Patty and Dr. Paul Levi

Patty Levi has supported Paul for nearly fifty years in his endeavor to teach and practice periodontology. Levi has been a part-time lecturer at HSDM for 30 years and also serves as an adjunct lecturer at Tufts. He has an accomplished career as a periodontologist, teacher, researcher, and mentor. He’s lectured in U.S. dental schools as well as in Barcelona, Spain, where he taught at the Universitat Internacional de Catalunya and was recognized by the university with an honorary doctorate degree. He was also named Clinician of the Year by the Massachusetts Dental Society. They are very honored to have this named program and feel strongly that it will enhance the knowledge of preventive dentistry and periodontology to students and to the public.

“Put the mouth back in the body.”

Dean Bruce Donoff (1942-2025), DMD67 Harvard School of Dental Medicine, MD73 Harvard Medical School

Dr. Bruce Donoff, a dentist, a physician, and the Dean of Harvard School of Dental Medicine for nearly three decades, recognized that many physicians and dentists do not treat oral infections as if they were systemic diseases. The untimely passing of Dean Donoff, as 2025 neared its end, served as an inspiration to continue research into the oral-systemic link about which he was so passionate, and to which he dedicated so much of his illustrious career. He used the phrase “put the mouth back in the body” to emphasize that oral health is not separate from overall health and pointed out that poor oral health is not “just a tooth problem.” He noted links between oral inflammation and conditions such as diabetes and cardiovascular disease.¹ Dr. Donoff stated that this connection necessitates combined medical-dental thinking, and he believed that separating dentistry from medicine reduces the results of patient care for the patient and the clinician and blocks meaningful collaboration.²

The definition of a systemic disease in Dorland’s Illustrated Medical Dictionary is, “a disease that involves multiple organs simultaneously as the main disease process (e.g., diabetes, rheumatoid arthritis, lupus, scleroderma, etc.)”³. Medicine and dentistry do a great disservice to their patients when the definition of a systemic disease is so narrowly defined. Medical textbooks provide the definition of a systemic disease by illustrating examples of specific systemic diseases that affect multiple organ systems^4,5.

Using the above criteria, periodontal and peri-implant infections along with dental caries involving the pulp (nerve) are not considered systemic diseases, because their primary pathogenesis originates locally within the periodontal and peri-implant tissues, a single organ, and they do not usually have immediate effects on other organs.^6-10 “Systemically healthy” also implies that periodontal findings are not influenced by known systemic modifiers. However, “Patients with periodontitis were found to have a notably higher chance of developing heart infections, cardiovascular diseases, head and neck cancers and overall mortality over nearly two decades of follow-up.”¹¹ Even though these oral infections, caused by dysbiotic bacteria, contribute to a systemic inflammatory burden, endothelial dysfunction, immune priming, and are associated with multiple systemic conditions, their initiation, progression, and clinical management are organ-specific and usually do not have immediate effects. Thus, they are described as localized chronic infections with systemic consequences rather than primary systemic diseases. The 2017 World Workshop (AAP/EFP) classifies periodontal and peri-implant diseases as diseases [infections] of the periodontium and peri-implant tissues, not as systemic diseases.¹² This definition is far too narrow and, as such, is harmful to clinicians and patients alike.

In two recent articles in the Journal of Periodontology, the enrollment of subjects was described in the methods section in the following manner, “A total of 75 systemically healthy nonsmokers were enrolled, of whom 23 had stage III periodontitis…”¹³. The other article described their subjects as being, “Systemically healthy participants with periodontitis…”¹⁴. What is being suggested to the readers is that periodontal and peri-implant infections are not systemic diseases. However, “Periodontitis is a chronic multifactorial inflammatory disease associated with dysbiotic plaque biofilms and characterized by progressive destruction of the tooth supporting apparatus.” ^15,16. This commonly understood definition raises questions. Have we separated oral health from systemic health, and what does systemically healthy truly mean?

From an academic viewpoint, when reporting research, describing subjects as systemically healthy is intended to mean that the subjects have no diagnosed systemic diseases that would confound the results of that particular study. However, the implication for the reader may be otherwise, implying that oral infections are not related to overall body health. It is clear that periodontal and peri-implant diseases can impact systemic conditions^17-20, and labeling subjects with stage III periodontitis as “systemically healthy” suggests that oral infections such as periodontal infections do not affect general health and vice versa.

