by Trisha O'Hehir
Aspirin was introduced in 1899, and consumers currently consume 80 billion aspirin tablets each year. Aspririn is taken for headaches, arthritis, pain, inflammation, fever, and to prevent heart attacks. The American Heart Association recommends aspirin as a therapeutic agent for heart disease. The old saying, "Take two aspirin and call me in the morning" may still have a ring of truth to it.
In the fifth century, Hippocrates wrote about a bitter powder extracted from the bark of a willow tree with properties to ease aches and pains and reduce fevers. Scientists did a bit of chemical detective work and found salicin to be the agent that reduced pain and fever. The body converts salicin into salicylic acid. In the early 1800s, an Italian chemist was the first to make salicylic acid from salicin. From then on, it was used in high doses to treat pain, swelling, fever, and influenza.
The problem with salicylic acid is that is upsets the stomach and causes intestinal bleeding. In the late 1800s, a German man taking salicylic acid for arthritis had terrible stomach problems. His son, Felix Hoffman, a chemist with Friedrich Bayer & Co., looked for an alternative to counter the side effects of the acid. He put the salicylic acid through a few chemical reactions that blocked the acidic parts with an acetyl group, thus converting it to acetylsalicylic acid (ASA). He found that ASA still relieved pain and fever, but without the stomach upset.
It took a couple of years, but, in 1899, the Bayer Company finished testing this new compound, gave it the name of aspirin, and began marketing it widely.
In the early 1970s, British scientist John Vane and colleagues showed how aspirin works. In 1982 he received the Nobel Prize in Medicine and was made a British knight.
Aspirin works by binding to cyclooxygenase (COX-2) and preventing it from making prostaglandins, the substance that sends the pain message to the brain. In periodontal disease, prostaglandins also register pain, and break down connective tissue and bone.
Aspirin also blocks thromboxanes, which prevent platelet aggregation or blood clotting and may increase bleeding over that same time period. When a person stops taking aspirin, the effects on platelet aggregation continues for the next seven days, as it takes that long for new platelets to form.
Pain isn't a consideration in periodontal disease except for pain on probing. Bleeding is a much bigger concern. As more adults take aspirin daily, the effect of aspirin on bleeding must be considered. Aspirin is now available in two dosages: a children's dose of 81 mg and an adult dose of 325 mg.
In a 2002 study, a single daily dose of 325 mg of aspirin over seven days did not show an increase in bleeding upon probing in periodontally healthy individuals. As a follow-up to that study, researchers at Harvard and Forsyth Dental Schools evaluated the effects of aspirin ingestion over seven days in subjects with gingivitis. After collecting baseline data and including only subjects with bleeding in 20 to 30 percent of sites, all subjects were given placebo pills for seven days to see which subjects were compliant with the protocol. A total of 54 patients were then assigned either placebo pills, 81 mg buffered aspirin, or 325 mg buffered aspirin. They all took one pill each day for seven days. Clinical indices were again measured at the end of the week.
Plaque scores decreased for all groups while bleeding increased significantly for the aspirin groups, and slightly but not significantly for the placebo group. Probing depths for all ranged from 1 mm to 4 mm with an overall average of 2 mm. After one week, those taking aspirin showed an increase in bleeding upon probing and also a decrease in probing depth. The decrease was only 0.2 mm and could be explained by one of two theories. The first is the "Hawthorne Effect," which suggests that participation in the research study inspired subjects to improve their oral hygiene. The second theory suggests that the anti-inflammatory effects of the aspirin led to the decrease in pocket depth, while the anti-thrombolytic effect led to an increase in bleeding.
As you review patients' intake of aspirin, remember that an increase in bleeding may be expected in patients with gingivitis, but not in those who are periodontally healthy prior to taking the drug. Those with gingivitis or periodontitis may exhibit an increase in bleeding upon probing due to their aspirin consumption.
Trisha E. O'Hehir, RDH, BS, is a senior consulting editor of RDH. She is also an international speaker, author, instrument designer, inventor, and oral health detective. Her Web sites are www.perioreports.com and www.toothpastesecret.com. She can be reached at (800) 374-4290 or at [email protected].