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Antibiotics and Dental Surgery
When and why drugs are necessary

Dear Family Health,
I just heard a news story about a 10-year old girl from the Ukraine who had heart surgery in Canada when she was younger. She was forced to return to Canada for additional heart surgery because her dentist didn’t give her antibiotics for a ‘routine’ dental visit. I myself had a hip replaced last month. My surgeon said my dentist must give me antibiotic pills before I visit the dental office. I have never heard of people needing antibiotics before visiting a dentist. Is this something new? Should my whole family take pills before their appointments?
- Worried in Wetaskiwin

Dear Worried,
You can relax about your family members. For certain people, it is very important to take an antibiotic before dental treatment. However, this is only necessary for a few people with specific medical problems. Antibiotics are mainly used to treat an infection that has already begun. That is, bacteria have collected somewhere in the body and are already causing damage. Antibiotics are taken to help the body fight off the bacteria. For the examples in your letter, the idea is to take an antibiotic to prevent a possible infection. This is called a prophylactic antibiotic. Rather than the antibiotic being taken for many days, a prophylactic antibiotic is usually taken only once, about an hour before an appointment. The antibiotic remains in the body for a few hours to kill bacteria from the mouth that might enter the bloodstream during the dental appointment.

Under specific circumstances, prophylactic antibiotics may be considered.

Cardiac (heart) conditions

Many people have heart murmurs. These extra sounds are made by blood flowing through the chambers and valves of the heart. In addition to the usual ‘lub-dub’ sound of the heart, a doctor will hear other sounds occurring at the same time. Most are of no concern. However, people with these sounds are often sent for extra tests, which may include chest x-rays and an electrocardiogram or ECG. An echocardiograph, another test, takes an ultrasound of the heart. This is the best way to determine the nature of the murmur.

Four valves separate the four chambers of the heart. They ensure blood flows in the right direction through the heart. As we age, these valves (like so many other parts of our bodies) may not work as well as when we were younger. If a valve no longer fully closes, a bit of blood may flow backwards with each heartbeat. In other cases, a valve may no longer open as wide as it once did, so less blood gets through with each beat. In either case, blood may swirl around this area (think of a whirlpool in a fast-moving stream).

If bacteria are in the blood, they may settle on tissues in this area. Eventually bacteria can grow into a mass big enough to interfere with the valve’s normal motion. This very serious medical problem, a bacterial endocarditis, is an inflammation of the innermost layer of the heart's chambers and the valves. Treatment requires weeks of intravenous antibiotics or even open-heart surgery to replace the infected valve.

Most cases of bacterial endocarditis are not the result of medical or dental treatments. However, the American Heart Association (AHA) has published prevention guidelines for doctors and dentists, which have been endorsed by both the Heart & Stroke Foundation of Canada and the Canadian Dental Association. Experts in medicine, dentistry, pharmacology, and microbiology write the guidelines. They were first published in 1955, and are reviewed every five to seven years. The most recent guidelines were published in 1997 and are now being reviewed, with new guidelines expected sometime during 2005.

Years ago, the guidelines sometimes required that combinations of antibiotics be given by injection, intravenous line, or pill. Patients took antibiotics for days before and after a dental appointment. Thankfully, the rules have become simpler over the years. Most needing antibiotics only have to take a few pills one hour before a dental appointment.

The AHA Guidelines specify the various heart conditions that require patients to take antibiotics before dental appointments, including those:

• who have had heart valve replacement surgery (and so are at highest risk of bacterial endocarditis).
• with certain kinds of heart valve problems.
• born with various (congenital) heart problems. These conditions may or may not have required surgery.

Patients who have had coronary (heart) artery bypass surgery do not require antibiotics. Patients seeing the dentist within a few weeks after having ‘stents’ placed in their coronary arteries may be advised to take prophylactic antibiotics. It is only necessary for a short time after the stent procedure.

