ANTIBIOTICS are among the principal drugs used by dentists. Once it 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 tissue inflammation. Similarly, if an antibiotic is taken for a long period of time, the strain of bacteria it is meant to destroy may eventually become resistant. As a result, mutant bacterial strains are produced. Another side effect of long-term antibiotic use is that it disrupts the microbial population by destroying bacteria. For example, Candida, a yeast organism, proliferates during long-term antibiotic use because much of the bacterial population is destroyed.
In dentistry, chemotherapy mainly uses antibiotics to treat 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 can destroy or inhibit the growth of other organisms, especially bacteria. Some antibiotics are effective against fungi and a few viruses as well. Penicillin, erythromycin and tetracycline are the most prescribed antibiotics in dentistry.
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 oestrogen in birth control pills, rendering the pills inactive. Blood cholesterol levels are raised by some antibiotics because the drugs destroy bacteria that help rid the body of cholesterol. Since its discovery in 1941, penicillin has been the antibiotic used for most dental infections. The occurrence of side effects depends on an individual’s tolerance to the drug. A person allergic to penicillin will usually experience a reaction within 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, oedema (abnormal accumulation of fluid in tissues), abnormal heartbeat, inflammation of the kidneys and renal failure, swollen tongue, various 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 faeces. Side effects associated with erythromycin include gastrointestinal irritation, abdominal cramps, nausea, vomiting and diarrhoea. 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, tetracycline 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 foetuses 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 light-headedness, 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 tetracycline use, the targeted organisms may become resistant to the medication. Because the resistant bacterial strain 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 necessary.