Learning Goals:
- Gain insight into the pathogenesis of periodontal disease.
- Explore the potential links between the mechanisms behind periodontal disease and cardiovascular health impacts.
- Differentiate between statistical markers and true cardiovascular risk factors.
- Identify the key modifiable and non-modifiable risk factors contributing to cardiovascular disease.
- Acquire knowledge about current studies—statistical, clinical, and longitudinal—that suggest a connection between periodontal disease and cardiovascular pathology.
- Understand the evolving role of dental professionals in educating and counseling periodontal patients about the possible risks of developing cardiovascular disease.
Suspicion of Co-Existing Health Conditions
Coronary heart disease accounts for over 500,000 annual deaths in the United States. Cardiovascular diseases are known to have several recognized risk factors, many of which are related to lifestyle—such as smoking, diet, alcohol consumption, and excessive body weight. These factors are considered modifiable. Recent scientific research has begun to suggest that periodontitis, as well as tooth loss due to poor oral hygiene and infection, could also serve as modifiable risk factors for cardiovascular conditions.
As dental professionals, we frequently encounter patients with significant periodontal disease who also exhibit varying stages of cardiovascular disease. Often, after a comprehensive medical history and patient consultation, we might observe a link between a patient's overall systemic health and their deteriorating oral health. It’s common to note that poor oral health might serve as a reflection of a patient's general physical state. Consequently, periodontitis is frequently seen as a symptom or consequence of more severe health issues.
Traditionally, systemic and cardiovascular diseases have been viewed as predisposing conditions that contribute to the development of periodontitis. However, what if this relationship operates in reverse? Increasing evidence supports the idea that periodontal disease may not just be a symptom, but an actual contributing factor or risk indicator in cardiovascular conditions, including atherosclerosis, heart attacks, and strokes. Statistical data highlights that individuals with poor dental health and inadequate care experience cardiovascular complications at higher rates compared to those receiving regular dental treatments. Studies have revealed a strong association between poor oral health and an elevated risk of heart attack or stroke.
Finnish research dating back to 1989 found that individuals with missing teeth and general oral deterioration had higher rates of cardiovascular disease. The hypothesis was that missing teeth and bone loss could be indicators of underlying oral bacterial infections. However, it remained unclear whether periodontal disease played a causal role in heart disease or was merely a concurrent condition.
The theory that oral bacteria could contribute to systemic infections has been around since the early 1900s. British physician Dr. William Hunter was one of the first to propose that infections in different organs might be linked to chronic oral infections caused by various microbes. Over time, it has been well established that dental diseases like caries, gingivitis, and periodontitis are among the most widespread chronic infectious conditions.
A similar breakthrough occurred in gastrointestinal medicine, where it was once believed that stress and excessive stomach acid caused gastric ulcers. However, it was later shown that the bacteria Helicobacter pylori was the primary cause, and antibiotics could successfully treat most ulcers. This shift in understanding parallels developments in dentistry, where links between oral bacteria and cardiovascular pathology are being uncovered.
In 1998, a significant connection between oral bacteria and cardiovascular health was made by Dr. Mark Herzberg at the University of Minnesota. His research showed that bacteria found in dental plaque could trigger fatal blood clots when introduced into the bloodstream. Though his studies were performed on rabbits, the implications for human health are significant. Additionally, Finnish studies found a notable link between Chlamydia pneumoniae infection in the oral cavity and heart disease.
Dental professionals are well aware of the life-threatening risks posed by bacterial endocarditis, which can result from oral Streptococci entering the bloodstream during dental procedures. This is a clear example of how oral bacteria can cause systemic infections and severe health issues in distant areas of the body. Yet, to support the theory of a causal link between oral bacteria and cardiovascular events, clinical evidence was needed. Research has now identified specific bacterial strains commonly found in both periodontal disease and cardiovascular conditions, providing critical insight into this relationship.
