Periodontal Medicine—Changing the Face of Dental Care

In the past decade, the link between oral infection and certain systemic disorders has taken center stage. This possible relationship has garnered attention in the mainstream press as well in dental academia, prompting research efforts by many of the most highly regarded dental researchers in the United States and Europe. The discipline that explores the risks of oral infection in systemic diseases—from preterm low birth weight to diabetes—is broadly defined as periodontal medicine.

Understanding the difference between the long-recognized oral effects of systemic diseases and periodontal medicine is important. For example, patients undergoing chemotherapy for certain types of cancer may experience gingival bleeding and ecchymotic (small, flat hemorrhagic) areas on the mucosa because the number of circulating platelets in their bloodstream is reduced. A number of autoimmune disorders, such as the blistering diseases pemphigus and pemphigoid, often present in the oral cavity. Also, some medications can cause changes in oral tissues, like the anticonvulsant drug phenytoin and the immunosupressive agent cyclosporine, which can both cause gingival overgrowth. These are all examples of the effects of disease on oral health and should not be confused with periodontal medicine.

Periodontal medicine looks at the risk for certain systemic diseases that is increased by an oral infection (periodontitis) or from patients’ inflammatory response to the infection. Periodontitis is a chronic infection that may progress symptom-free for several years prior to diagnosis and even for patients aware of their diagnosis, compliance with treatment recommendations is often limited.

In a periodontal pocket, bacterial biofilm is in direct contact with an ulcerated epithelium, so the pathway to the systemic circulation is obvious. In patients with moderate to severe periodontitis, the total area of pocket epithelium in direct contact with the subgingival biofilm is estimated to be about the size of the palm of the human hand.¹ So gram negative bacterial substances and live bacteria have easy access to the connective tissue and blood vessels. This systemic challenge has the potential to affect tissues and organs at distant sites.

Furthermore, the diseased periodontium serves as a reservoir of pro-inflammatory mediators (molecules that enhance the inflammatory response) that can also enter the systemic circulation and induce and/or perpetuate systemic effects. These two pathways individually or, most likely, in combination may account for the various systemic effects of periodontal infections on cardiovascular health, the developing fetus, diabetics, and the respiratory health of elderly patients.

CARDIOVASCULAR/ CEREBROVASCULAR (CV/CV) DISEASE

The relationship between CV/CV disease and infection and inflammation is receiving particular attention. It is not known whether the association results from the infection directly or from the subsequent inflammatory response. However, the changes caused by infection and/or the inflammatory response are believed to affect the build-up of plaque on the inner lining of the blood vessels supplying the heart (coronary arteries) or brain (carotid arteries) that occurs in atherosclerosis.

Clinical studies have examined the risk generated by periodontitis for CV/CV disease. In these studies, the risk was independent of other known risk factors, including smoking and the blood lipid profile.^2,3 Upon investigating the national survey of health conditions of the United States population collected from 1988 to 1994 (NHANES III database), a relationship between periodontal attachment loss and the risk for myocardial infarction was demonstrated.⁴ Plus, a relationship between periodontal disease and tooth loss and subclinical measures of CV/CV disease has been recently reported.^5,6 Collectively, these data suggest a real and important influence of periodontitis on the risk for CV/CV disease.

However, the data are not absolute.^7-9 Furthermore, a randomized, controlled clinical trial demonstrating an effect of periodontal therapy on CV/CV disease has not been performed. A study to evaluate the effect of periodontal therapy on the risk for CV/CV disease is a major undertaking, and is currently being planned by the National Institute of Dental and Craniofacial Research.

PRETERM BIRTH AND LOW BIRTHWEIGHT

In 1996, Offenbacher et al identified a relationship between periodontitis and preterm low birthweight for first and all pregnancies.¹⁰ Subsequently, these findings have been supported by other investigators.^11,12 The cause of this link is believed to be the action of bloodborne oral bacteria or increases in blood levels of inflammatory mediators induced by oral infection on the pregnant uterus, which causes early delivery. Given the short duration of pregnancy relative to the decades long development of CV/CV disease, studying the effect of periodontal therapy on birth outcomes offers a way to verify the association and to identify a cost-effective approach to reducing this frequent and often devastating complication of pregnancy.

Preliminary studies have demonstrated that periodontal therapy can reduce the occurrence of preterm low birth weight. A study was conducted on 400 pregnant women with periodontal disease who received prenatal care in Santiago, Chile.¹³ Women were randomly assigned to either an experimental group that received periodontal treatment before 28 weeks of gestation or to a control group that received periodontal treatment after delivery. Known risk factors were obtained from patient medical records and interviews. The incidence of preterm low birth weight in the treatment group was 1.84% and 10.11% in the control group. Analysis showed that periodontal disease was the strongest factor related to preterm low birth weight. Other factors significantly associated with such deliveries were previous preterm low birth weight, less than six prenatal visits, and maternal weight gain. The researchers concluded that periodontal disease appears to be an independent risk factor for preterm low birth weight and that periodontal therapy significantly reduces the rates of preterm low birth weight in this population of women.

