Both studies are presented this week at the American Heart Association's (AHA's) Scientific Sessions 2011, which are running from 12-16 November, in Orlando, Florida. Abstracts of their reports are available to view online in the AHA journal Circulation.
In their nationwide, population-based study, Drs Emily (Zu-Yin) Chen and Hsin-Bang Leu from the Cardiology department at Taipei Veterans General Hospital, examined data on over 51,000 adults who had received at least one full or partial tooth scaling from a dentist or dental hygienist, and a similar number of matched controls who had never had their teeth professionally cleaned.
None of the participants had a history of stroke or heart attack. The data came from Taiwan National Health insurance records, and the researchers ran statistical tests to compare the cardiovascular event rates between the two groups for an average follow- up of seven years.
They found that participants who had their teeth professionally scaled frequently or occasionally had a 24% lower risk of heart attack and a 13% lower risk of stroke compared to those who did not. The researchers considered tooth scaling frequent if it occurred at least twice or more in two years, and considered it occasional if it happened once or less in two years.
Chen, a cardiology fellow at Taipei Veterans General Hospital, told the press:
"Protection from heart disease and stroke was more pronounced in participants who got tooth scaling at least once a year."
She suggested that professional tooth scaling removes inflammation-causing bacteria that in turn can lead to heart disease and stroke.
One drawback of the study is that the researchers did not adjust the results to take into account other potential risk factors for cardiovascular disease, such as weight, smoking and race, since this information wasn't in the health records.
The Swedish study was the work of Dr Anders Holmlund of the Centre for Research and Development of the County Council of Gävleborg, and senior consultant, Specialized Dentistry, and Dr Lars from the Department of Acute Medicine at Uppsala Academic Hospital.
They examined data on 7,999 participants with periodontal or gum disease and found that types of gum disease predict risk for heart attack, congestive heart failure and stroke in different ways and to different degrees.
Afer adjusting for age, gender, smoking and education level, their results showed that:
- Participants who had fewer than 21 teeth had a 69% higher risk of heart attack compared to those who had the most teeth.
- Participants with most infection (ie the highest number of deepended periodontal pockets around the base of the teeth) had a 53% higher risk of heart attack compared to those with the least infection (fewest number of pockets).
- The participants with the fewest number of teeth had 2.5 times the risk of congestive heart failure compared to those with the most teeth.
- Those with the highest incidence of gum bleeding had 2.1 times the risk of stroke compared to participants with the lowest incidence.
"Markers of periodontal disease predict future common cardiovascular events in different ways, suggesting that they are risk indicators for different cardiovascular disorders."