Antibiotics are used to fight bacterial infections. They may be taken in pill or liquid form, or used as a mouthwash and then swallowed. Antibiotics are also given by injection.Produced by bacteria, moulds and fungi, antibiotics have the power to destroy or inhibit the multiplication of other types of organisms, especially bacteria. Some antibiotics are effective against fungi and a few viruses as well.

Penicillin, erythromycin, and tetracycline are the most commonly prescribed antibiotics in dentistry. Usually taken for gum infections and abscesses, antibiotics are sometimes prescribed after extractions of infected teeth and during root canal therapy.

If certain medical conditions such as a heart murmur are present, antibiotics are prescribed before any treatment to prevent infection of the heart valves.

Once an antibiotic is ingested, it may be toxic to intestinal bacteria. Desirable (‘friendly’) bacteria as well as undesirable ones will, therefore, be poisoned and destroyed. This leaves the intestinal walls unprotected against irritating or unabsorbed foods, causing inflammation of the tissues.

Similarly, if an antibiotic is taken for a long period of time, the particular strain of bacteria it is meant to destroy may eventually become resistant. As a result, mutant strains of bacteria are produced.

Another side effect to long-term intake of a particular antibiotic is that by destroying bacteria, it produces an imbalance in the micro-organism population. For example Candida, which is a yeast organism, proliferates with long-term antibiotic use because much of the bacterial population is destroyed.

Antibiotics may produce an assortment of gastrointestinal complaints and a variety of allergic reactions that range in seriousness from mild rash to shock and even death. In addition, most antibiotics interfere with the estrogen in birth control pills, rendering the pills inactive. Blood cholesterol levels are raised by some antibiotics, since bacteria that help rid the body of cholesterol are destroyed by the drug.

Since its discovery in 1941, penicillin has been the antibiotic used for the majority of dental infections. The occurrence of side effects depends on how well an individual tolerates the drug. A person allergic to penicillin will usually experience a reaction with half an hour of taking the drug. In some allergic reactions the muscles in the throat become constricted, causing breathing difficulty. In more serious reactions, the capillaries dilate, causing shock which, if not treated immediately, can lead to death.
Other side effects of penicillin use reveal themselves from two hours to three or more days after taking the medication.

These include fever, mental changes, edema (abnormal accumulation of fluid in tissues), abnormal heartbeat, inflammation of the kidneys and renal failure, swollen tongue, many types of skin rashes, and inflammation of any or all parts of the mouth. Because penicillin crosses the placental barrier and is excreted in the mother’s milk, its use should be avoided during pregnancy and lactation.

The antibiotic choice for individuals allergic to penicillin is erythromycin, which was first used in 1952. Although food reduces erythromycin absorption, it may be necessary to take this drug with meals because of its adverse effect on the gastrointestinal tract. Erythromycin is distributed to most body tissues and excreted via the liver in the bile, and in urine and feces.

Side effects associated with erythromycin include gastrointestinal irritation, abdominal cramps, nausea, vomiting, and diarrhea. All the side effects disappear when the drug is discontinued. Individuals taking digoxin, warfarin, or carbamazepine, and those taking theophylline for asthma or bronchitis, may experience adverse reactions to erythromycin and should, therefore, avoid taking it.

Discovered in 1948, tetracylcline is a broad-spectrum antibiotic that affects a wide range of microorganisms. It concentrates in the liver and is excreted into the intestines via the bile. This drug should not be taken by pregnant or lactating women or by children between the ages of two months and eight years because of its side effects.

Tetracycline is secreted in the saliva and the milk of lactating women, and is stored in unerupted teeth of nursing babies. When the teeth erupt they have permanent stains, which darken with age and exposure to light. A decreased growth rate in bones has also been demonstrated in infants and fetuses who have ingested and/or been exposed to tetracycline.
Although tetracycline is prescribed for severe gum disease, it should be taken with caution because of its many side effects. Some of these side effects include lightheadedness, dizziness, and vertigo. People taking this drug should not drive or perform any hazardous jobs. In addition, tetracycline reacts negatively with antacids, iron, oral contraceptives, barbiturates, and warfarin. With long-term ingestion of tetracycline, the targeted organisms may become resistant to the medication. Because the resistant strain of bacteria cannot be destroyed by any antibiotic, the condition is called a “superinfection.”
There are other antibiotics prescribed in dentistry, but like the above-antibiotics, they should be taken with caution and only when absolutely necessary.

Dr. BERTRAND R. STUART, DDS.