Antibiotics do not prevent recurrent myocardial infarcts in subjects with periodontitis

Periodontitis, an infection of the gingiva and tooth-supporting tissues, may influence the effectiveness of antibiotics used for the prevention of recurrent cardiovascular events. A three-month course of treatment with antibiotics decreased recurrence of cardiovascular events in patients without periodontitis, while the medication was found to have no effect in patients with periodontitis. This is the first time dental infections have been linked to the effectiveness of long-term treatment with antibiotics designed to prevent myocardial infarcts.

This information was the result of research partially funded by the Academy of Finland and conducted at the Institute of Dentistry, University of Helsinki, and at the Divisions of Cardiology and Infectious Diseases in the Hospital District of Helsinki and Uusimaa. The results of the research are published in the journal Atherosclerosis in January.

According to the results, long-term antibiotic medication would prevent myocardial infarcts in patients that do not have periodontitis, or related signs of inflammation such as disease-causing bacteria or antibodies to those bacteria. Periodontitis appears to be such a significant chronic infection that the effect of antibiotic treatment in preventing cardiovascular events is lost in patients that suffer from it. During one year of observation, patients with no signs of periodontitis were more likely to avoid new cardiovascular events. A total of 79% survived without a new cardiovascular event compared with 74% of patients without teeth and 66% of those with periodontitis.

The differences in patients under the age of 65 were even more noticeable: 90% of non-periodontitis subjects completed the year without a new cardiovascular event, compared with only 64% of those with periodontitis and 50% of those without teeth. In patients under the age of 65, periodontitis may cause a fivefold increase in the risk of recurrent, acute cardiovascular events in comparison with healthy people.

The research material examined 141 patients that were hospitalised for acute cardiovascular events (myocardial infarct or unstable angina pectoris). The double-blind trial involved registering the recurrence of new cardiovascular events over one year of observation following the administration of a three-month course of clarithromycin/placebo. X-rays were used to evaluate the status of teeth and tooth-supporting tissues. The presence of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, the two most important periodontal pathogens, was studied in the saliva, and the serum antibodies for these bacteria were measured using a method developed and used only at the Institute of Dentistry, University of Helsinki.

Periodontitis is an infection of the gingiva and tooth-supporting tissues that destroys the tissue fibres and alveolar bone that supports the teeth, and may eventually lead to loss of teeth. According to the Health 2000 study, up to 64% of the Finnish adult population has deepened periodontal pockets related to periodontitis and about 20% have a severe form of the disease.