More Evidence Links Gum Disease to Stroke Risk

January 19, 2018

A new study has strengthened the link between gum disease and increased risk for future stroke, showing a graded relationship with the extent of gum disease and stroke risk, and in addition finding that regular dental care was associated with a lower stroke risk.

"This effort is one of the largest, US-based community studies of periodontal disease, dental care utilization, and ischemic stroke," lead author, Souvik Sen, MD, University of South Carolina School of Medicine, told Medscape Medical News.

"Our results show that individuals who regularly attend the dentist had half the stroke risk of those who do not receive regular dental care," he said. "And our study of periodontal disease showed the more severe this is, the higher the risk of future stroke."

In particular, periodontal disease characterized by increased inflammation had the strongest association with stroke risk. "The risk conferred by gum disease is similar to that of high blood pressure —  it is in the range of two to three times increased risk," he added.   

The relationship between gum disease and myocardial infarction is already well established, and previous studies have shown an association between gum disease and stroke, he said. "Our current results strengthen that link. If causal, these associations would be of great importance because of the potential that periodontal disease treatment could reduce the stroke risk.

"It appears that good dental hygiene can do more than just keep your teeth and gums healthy — it may also lower your risk of heart disease and stroke," Dr Sen said. "Our results emphasize the need for good regular dental care, including a thorough home cleaning routine with brushing and flossing and then regular dentist and hygienist visits."

The study was published online in Stroke on January 15.

The researchers note that periodontal disease is a chronic inflammatory disease caused by bacterial colonization that affects the soft and hard structures that support the teeth. The prevalence of periodontal disease is high, with gingivitis or periodontitis affecting up to 90% of the population worldwide. About half of Americans aged 30 years or older have periodontitis, the more advanced form of periodontal disease.

Observational studies have shown that poor periodontal health status is associated with an increased stroke risk, but the authors point out that individual studies have limitations, including the use of many differing definitions of periodontal disease, consideration of potential cofounders (such as socioeconomic status), and low statistical power.

For the current study, the researchers used new definitions of seven distinct periodontal profile classes ranging from health (A) to severe periodontal disease (G), which has been validated in three large cohorts, to examine the relationship between periodontal disease and stroke. They also looked at particular stroke subtypes and adjusted result for confounders.  A separate analysis looked at the relationship between dental care and stroke risk.

The researchers analyzed data from 10,362 middle-aged individuals without a previous stroke participating in the ARIC (Atherosclerosis Risk in Communities) study of the causes of atherosclerosis and clinical sequelae who were recruited in the 1980s and underwent regular follow-up.

Participants were asked about dental care use, which was classified as regular (those who sought routine dental care more than once a year) or episodic (who attended the dentist only when they were in discomfort, when something needed to be fixed, or never).

During the 15-year follow-up period, 584 participants had an incident ischemic stroke.

Results showed that compared with the episodic dental care users, regular dental care users had a lower risk for ischemic stroke (crude hazard ratio [HR], 0.52; 95% confidence interval [CI], 0.44 - 0.61). After adjustment for race/center, age, sex, body mass index, hypertension, diabetes mellitus, low-density lipoprotein level, smoking, and education, regular dental care use continued to be associated with lower rates of ischemic stroke (adjusted HR, 0.77; 95% CI, 0.63 - 0.94).

For the periodontal disease part of the study (the dental ARIC study), 6736 individuals underwent a comprehensive dental examination, questionnaire, and sample collection at their fourth clinic visit. Of these, 299 went on to have an incident ischemic stroke in the follow-up period.

Compared with the reference healthy group without periodontal disease (PPC-A), those with periodontal disease had a higher risk for incident ischemic stroke that rose with severity of the gum disease.

Table. Stroke Risk by Periodontal Disease Status

Periodontal Profile Class Adjusted Hazard Ratio for Stroke Incidence Rate for Ischemic Stroke/1000 Person-Years
A (reference) 1 1.29
B (mild periodontal disease) 1.86 2.82
C (high gingival index score) 2.06 4.80
D (tooth loss) 2.03 3.81
E (posterior disease) 2.22 3.50
F (severe tooth loss) 2.08 4.78
G (severe periodontal disease) 2.20 5.03
Results adjusted for race/center, age, sex, body mass index, hypertension, diabetes mellitus, low-density lipoprotein level, smoking, and education.

 

The researchers point out that the inflammatory characteristics differ among the periodontal disease classes, which are defined by levels of attachment. The highest rate of stroke was seen among those with PPC-C (gingival inflammation) and PPC-G (severe disease), which are the most inflamed classes.

"Thus, inflammation plays a critical role in defining the risk for incident events," they state.

They elaborate: "What emerges from this investigation is that high gingival inflammation in the absence of severe periodontal disease (PPC-C) and the highly inflamed severe periodontitis class (PPC-G) are at higher risk than those with mild, moderate, or posterior disease patterns (all have less inflamed periodontal tissues). These data emphasize the importance of inflammation rather than just the level of attachment as being the main determinant of risk."

Further analysis showed a significantly increased hazard of cardioembolic stroke (HR, 2.6) and thrombotic stroke (HR, 2.2), but not of lacunar strokes, among study participants with periodontal disease.

"We believe the mechanism is to do with atherosclerosis and/or atrial fibrillation," Dr Sen said. "Others have previously shown a link between gum disease and atherosclerosis. Bacteria from the gums have been found in atherosclerotic plaques in both the carotid and coronary arteries."

He noted that a trial is now investigating whether increased periodontal care can reduce stroke risk. The PREMIER trial includes patients with gum disease who have already had a stroke or transient ischemic attack and so are at a high risk for another one. These patients are being randomly assigned to standard or intensive periodontal treatment.

The ARIC study is supported by grants from the National Heart, Lung, and Blood Institute. The dental ARIC study was supported by a grant from the National Institute of Dental and Craniofacial Research. Three coauthors ( K. Moss, Dr Beck, and S. Offenbacher) are seeking intellectual property protection for the periodontal profile class concept. Dr Gottesman is an associate editor of the American Academy of Neurology. The other authors have disclosed no relevant financial relationships.

Stroke. Published online January 15, 2018. Abstract

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