The Development of Periodontitis
Periodontitis is recognized as a multifaceted disease, with several pathological mechanisms at play. Research, such as that by Offenbacher and colleagues, has outlined the key elements involved in this process:
- Bacterial Invasion (Microbial Challenge): Throughout the day, an estimated 100 billion bacterial cells are consumed from saliva. With more than 300 bacterial species typically found in the mouth, over a dozen have been linked to the onset and progression of periodontitis, which is classified as an infectious disease. A majority of periodontitis cases are linked to gram-negative anaerobic bacteria. Plaque formation is fueled by glycoproteins from saliva that coat the teeth, enabling colonization by these harmful anaerobes. These bacteria not only enter the digestive system via saliva but can also invade the bloodstream through compromised periodontal tissues.
- Toxic Substances Released by Bacteria: Plaque bacteria release a variety of toxins and low molecular weight metabolites that actively degrade periodontal tissue cells. The presence of lipopolysaccharides on the bacterial cell walls plays a significant role by stimulating an immune response. These lipopolysaccharides have also been found to induce the release of von Willebrand Factor antigen, which is notably elevated in patients who have experienced heart attacks.
- Immune and Inflammatory Reaction: In response to bacterial invasion, the host’s immune system activates macrophages and monocytes, which release inflammatory cytokines. These cytokines, in turn, prompt the production of enzymes such as matrix metalloproteinases (MMPs) and prostaglandins. MMPs, particularly collagenase, contribute to the breakdown of collagen, the essential protein in periodontal tissue. Prostaglandins further exacerbate the disease by altering bone metabolism, leading to an increase in osteoclast formation and subsequent alveolar bone loss, which characterizes clinical periodontitis.
- Liver’s Role: In response to bacterial infection, the liver initiates what is known as the acute phase response. During this process, the liver produces substances such as C-reactive proteins, lipoproteins, and fibrinogen, all of which are now recognized as contributing risk factors to cardiovascular diseases.
Exploring the Connection Between Periodontal Disease and Cardiovascular Health
Recent clinical, longitudinal, and statistical findings, including Dr. Herzberg’s research on specific periodontal pathogens involved in cardiovascular events, have led to a fundamental shift in understanding periodontitis' broader health implications. Traditionally, it was assumed that individuals afflicted by both cardiovascular disease and periodontitis were either genetically predisposed to these conditions or shared lifestyle risk factors such as poor hygiene, excessive alcohol use, or smoking. However, emerging research has now identified distinct strains of oral bacteria as direct contributors to cardiovascular disease.
Through advanced microbiologic techniques such as polymerase chain reaction (PCR) and DNA typing, scientists have been able to detect specific bacterial strains present in the cardiovascular tissues of affected individuals. By analyzing tissue samples from cardiovascular surgeries, oral bacteria were found to be embedded within the fatty plaque on arterial walls. Haraszthy and colleagues revealed that the following bacteria were frequently identified within arterial plaques:
- Cytomegalovirus: Found in 38% of samples.
- Bacteroides forsythus: Identified in 30% of cases.
- Porphyromonas gingivalis: Present in 26% of tested samples.
- Actinobacillus actinomycetes: Detected in 18% of the cases.
- Chlamydia pneumoniae: Discovered in 18% of arterial plaque samples.
The presence of these oral pathogens in cardiovascular tissues suggests a direct role in both diseases' progression. It has been proposed that these bacteria, once they enter the bloodstream, trigger platelet aggregation, leading to cardiovascular complications. This mirrors the process seen in subacute bacterial endocarditis, where Streptococci infect heart valves. Additionally, it is believed that the same inflammatory responses these microbes elicit in the periodontal tissues could occur within the vascular system, exacerbating vascular damage and contributing to cardiovascular disease.
Periodontitis as a Cardiovascular Risk Factor
While several statistical studies have shown a strong association between advanced periodontitis and a higher risk of cardiovascular disease, many of these studies involved patient groups already diagnosed with cardiovascular conditions or were not longitudinal. As a result, these studies could only suggest that periodontitis and tooth loss serve as markers or indicators for cardiovascular disease development, without establishing a definitive causal relationship. To demonstrate causality, a long-term, randomized study across a diverse patient population was necessary.
