Interwoven

I recently received a call from a family practice physician, Dr. B. He said that for the past two years he has been treating a 62-year-old woman named Sally for a facial infection with a fistula draining from her left cheek. Several CT scans and MRIs had not identified the cause, and multiple rounds of antibiotics had not resolved the lesion. Finally, a radiologist suggested that the etiology might be dental. Dr. B. asked Sally about her dentist, and she mentioned my name, so he picked up the phone to request that I take a look.

I remembered Sally right away. I had referred her to an endodontist— more than two years before—for an abscess on her lower left second molar. I hadn’t seen her since.

A periodical radiograph confirmed the issue, and an uncomplicated extraction healed the fistula, leaving a small, lumpy white scar at the base of her jaw. I asked Sally why she had gone to her medical doctor instead of to the endodontist. “I don’t have dental insurance,” she said. “But I have a medical plan.”

Dr. B. and I share a patient who clearly believes that a doctor is a doctor. Yet—not even accounting for specialization—in focus and scope, as well as in education, insurance provisions, networking systems, recordkeeping, political interests and professional traditions, American medicine and dentistry are miles apart.

The medical-dental divide may be less conspicuous in other locales. When I worked, right after my Dugoni School graduation, as a medecin-dentiste stagiaire in a Swiss teaching hospital polyclinic, the surgery department routinely sent patients over to the dental service for consultation, evaluation and treatment prior to an operation. But in the United States, the gap between dental and medical sensibilities—and communication—remains as stark as my patient’s suppurating ulcer.

“Doctors are doctors, and dentists are dentists, and never the twain shall meet,” Julie Beck writes in “Why Dentistry is Separate from Medicine,” in The Atlantic (March 9, 2017). “Whether you have health insurance is one thing, whether you have dental insurance is another. Your doctor doesn’t ask you if you’re flossing, and your dentist doesn’t ask you if you’re exercising.”

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Several historical wrinkles, fueled, perhaps, by ancient demands of pride, status, independence, social convention, legislation and money, may explain the rift, including the rejection of a proposed dental curriculum at University of Maryland’s medical school in 1839, leading to the founding of the first independent dental school, the Baltimore College of Dental Surgery, in 1840. Years later, there was the wholesale disregard of recommendations in the 1920s to merge dentistry with medicine; and then the rise of health insurance in the 1930s, which designed medical plans, deemed a necessity, to fund large, unpredictable expenses, and dental coverage, considered an optional benefit, to subsidize predictable, lower-cost preventive measures.

As a result of these and other distributive workforce trends, medical and dental disciplines evolved to practice in remarkable isolation from each other. When a medical provider examines a patient for diabetes, for example, and a dentist diagnoses periodontal disease, no one, least of all the doctors, typically thinks they ought to collaborate. But, of course, they should. The human body keeps its concatenated parts interacting with each other regardless of what administrative separations the various treatment purveyors may declare. Disease states notoriously refuse to stay inside the lines.

Expanding knowledge has made our corporeal interconnectedness increasingly plain. Research in the 1980s, which substantially increased in the 1990s, began to reveal biological links between oral and systemic maladies—periodontitis with diabetes, for example, and periodontitis with cardiovascular disease. In 2000, the United States Surgeon General David Satcher declared, “Without oral health, you’re not healthy.” The general public even started getting the memo; patients came into my practice requesting prophies to prevent a heart attack.

Continuing research shows consistent evidence for mouth-body relationships: oral disease- causing bacteria can colonize in other parts of the body and trigger inflammatory responses and illness beyond the mouth. A September 2024 study, for instance, published in the American Medical Association’s JAMA Oncology found oral bacteria implicated in head and neck squamous cell carcinoma. Other studies suggest that the oral microbiome— particularly a dysbiosis, or imbalance, therein—may affect the SARS-CoV-2 virus, HIV, prostate health and even aging.

Drs. William Lundergan ’81, Kavitha Parthasarathy and Navid Knight ’89 of the dental school’s Department of Periodontics published a paper this year, “Periodontitis and Alzheimer’s Disease: Is There a Connection?” (Oral January 2024, 4, 61-73), in which they were able to draw a line from gum disease to dementia: “It seems clear,” they write, “that periodontal pathogens and/or their virulence factors can enter the brain via vascular or neural pathways. It also seems clear that these pathogens can stimulate a neuroinflammatory response that could lead to neurodegeneration and subsequent cognitive impairment.”

Dr. Parvati Iyer, assistant professor in the Department of Diagnostic Sciences and course director of Integrated Clinical Sciences II, published a 2023 paper in the Journal of the California Dental Association, Volume 51, titled, “Oral Cavity is the Gateway to the Body: Role of Oral Health Professionals: A Narrative Review.” This May, she gave a presentation at the California Dental Association (CDA) meeting in Anaheim titled, “Oral Gut-Brain Axis and You—Paradigm Shifts for Optimal Health,” and a July talk at the school titled, “Flossing for Your Heart: Oral Health’s Ripple Effect.”

Iyer sent me a schematic showing microbes associated with periodontitis, caries, diabetes, pancreatic cancer, rheumatoid arthritis, esophageal cancer, colorectal cancer, cystic fibrosis, cardiovascular disease and Alzheimer’s disease. “Please note,” she wrote, “that P. gingivalis is listed on all the systemic diseases!” Iyer’s CDA paper reports that P. gingivalis is also present in gastrointestinal, genitourinary and liver diseases and autoimmune diseases, including systemic lupus erythematosus and Sjogren’s syndrome.