The guidelines also specify the kinds of dental procedures where at-risk patients will need prophylactic antibiotics. Generally, these are the ones most likely to produce significant bleeding from the gums:

• extractions (tooth removal) and other oral and periodontal (gum) surgeries
• certain kinds of root canal procedures
• dental cleanings (root planing, scaling, and polishing)
• initial placement of orthodontic bands around teeth.

Many common procedures do not require antibiotic protection, including:

• dental radiographs (x-rays)
• local anesthetic injections (freezing)
• many filling procedures
• most root canal treatments
• inserting removable appliances (dentures, retainers)
• impressions
• fluoride treatments
• orthodontic adjustments.

Remember, not everyone at risk of bacterial endocarditis needs to take antibiotics every time they visit the dental office. Dentists and doctors talk with each other to decide who needs antibiotics and for which treatment. The use of antibiotics is kept to a minimum where possible, since patients may risk having an allergic reaction or suffering side effects from an antibiotic. As well, there is worldwide concern that overuse of antibiotics is leading to bacteria becoming resistant to the effect of these drugs. By giving antibiotics to people who do not need them, we are simply adding to the development of antibiotic-resistant super-bugs.

Joint replacements

Joint replacement surgeries (hips, knees) are relatively common. For years, there have been concerns that patients with artificial joints may be at risk of infection from bacteria in the mouth. The process is similar to problems in the heart. Bacteria in the bloodstream may settle around the artificial joint and infect it as blood flows around it. Such infections are difficult to treat with antibiotics, and may require another surgery to replace the artificial joint. The same dental treatments present risks for both heart and joint replacement patients.

There has been much debate over the true risk of oral bacteria infecting these joints. Recently, an expert panel provided recommendations for the proper use of prophylactic antibiotics for artificial joint patients. Ideally all necessary dental treatment should be done before joint replacement surgery, reducing possible risk of infection afterward. For two years following the artificial joint surgery, most patients are advised to take antibiotics before dental treatments that will cause bleeding in the mouth.

Some patients with other medical problems should take antibiotics no matter how long ago they had joint replacement surgery. These conditions include:

• rheumatoid arthritis and systemic lupus (SLE)
• immune (defence) system suppression
• malnourishment
• insulin-dependant (type 1) diabetes
• hemophilia
• a previously infected artificial joint.

No antibiotics are necessary for patients with other orthopedic (bone) surgery implants (such as pins, plates, or screws). Antibiotics and doses recommended by the panel are similar to the AHA Guidelines.

Other conditions that require antibiotics before dental visits

Doctors and dentists may recommend antibiotics for a few other patients before certain kinds of dental treatments. However, the need has not been researched as much as for heart conditions and joint replacements. When antibiotics are suggested, the AHA Guidelines are usually followed. Patients who might require antibiotic prophylaxis include:

• Those having had an organ transplant – These patients must take anti-rejection drugs that weaken their immune system. They may be at risk of serious infections from oral bacteria entering their blood stream. If a patient’s transplant is working well and there are not any complications, the need for antibiotics is much less than for someone who has had a recent transplant or is having complications.
• Those having cancer chemotherapy – Chemotherapy severely weakens the immune system, making it difficult to fight infections. Should dental treatment be needed, antibiotics are often required. Once a patient completes chemotherapy, the immune system recovers. Antibiotics for dental visits are not necessary within a few weeks of chemotherapy ending.
• Those on dialysis (a process used to remove toxic substances from the blood) – These patients are at risk of infection at the sites used to connect veins to the dialysis machine. They may also be at risk of endocarditis even if they do not have the usual cardiac risk conditions.
• Those with weakened immune systems – People with autoimmune disorders (which cause the body to form antibodies and attack itself), on chronic, high doses of steroid medications, or in the later stages of AIDS are included in this group.

As you can see, many conditions may require antibiotic prophylaxis before dental visits. Since they are relatively rare, most people do not require medication. Together, your dentist and doctor can advise you on your need for antibiotics.