The Mouth−Body Connection

By Lea E. Erickson

Oral health contributes significantly to self-esteem and quality of life. The ability to smile without embarrassment, to articulate speech clearly, to taste and chew food, and to be free of pain are key for well-being. The high prevalence of dental caries (cavities) and periodontal (gum) disease is a major public health concern with attendant costs for treatment, loss of productivity, diminished comfort and function, and increased risks to systemic health.

Dental caries is a complex disease process resulting from a shift in the plaque biofilm on teeth in the presence of sugars. The microorganisms in this biofilm produce acids that demineralize the calcified tooth structure and, if the process is not disrupted, teeth are demineralized until a cavity forms. If untreated or uncontrolled, the caries process may affect the dental pulp, or tooth center, which is rich with vascular, nerve, and connective tissue, resulting in pain and infection.

Periodontal disease occurs when plaque (the biofilm with bacteria) is inadequately removed, and destructive inflammation results, affecting the soft and hard tissues (bone) supporting the teeth. Gingivitis is characterized by swelling and bleeding of the gingival tissues. When the inflammatory process progresses from gingivitis to periodontitis, it affects the periodontal ligament (the tissue that attaches the teeth to the bone) and the alveolar bone (the bone that supports the teeth), and can lead to recession, tooth mobility, and eventual tooth loss. Periodontitis affects more than 60 percent of older adults and is severe in 10 percent to 15 percent (Chapple and Genco, 2013). The bacteria, inflammatory mediators (molecules that play a role in inflammation), and antibodies that contribute to periodontitis enter the circulatory system and are carried to other parts of the body (Borgnakke, 2015); this represents a biologically plausible contributing factor to many systemic diseases.

Several studies have identified associations between oral health and chronic systemic diseases. According to the Centers for Disease Control and Prevention (CDC), chronic diseases such as cardiovascular disease, stroke, diabetes, arthritis, and cancer are responsible for 70 percent of U.S. deaths (CDC, 2016a). The complex associations between chronic systemic diseases and oral disease include common risk factors such as high sugar consumption, obesity (Slotwinski and Slotwinski, 2015), smoking, shared inflammatory pathways, access to the bloodstream via ulcerations of inflamed epithelium (Borgnakke, 2015), medications that increase the risk of oral diseases, and diminished function required to maintain oral health.

Data from a large insurance database showed high medical costs and frequent hospitalizations to be common in patients with diagnoses of type 2 diabetes, cerebrovascular disease, rheumatoid arthritis, or coronary artery disease and periodontal disease.Patients with these comorbidities who received periodontal therapy at least four times per year were compared with those who did not. The treatment group (approximately 1 percent) had significantly fewer hospital admissions and significantly lower medical costs than the non-treatment group for diabetes, cerebrovascular disease, and coronary artery disease (Jeffcoat et al., 2014).

The Periodontal Disease and Diabetes Connection

There is a public health imperative to conduct prevention and intervention programs for diabetes because there are more than 29 million people with diabetes and 86 million who are pre-diabetic in the United States, at a cost of $245 billion per year and a 50 percent increase in risk of death (CDC, 2016b). People with diabetes are at greater risk of developing periodontal disease and at risk for more severe disease. A bi-directional relationship between periodontal disease and diabetes is well established (Chapple and Genco, 2013). Poorly controlled diabetes increases the risk of periodontal disease, and the presence of periodontal inflammation contributes to poor glycemic control, the risk of developing type 2 diabetes, and diabetic complications (Chapple and Genco, 2013; Borgnakke, 2015).

Periodontal interventions such as professional debridement (teeth cleaning), antimicrobial therapy (through special mouth rinses or medications), or surgery could potentially reduce the risks associated with diabetes by improving glycemic control. A meta-analysis of fourteen studies demonstrated that periodontal intervention led to a 0.29 percent decrease in the HbA1c (a measure of glycated hemoglobin, i.e., oxygen bound to glucose in the blood, that indicates glycemic control across the prior three months) at three to four months that was not sustained at six months, suggesting the need for ongoing professional care. Some individuals require a three-to-six-month schedule for professional teeth cleaning, especially if the 0.29 percent decrease in HbA1c impacts glycemic control. No difference was evident comparing different therapies (Simpson et al., 2014).

In a joint statement, the European Federation of Periodontology and the American Academy of Periodontology recommended that patients with the diagnosis of diabetes (type 1 or type 2) should be advised that they are at higher risk for periodontal disease and that glycemic control will be more difficult and the risk of complications greater in the presence of periodontal disease. Such patients should have a comprehensive periodontal exam, be placed on a preventive program including extensive oral health maintenance education, and be monitored regularly for changes in periodontal status. If diagnosed with periodontal disease, they should have timely intervention and follow-up(Chapple and Genco, 2013).

