge, the only side effects to which you may refer wight he use of clindamycin would be gastrointestinal, and those same side effects, including pseudomembranous colitis associated with C difficile, occur with other antibiotics such as amoxicillin and Augmentin. Ask your patients if they have taken antibiotics before and if they are prone to having diarrhea when they have. Incidence of antibiotic related diarrhea in dentistry range from 2-10% and most of it is nuisance diarrhea. Factors that may contribute to increase potential for diarrhea associated complications include exposure to C difficile (you have to have the care workers or recent hospital stays by the patient) and older age, poor immune response and the use of acid reduction drugs. For the most part, you are safe in using clindamycin for the short duration required for almost all odontogenic infections.