As most dentists can attest, the mouth can be a scary place. Despite impassioned assurances from patients, we know that not all flossers are created equal. Lurking in this often-hostile environment are all kinds of nasties including bacteria, fungi and viruses. While some microorganisms in the mouth are described as “good,'' others…. “not so much.” Among these pathogenic villains are certain bacteria that when allowed to thrive wreak all kinds of havoc like bad breath, cavities and bleeding gums.
As young dental students in the early 1980s, we were taught that during invasive dental procedures, dentists, by causing tissues to bleed, were inadvertently introducing harmful oral microbes, namely specific strains of streptococcus, into our patient’s bloodstream. This transient bacteremia, by traveling to and lodging in porous structures such as artificial heart valves and prosthetic joints could theoretically cause infection in certain at-risk individuals.
Around the mid 20th century, the dental profession, feeling a sense of both professional and legal responsibility to protect these patients from potentially life-threatening conditions such as infective endocarditis, adopted generally accepted guidelines regarding antibiotic prophylaxis. Based largely on expert opinion at the time, this seemed like a sensible and prudent measure. Though not a precise science, the list of underlying risk factors requiring antibiotic premedication prior to dental treatment was extensive. But things have changed.
Since the 1950s there has been a progressive reduction in the use of antibiotics for the prevention of infection following dental treatment. Compared to previous guidelines, there are currently only a few medical conditions for which antibiotic prophylaxis is required.
In 2007, The American Heart Association published a revised guideline for the prevention of infective endocarditis, concluding that, “IE prophylaxis for dental procedures is reasonable only for patients with underlying cardiac conditions associated with the highest risk of adverse outcome from IE.” Included are patients with prosthetic heart valves, and those with a previous episode of IE.
Prosthetic Joint Replacements
Likewise, following a careful review in 2014 of the scientific literature, a consensus was reached by a combined panel of dentists and orthopedic surgeons stating that there is no correlation between dental procedures and prosthetic joint infections. Accordingly, current guidelines from both Canadian and American Dental Associations state that in general, routine antibiotic prophylaxis is not indicated for dental patients with total joint replacements.
So why this change?
Despite being largely based on expert opinion, the rationale for antibiotic prophylaxis was never a precise science, containing both ambiguities and inconsistencies. Current recommendations stem from three main principles:
The evidence linking bacteremia associated with dental procedures is largely circumstantial, with no existing controlled studies on the efficacy of antibiotic prophylaxis prior to treatments. The collective published evidence indicates prevention for an exceedingly small number of individuals.
The administration of prophylactic antibiotics is not risk-free and often outweighs the benefit for most patients. Adverse effects such as allergic reactions can be potentially life threatening. Additionally, the widespread use and over prescription of antibiotics promotes the emergence of resistant bacteria, including those likely to cause the very same targeted conditions.
3) Common Sense
Back to dental school in the early ‘80s. Why, wondered this student, would the same concern regarding oral microbes not apply when at-risk individuals caused their gums to bleed during routine daily activities like chewing or brushing? Was flossing a potentially lethal activity? Something seemed intrinsically wrong. The AHA concluded that bacteremia resulting from everyday activities was more likely to cause infective endocarditis than dental procedures. Theoretically, at-risk patients would require lifelong antibiotics which is unwarranted and impractical. Sensibly, increased emphasis should be placed on improved oral hygiene and access to dental care for vulnerable individuals.
Despite a shift in philosophy regarding antibiotic prophylaxis and dentistry, some dentists and medical doctors create confusion for their patients by basing treatment on outdated guidelines. People with underlying cardiac conditions and joint replacements should not hesitate to discuss this subject with clinicians in order to make the best-informed decision. Perhaps encourage them to get back to class!
Dr. Mark Grossman is a practicing dentist and likes to take a bite out of nonsense when it comes to dental issues.