Associations Between Cardiovascular and Periodontal Disease

Although the “Floss or Die” headlines overstated the strength of the evidence, subsequent studies have identified a significant and independent association between periodontal disease and cardiovascular/cerebral events related to atherosclerosis (Leng et al., 2015; Zeng et al., 2015). Atherosclerosis is the buildup of fats (cholesterol and triglycerides) and other substances in and on the walls of arteries that can eventually close the artery to blood flow. Periodontal pathogens (usually bacteria) might contribute to the development and destabilization of atherosclerotic plaque either directly by invasion of the vascular tissues, or indirectly through the release of inflammatory mediators (e.g., IL-1, IL-6, TNF-α, C-reactive protein) (Borgnakke, 2015; Nguyen et al., 2015). When these inflammatory mediators are released, the risk for a cardiovascular event or a stroke increases.

Arterial stiffness (arteriosclerosis), acting as an easily and non-invasively measured marker of atherosclerosis, is associated with periodontitis compared to controls (Nicolosi et al., 2016), but it was unclear how robust the association was after adjusting for confounding factors (Schmidtt et al., 2015).

Multiple studies have shown increased thickness in arterial walls in the presence of periodontal disease (Orlandi et al., 2014; Budzyński et al., 2015). The well-established association between periodontal disease and cardiovascular disease does not support a causal relationship, and studies to determine if periodontal interventions prevent or alter outcomes of cardiovascular disease are insufficient (Lockhart et al., 2012). However, evidence such as that from the aforementioned large insurance database demonstrating lower costs and fewer hospital admissions for patients with cerebrovascular disease and coronary artery disease demonstrate the need for well-conducted clinical trials (Jeffcoat et al., 2014).

In the absence of adequate randomized-controlled interventional studies that satisfactorily assess the effect of periodontal interventions on cardiovascular disease outcomes (Li et al., 2015), surrogate risk factors have been investigated, demonstrating that periodontal therapy reduces many of these risk factors—total cholesterol, low-density cholesterol, triglycerides, systolic and diastolic blood pressure, and left ventricular mass (Borgnakke, 2015). Left ventricular mass defines enlargement (hypertrophy) of the left ventricle of the heart; and this enlargement is a predictor of cardiovascular morbidity (diseases) and mortality. Jeffcoat and colleagues (2014) recommend that periodontal intervention of “modest cost and minimal risk” be integrated into the management of patients with chronic diseases.

Reducing Risks of Pulmonary Disease Through Oral Hygiene

Pneumonia accounts for more than a million hospital admissions and more than 50,000 deaths per year in the United States (CDC, 2016c), and is a major cause of morbidity and mortality in older adults (American Lung Association, 2016; Tada and Miura, 2012). Aspiration pneumonia is common in frail older adults with dysphagia (an abnormal swallow) and in ventilatordependent patients. Oral interventions, including mechanical plaque removal and chemical disinfection with agents such as chlorhexidine or povidone iodine mouth rinse reduce the risk for disease development and progression (Borgnakke, 2015).

Using effective oral hygiene in ventilated patients has demonstrated a reduction in the risk for ventilator-associated pneumonia (VAP). Although no reduction in mortality or length of time ventilated was identified, chlorhexidine (an antibacterial agent) rinses or gels reduced the odds of developing VAP by 40 percent (Shi et al., 2013). Tada and Miura (2012) recommend a strategy of intervening in multiple risk factors—by reducing the microbial load with effective oral hygiene, including mechanical cleaning by dental professionals and oral decontamination with antimicrobial agents such as chlorhexidine; and improving oral function with swallowing training and salivary stimulation. A correlation between tongue coating and aspiration pneumonia risk points to the benefits of including tongue cleaning as part of mechanical debridement (Abe et al., 2008).

Much of the literature focuses on preventing aspiration pneumonia, but oral hygiene might also affect other respiratory diseases. Older adults who attended adult daycare once a week were randomly assigned to either a group that received weekly oral hygiene delivered by a dental hygienist using toothbrushes, floss, and tongue brushes, or to a control group that performed oral hygiene independently and unsupervised. Despite the small number of persons who developed influenza, the study group demonstrated significantly lower risk of developing influenza compared to the controls (p = 0.008), suggesting that maintaining oral hygiene might be an effective strategy in preventing influenza in this population (Abe et al., 2006).

Shifting Antibiotic Recommendations in Post-Joint Replacement Patients

Rheumatoid arthritis is an autoimmune disease associated with significant morbidity and early mortality. Chronic inflammation causes pain, joint deformity, and loss of function in multiple joints and other organs (CDC, 2016d). Because both rheumatoid arthritis and chronic periodontitis are inflammatory diseases, an association has been investigated. A systematic review and meta-analysis demonstrated a significantly increased risk for periodontitis in subjects with rheumatoid arthritis compared to healthy controls, but not when compared to subjects with osteoarthritis (Fuggle et al., 2016). Because the study investigated risk for periodontal disease and no difference was identified between rheumatoid osteoarthritis and osteoarthritis, the increased risk might be explained by reduced functional ability to perform adequate oral hygiene procedures.