Much of this incitement to illness is inflammatory and related to periodontal disease. As Lundergan, professor and chair in the Department of Periodontics, explains, “A susceptible host experiences a subgingival bacterial dysbiosis, leading to periodontitis, which in turn results in a hyperinflammatory response: the injured tissue—which, in the case of generalized perio, when you consider the totality of all those pockets, involves significant surface area—releases pro-inflammatory mediators: cytokines, host-derived proteinases and prostaglandin E2. Bacteria, bacterial fragments or bacterial byproducts, along with these pro-inflammatory mediators, may enter the bloodstream and migrate to different parts of the body, where they exert their effect locally.”

But naturally, it’s complicated. Nearly half of adults over age 30 suffer from periodontal disease, and while an unmistakable link exists between periodontitis and various systemic conditions, including cardiovascular disease; diabetes; respiratory infections; rheumatoid arthritis; Alzheimer’s disease; pre-term, low-birthweight babies; and chronic inflammatory bowel disease, it’s not always obvious what leads to what. Mouth-body disease connections may be casual—or causal.

Studies show that many dental procedures, including periodontal probing, scaling and root planing, tooth extraction and restorative procedures, can admit bacteria into the bloodstream. Even eating and brushing teeth can produce bacteremias that last more than 30 minutes. Yet the mouth may also serve as a simple physical conduit for the development of infections, ulcers, pneumonia and cancer when, during breathing and swallowing, external microbes dive into the digestive and respiratory tracts.

What’s more, periodontal disease and certain chronic systemic conditions, including heart disease, stroke and diabetes, share risk factors such as smoking, poor diet, obesity, high blood pressure or high LDL (“bad” cholesterol). In the case of some systemic conditions, particularly diabetes, the relationship seems to be bi-directional— diabetes increases the risk for periodontitis and periodontitis increases the risk for diabetes.

The recognition of certain oral-systemic linkages has already yielded useful results. “One of the biggest concerns we see is the connection with oral health and diabetes,” says Dr. Kim Benton, assistant professor in the Department of Diagnostic Sciences and director of the new Pacific Health Care Collaborative. “The good news is when we treat the periodontal condition, we begin to see an improvement in diabetes.”

“The bottom line is that we are analyzing the existing research and trying to understand it further,” Iyer says, “especially in light of the emerging field of personalized medicine. We should always ask the question, ‘Why does a specific treatment work for some and fail for others?’”

A lack of complete clarity is certainly no reason to shrug off the multitude of bodily networks. Oral health by itself forms a critical chunk of overall health. “While a definitive and direct cause and effect would be helpful in prevention and treatment, known associations between organ system diseases cannot be dismissed because they all exist in the same vehicle,” says Dr. Elisa M. Chávez, professor in the Department of Diagnostic Sciences and director of the Pacific Center for Equity in Oral Health Care. “So oral health has to be included as part of a bigger picture, and these associations—between oral and systemic disease and the social determinants of health—must not be dismissed or understated, as the implications of inadequate oral health care, with or without an identified direct cause and effect, can be significant to an individual and to public health.”

As understanding of these oral-systemic ties deepens, so does the potential for improved care, and, in turn, health care providers’ responsibility—which encompasses a duty to collaborate across the professional spectrum. “Our understanding of these links places a burden on dentists and our physician colleagues to work together for the better treatment of our patients,” Lundergan says. “I believe that integrated care is the key to better outcomes.”

“Simply put, health equity cannot be achieved if oral health is left out of the equation,” Chávez says. “At an individual level most people would likely be able to articulate how dental pain and missing teeth negatively impact their overall health and well-being. But there is still a disconnect within the healthcare system and among the general public in that individuals don’t realize the risks their chronic diseases and medications can hold for their oral health, and the associations between poor oral health and chronic diseases are often minimized.”

Dental students at the Dugoni School are being trained to shrink that disconnect. “Our students are exposed to the oral health-systemic health link across our Helix curriculum,” Lundergan says. “Primary exposure is during the first two years of the curriculum in the Integrated Biomedical Science and Integrated Clinical Science strands where students learn about the link and its implications for patient care. Our Pacific Health Care Collaborative (PHCC) in Sacramento is in many ways the result of this link and the recognition that medical care providers and dental care providers need to work together to provide optimal care for patients.”

Benton says that the most important aspects of dental-medical behavioral integration include improving health outcomes at lower cost for more people, as providers learn from each other. Serving that objective, PHCC aims to provide a “one-stop shop,” including an ambulatory surgical center to address dental and medical needs of patients, such as those having developmental and intellectual challenges, who require full sedation. PHCC’s programs are designed to create teaching conditions in which students can truly come together, in learning with and from each other.

Chávez points out that merging disparate healthcare systems requires, among other advances, policy changes, including legislative funding, to adequately support treatment, research and education that will promote further understanding of the oral-systemic connection to improve outcomes. It may seem like a tall order, but the kind of integration that Dugoni School professors dream of could be closer than we think. Look how far we’ve already come.

Eric K. Curtis ’85, DDS, of Safford, Arizona, is a contributor to Contact Point and is the author of A Century of Smiles, a historical book covering the dental school’s first 100 years.