Inflammatory periodontal and peri-implant diseases are chronic and sometimes acute infections associated with toxic biofilm, the by-products of bacterial metabolism, attached to a non-shedding surface (the tooth or a dental prosthesis). Dysbiotic biofilm represents a shift in bacteria from a symbiotic to a pathologic microbial community, which is driven by and sustained by chronic inflammation²¹. The inflammation exerts effects beyond the oral cavity by creating and continuing a chronic host immune response. Dysbiotic subgingival or peri-implant biofilms continuously stimulate innate and adaptive immunity via pattern-recognition receptors, leading to persistent production of pro-inflammatory mediators such as IL-1β, TNF-α, IL-6, prostaglandins, and matrix metalloproteinases. Locally, this non-resolving inflammation causes destruction of gingival/peri-implant connective tissues and pathologic bone resorption largely mediated by RANKL-driven osteoclastogenesis, with peri-implant sites often exhibiting more rapid bone loss due to the absence of a periodontal ligament and reduced vascular supply. Systemically, inflammatory mediators and bacterial products can enter the circulatory system, increasing the overall inflammatory burden, altering endothelial function, impairing metabolic regulation, and priming immune responses at distant sites. Thus, while periodontal and peri-implant diseases are not causative or primary in other organs, they function as chronic inflammatory stressors that can modify systemic immune homeostasis and contribute to the severity or risk profile of other inflammatory conditions in susceptible individuals^{22, 23}.

The literature clearly states that periodontal and peri-implant diseases contribute to a systemic inflammatory burden through locally produced cytokines which enter the systemic circulation and can elevate C-reactive protein (CRP). Key systemic co-morbidities include diabetes mellitus²⁴, cardiovascular diseases^25-26, adverse pregnancy outcomes^27-28, rheumatoid arthritis^29-30, respiratory diseases^31,32, chronic kidney disease³³, cancer^{34, 35}, obesity and metabolic syndrome^36-38, bowel disorders (IBD)³⁹, emotional and quality of life issues^40-43, and Alzheimer’s disease⁴⁴. Patients with periodontal and peri-implant infections often experience transient bacteremia during mastication, as evidenced by periodontal pathogens or bacterial DNA having been found in distant tissues (e.g. atheromas). Periodontal diseases have been widely associated with systemic diseases through epidemiological, mechanistic, and clinical research. However, because most of these associations are epidemiologic and have not been shown to be causal, and because many share common risk factors, they do not meet the criteria for labeling periodontitis itself as a systemic disease. Although not all relationships are proven causal, there is substantial evidence supporting links between periodontitis and systemic health outcomes^24-44.

It appears that these definitions, being taken literally is “splitting hairs”, and obscuring the truth about oral infections. When talking about periodontal/peri-implant infections, they are organ-specific and generally do not have an immediate effect on other organs. However, in addition to their systemic effects on the immune system, subsequent tooth loss negatively impacts mastication and can affect systemic health through impaired nutrition. Additionally, patients’ aesthetics are negatively impacted by affecting the individual’s psychological self-image and well-being ^39-42.

Should the present definition of a systemic disease, which includes only those involving multiple organs or having immediate and direct effects be taken so literally? Clearly, the definition of a systemic disease should be broadened to include diseases affecting a single organ with immediate or long-term effects on other organs. Chronic periodontal/peri-implant infections then will be considered as systemic, which will positively affect our medical and dental colleagues, our patients, and the entire medical community, by underscoring the potential seriousness of oral infections.

Dentists must be cognizant that bleeding on gentle probing around natural teeth and implants is indicative of a systemic infection and therefore must be taken seriously. Motivating and instructing patients with evidence-based plaque removal techniques^45-46and encouraging them to be seen for periodic professional dental hygiene therapy (PDHT) is essential to help eliminate and prevent periodontal/peri-implant infections as well as dental caries. Additionally, when placing dental implants, clinicians must strive to position implants so that the patient can effectively complete daily biofilm removal.

Physicians treating chronic medical problems, such as diabetes mellitus, cardiovascular diseases, rheumatoid arthritis, respiratory diseases, cancer, chronic kidney diseases, and metabolic syndrome, should be encouraged to work with dentists to rule out and control chronic oral infections. In the future integrated medical and dental records will allow dentists and physicians to have the necessary information to ensure that their patients have pertinent comorbidities controlled. In the meantime, the self-reported medical and dental histories will need to be verified by the clinicians.

In 2017 Tonetti et al. stated, “Periodontal diseases are highly prevalent worldwide and represent a major public health burden, affecting oral health, nutrition, and overall wellbeing. They are largely preventable and treatable, yet under diagnosis and limited access to care contribute to substantial personal, societal, and economic consequences. Effective prevention, early detection, and management strategies are urgently needed to reduce their global impact.”⁴⁸

Dean Donoff’s core belief throughout his career was that medicine and dentistry should not be siloed disciplines, but rather components of an integrated health care system. It is time that the definition of systemic diseases be broadened. Regardless of the location of the disease, a single organ or multiple organs, and whether the effects are immediate or long-term, those criteria should not affect their classification. Oral infections, including dental caries involving the pulp, periodontal, and peri-implant diseases, must be classified as systemic diseases (infections) to signify their importance in the wellbeing of our patients.

On December fifth, 2026, the Harvard School of Dental Medicine will host the Second Global Prevention Symposium with the theme of this meeting “The oral-systemic connection”. It will bring together physicians, dentists, medical and dental students, allied health professionals, and students working together to put the mouth back into the body. The proceedings will be available in person and online. Please join us!

References

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