Read More from the Fall 2016 Issue of Generations

Older Health and Older Adults: A History of Public Neglect

Growing the Dental Workforce to Serve Rural Communities: University of Washington’s RIDE Program

Oral Healthcare Advocacy: Finally on the Upswing

The Gary and Mary West Senior Dental Center: An Integrated Model of Dental, Health, and Wellness Care for Older Adults

Another systematic review investigated the effect of conservative periodontal interventions on rheumatoid arthritis symptoms and periodontal outcomes. The erythrocyte sedimentation rate, a blood test that assists in diagnosing, inflammatory diseases and in monitoring their progress, was significantly reduced after treatment, and other inflammatory markers trended toward improvement (Silvestre et al., 2016).

Nearly 50 percent of American older adults have a diagnosis of arthritis, and in 2011 surgeons performed more than 750,000 total knee replacements and more than 500,000 total hip replacements (CDC, 2016e). It is projected that there will be more than 3.48 million total knee replacements by 2030 (Shahi and Parvizi, 2015). Prosthetic joints improve function, reduce pain, and improve quality of life, but are not without complications. A most challenging complication is the periprosthetic joint infection (PJI) with associated costs and surgical risks. Certain dental procedures such as periodontal interventions and surgery create a transient bacteremia, and the resulting bacteremia has been considered a potential causal factor for PJI. It is common to recommend antibiotic prophylaxis for dental procedures in patients with prosthetic joints.

In 2012, the American Academy of Orthopaedic Surgeons and the American Dental Association (ADA) completed an extensive review of the literature and produced an evidence-based clinical guideline that did little to clarify the relative risks and benefits of using prophylactic antibiotics, and even appeared to increase recommended dental procedures to consider for pretreatment prophylaxis (Sollecito et al., 2015; Rethman et al., 2013).

In 2014, the ADA updated the 2012 literature search and concluded that patient risk factors for PJI were independent of dental procedures and that the risks for antibiotic resistance, adverse drug reactions, and the cost of the drugs outweighed the benefit (Sollecito et al., 2015).

They added the caveat that a final decision on prophylaxis should include a complete assessment of the patient’s medical status, and suggested consultation with the patient’s orthopaedist prior to prescribing antibiotics. The controversy continues as some authors question the conclusions reached by the 2014 panel of the ADA, and although some data demonstrate that antibiotic prophylaxis may not be cost-effective, other data recommend consideration of coverage based on the patient’s risk factors, especially if immuno-compromised, and on the complexity of the dental procedure (Shahi and Parvizi, 2015; Slover et al., 2015; Friedlander et al., 2015).

Many older patients have salivary hypofunction (produce less saliva) to varying degrees secondary to medications, diabetes, autoimmune disorders, and other reasons. Saliva is essential to maintaining oral tissue health. Saliva initiates digestion, lubricates tissues, aids in mastication and bolus formation, affects taste, and maintains tooth integrity (buffering, antibacterial, antiviral, antifungal, and reservoir of calcium and phosphate ions for remineralization). Xerostomia contributes to dental caries—especially root caries, fungal infections, mucositis, dysphagia, poor denture retention and discomfort, speech difficulty, and increased risk for periodontal disease.

As a complex bodily fluid with multiple functions, the best strategy for managing a dry mouth is to stimulate as much salivary flow as possible. Medications for Sjögren’s syndrome and radiation-induced hyposalivation are available (pilocarpine hydrochloride and cevimeline). Sugarless gum and candy stimulate salivary flow and are readily available and palatable to most patients. They have the added advantages of replacing fermentable carbohydrates, and the polyols that sweeten them may have a direct anticariogenic effect (Burt, 2006). The caries associated with dry mouth are extremely difficult to control, so all prevention means available should be considered, starting with an effective program of patient education combined with the use of home and professionally applied fluoride products.

The emerging body of evidence linking oral disease and systemic disease underscores the necessity of collaborative patient care (with dental health professionals being included as an integral part of a healthcare team), and an aging population requires a systematic approach to maintaining health.

Lea E. Erickson is associate professor and section head, Patient Assessment and Treatment Planning, School of Dentistry, University of Utah Health Sciences, in Salt Lake City.


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Editor’s Note: This article is taken from the Fall 2016 issue of ASA’s quarterly journal, Generations, an issue devoted to the topic “Aging and Oral Health.” ASA members receive Generations as a membership benefit; non-members may purchase subscriptions or single copies of issues at our online store. Full digital access to current and back issues of Generations is also available (and free of charge to ASA members and Generations subscribers) at Ingenta Connect.

Support for the Fall 2016 issue of Generations, “Aging and the Importance of Oral Health,” was provided by the Gary & Mary West Foundation.