One such study was conducted using data from 20,000 participants in the National Health and Nutrition Examination Survey (NHANES), who were not pre-screened for either cardiovascular disease or periodontitis. Dr. DeStefano's findings from this study indicated that, after adjusting for all other risk factors, individuals with periodontitis or tooth loss (edentulous) faced a 72% higher risk of developing cardiovascular disease compared to those without these conditions.
Supporting these findings, a similar study of U.S. veterans demonstrated that increased periodontal bone loss was linked to a higher likelihood of cardiovascular incidents, including strokes and heart attacks. This research showed that for every 20% reduction in alveolar bone height, the risk of cardiovascular disease increased by 40%. The study further suggested that routine radiographic monitoring of periodontal bone loss could serve as a predictive tool for future coronary and cerebral vascular events.
The connection between periodontal bone loss and stroke risk has been further examined in studies by Syrjanen, Grau, and Beck, which analyzed full-mouth radiographic surveys to correlate bone loss and missing teeth with stroke incidence. After adjusting for other risk factors, the studies revealed that individuals in their thirties who experienced tooth loss and significant bone loss were 2.8 times more likely to suffer a stroke than those with minimal or no bone loss.
These findings highlight the need for dental professionals to consider periodontitis as a modifiable risk factor for cardiovascular disease. Addressing periodontitis presents a valuable opportunity for dental teams to motivate patients toward better overall health through proper dental care. A particularly noteworthy study by Loesche and colleagues found that older veterans who received annual dental cleanings (prophylaxis) were 5 times less likely to experience a stroke compared to those who underwent cleanings less frequently.
Emerging Dental Considerations for Periodontitis and Cardiovascular Risk
The standard of care for screening patients at elevated risk for both periodontitis and potentially cardiovascular disease may soon involve routine chair-side plaque testing for gram-negative anaerobic bacteria. These bacteria are capable of hydrolyzing the peptide benzoyl-arginine naphthylamide (BANA). The BANA test, which works through a simple color change mechanism, detects three key gram-negative anaerobes commonly associated with periodontitis: P. gingivalis, B. forsythus, and Treponema denticola. Studies indicate that patients with higher levels of P. gingivalis and B. forsythus in gingival plaque are at an increased risk of heart attack.
Current clinical studies are evaluating the effectiveness of both mechanical and pharmaceutical interventions in controlling periodontal pathogens. Chlorhexidine rinses have long been a staple in periodontal therapy, and newer delivery systems like PerioChip® have demonstrated clinical success in reducing periodontal microflora and pocketing. Additionally, subgingival antibiotic treatments, such as the Atridox® system, are being used to target oral pathogens, either in conjunction with traditional root planing or as standalone treatments. Furthermore, systemic sub-antimicrobial doses of antibiotics, such as Periostat®, are being used to mitigate the systemic inflammatory damage associated with periodontitis. These treatments may potentially lower cardiovascular risk in addition to improving dental health.
Several studies are also examining systemic antibiotic regimens aimed at eradicating pathogenic bacteria to enhance both oral and cardiovascular health. Clinical trials utilizing Zithromax® are targeting Chlamydia pneumoniae, a strain linked to cardiovascular disease, with data suggesting that a brief Zithromax® regimen after an acute heart attack reduces the risk of future attacks. Other clinical trials involving metronidazole and doxycycline show promise in reducing periodontal pathogens within periodontal pockets.
In 1998, the American Academy of Periodontology issued a position paper recognizing periodontitis as a potential risk factor for systemic diseases. It is increasingly evident that the same pathogens and disease mechanisms driving periodontitis and tooth loss may also play a role in cardiovascular disease. Dental professionals must remain vigilant, recognizing their responsibility to educate and counsel patients about the potential cardiovascular risks linked to periodontal disease. Just as oral cancer screenings and nutritional counseling are integral to clinical practice, advising patients on the connection between periodontal disease and cardiovascular health is becoming an essential component of modern dental care.
Quiz For Considering Periodontitis as a Risk Factor for Cardiovascular Disease
