News Author: Sue HughesCME Author: Charles P. Vega, MD

June 7, 2010 — Individuals who do not brush their teeth twice a day have an increased risk of heart disease, a new study shows

The study was published online May 27, 2010 in BMJ; corresponding author is Prof Richard Watt (University College London, UK).

The researchers note that while it has been established that inflammation in the body (including mouth and gums) plays an important role in the buildup of atherosclerosis, this is the first study to investigate whether the number of times individuals brush their teeth has any bearing on the risk of developing heart disease.
They analyzed data from more than 11 000 adults who took part in the Scottish Health Survey, in which individuals were asked about lifestyle behaviors such as smoking, physical activity, and oral health routines. Questions asked included how often they visited the dentist and how often they brushed their teeth (twice a day, once a day, or less than once a day). Information was also collated on medical history and family history of heart disease and blood pressure. Blood samples were taken from a subgroup of participants and tested for C-reactive protein (CRP) and fibrinogen levels. The data gathered from the interviews were linked to hospital admissions and deaths.
Results showed generally good oral hygiene practices, with 62% of participants saying they visited the dentist every six months and 71% reporting that they brushed their teeth twice a day. After adjustment for established risk factors, it was found that participants who reported less frequent toothbrushing had an increased risk of heart disease compared with people who brushed their teeth twice a day. Participants who had poor oral hygiene also had increased levels of CRP and fibrinogen.
Hazard Ratio for Cardiovascular Events (Fatal and Nonfatal) Relative to How Often Teeth Are Brushed Each Day

Frequency of toothbrushing vs HR* (95% CI)
Twice a day vs 1.0
Once a day vs 1.3 (1.0–1.5)
Less than once a day vs 1.7 (1.3–2.3)
p for trend vs 0.001

*Adjusted for age, sex, socioeconomic group, smoking, physical activity, visits to dentist, body-mass index, family history of cardiovascular disease, hypertension, and diabetes

The researchers say: "To the best of our knowledge, this is the first study to show an association between a single-item self-reported measure of toothbrushing and incident cardiovascular disease in a large representative sample of adults without overt cardiovascular disease."
They add: "Our study suggests a possible role of poor oral hygiene in the risk of cardiovascular disease via systemic inflammation. Raised inflammatory and homoeostatic responses as well as lipid metabolism disturbance caused by periodontal infection might be possible pathways underlying the observed association between periodontal disease and the increased risk for cardiovascular disease."
But they note that further studies are needed to confirm whether the observed association between oral health behavior and cardiovascular disease is in fact causal or merely a risk marker.

References
1. de Oliveira C, Watt R, and Hamer M. Toothbrushing, inflammation, and risk of cardiovascular disease: Results from Scottish Health Survey. BMJ 2010; DOI:10.1136/bmj.c2451. Available at: http://www.bmj.com/.

Additional Information
Information about oral hygiene and cardiovascular risk is available online on the National Institute of Dental and Craniofacial Research Web site

Clinical Context
Systemic inflammation plays a role in cardiovascular events, and a previous study by Danesh and colleagues, which was published in the July 22, 2000, issue of the BMJ, found that certain serum markers of inflammation were independent predictors of the risk for coronary heart disease events. Specifically, CRP and serum amyloid A protein were significantly associated with the risk for nonfatal myocardial infarction or coronary heart disease death, even after a multivariate analysis. The serum white blood cell count and albumin levels were not significantly associated with coronary heart disease risk. Periodontal disease is associated with a moderate systemic inflammatory response. The current study explores the relationship between oral hygiene behavior and inflammatory response as well as the risk for cardiovascular disease.

Study Highlights

• Data were drawn from the Scottish Health Survey administered in 1995, 1998, and 2003. The survey is a broad questionnaire of health behaviors and outcomes among adults 35 years and older.


• Participants who were edentulous (no natural teeth) or had existing cardiovascular disease were excluded from the current analysis.


• Researchers of the current study specifically examined oral hygiene behaviors and their relationship to a composite of cardiovascular diagnoses, which were derived from hospital discharge and death certificate databases. These diagnoses included myocardial infarction, coronary artery bypass surgery, percutaneous coronary angioplasty, stroke, and heart failure.


• The main study outcome was adjusted to account for other cardiovascular risk factors.
  Researchers also examined the relationship between oral hygiene and 2 serum markers of systemic inflammation: CRP and fibrinogen.


• 11,869 individuals provided study data. The mean age was 50 years old, and 46.1% of participants were men.


• 62% of participants reported visiting a dentist at least every 6 months, and 71% said they brushed their teeth twice a day.


• Participants who brushed their teeth less than twice a day were more likely to be older and have a higher number of cardiovascular risk factors.


• There were 555 cardiovascular events during an average of 8.1 years of follow-up.


• Compared with participants who brushed their teeth twice daily, individuals who brushed less often than once a day experienced a significant multivariate hazard ratio of 1.7 for cardiovascular events. The adjusted hazard ratio among patients who brushed once a day was 1.3, a result of borderline significance.


• The risk for cardiovascular disease related to poor oral hygiene was similar among men and women, and it also did not differ by age or smoking status.


• Mean levels of CRP among participants who brushed twice daily, once daily, and less than once daily were 3.07, 3.51, and 4.18 mg/L, respectively. The respective fibrinogen levels were 2.86, 2.95, and 2.98 mg/L.


• Further analyses indicated that these markers of systemic inflammation at least partly mediated the risk for cardiovascular events associated with poor oral hygiene.

Clinical Implications

• A previous study found that serum levels of CRP and amyloid A protein, but not the white blood cell count or albumin level, were positively and independently associated with the risk for coronary heart disease events.


• The current study suggests that toothbrushing less than twice daily might independently increase serum markers of systemic inflammation as well as the risk for cardiovascular disease.