A study by Jeffcoat et al examined the effect of different periodontal therapies on the risk of preterm low birth weight.¹⁴ A total of 366 women with periodontitis between 21 and 25 weeks of pregnancy were assigned to one of three treatments: a dental prophylaxis, scaling and root planing, and scaling and root planing plus the antibiotic metronidazole. The groups were matched for other important variables related to risk for preterm birth including cigarette smoking, history of previous preterm birth, and bacterial vaginosis. Another group of 723 women served as an untreated control. The results indicated that preterm low birth weight (less than 35 weeks of gestation) occurred in 6.3% of the untreated group, 4.9% of the group receiving only a prophylaxis, 3.7% in the group receiving scaling and root planing and metronidazole, and 0.8% in the group receiving only scaling and root planing.

These data provide additional preliminary evidence that mechanical periodontal therapy alone can dramatically reduce preterm low birth weight in pregnant women with periodontitis.

DIABETES

Diabetes mellitus is a metabolic disease characterized by elevated levels of glucose in the blood. These elevated glucose levels are due to a lack of the hormone insulin (Type 1) or a reduction in the sensitivity of the receptors for insulin on cell surfaces (Type 2). The consequence of the elevated levels of glucose in the blood is a disruption in the body’s metabolic state, which can have serious adverse effects including increasing the inflammatory response in affected tissues.¹⁵

There are five classic complications of diabetes mellitus including: retinopathy (a variety of pathologic retinal changes that can lead to blindness) and nephropathy (structural and functional abnormalities that can cause end-stage renal disease)—both are microvascular complications; macrovascular complications like CV/CV disease; neuropathy; and poor wound healing.

Diabetes also plays an important role in the severity and rate of progression of perio-dontitis. Over the past two decades, overwhelming evidence has indicated that diabetes mellitus is a risk factor for periodontitis.¹⁶ The overall relative risk is in the two to three fold range, and diabetes can be considered the most important systemic risk factor for periodontitis (smoking, another important risk factor, is an environmental modifier). In 1993, periodontitis was proposed as the sixth complication of diabetes.¹⁷ Other oral manifestations of diabetes mellitus may include increased caries rate, reduced salivary flow, and oral candidiasis. However, these have not yet been conclusively proven.

With diabetic patients, the focus is on the effect of periodontitis on metabolic control and, consequently, the chances of developing other important systemic complications. Some indirect evidence for such an effect arises from two longitudinal studies where severe periodontitis in diabetic patients at baseline was shown to be associated with poor metabolic control,¹⁸ increased presence of proteinuria (excess serum proteins in the urine), and cardiovascular complications at follow-up.¹⁹

More direct evidence comes from treatment studies. For example, Grossi et al²⁰ demonstrated that scaling and root planing combined with systemic antibiotics reduced glycocylated hemoglobin (a measure of long term glucose control) in patients with diabetes mellitus. Evaluation was at baseline and then 3 and 6 months after therapy. While all groups demonstrated improvements in clinical measures of periodontal disease, the three groups that received local debridement and systemic doxycycline demonstrated a significant reduction in glycocylated hemoglobin at 3 months that rebounded at 6 months. In fact, a careful review of studies that examined the effect of periodontal therapy on glycemic control has identified systemic antibiotics as an important component of therapy when improved metabolic control was achieved.¹⁶

RESPIRATORY DISEASE

Perhaps the most direct association between periodontal infection and systemic disease is seen between periodontitis and respiratory diseases. Specifically, periodontal infection and respiratory pathogens in plaque have been linked to an increased risk for aspiration pneumonia and chronic obstructive pulmonary disease (COPD).²¹ Pulmonary pathogens have also been identified in subgingival plaque, particularly in infirmed patients.²²

Of greatest significance is a recent report that examined the effect of routine oral health care on the occurrence of fever and fatal aspiration pneumonia in nursing home residents.²³ Two groups were established—one received mechanical plaque removal and cleaning of the mucosal surfaces and dentures on a weekly basis (77 patients) while group two (64 patients) received routine care consisting of sponge brush cleaning and debris removal from dentures. The study was conducted over a 24-week period. Group one demonstrated a significantly reduced occurrence of fevers and fatal aspiration pneumonia as compared to group two.

As the population ages, more people will be living in nursing homes. If these findings can be extended to other groups of elderly, the importance of providing adequate oral health care services for older people will be integral to quality of life and reducing morbidity and mortality.

TREATMENT RECOMMENDATIONS

The evaluation of patients in the dental office begins with defining the reason for the visit and a review of the medical history, including medications currently used by the patient. Before periodontal disease was identified as a risk factor for certain systemic diseases, the medical history was used to determine if a patient could tolerate treatment or if a medical condition might account for an oral finding or the progression of an oral disease. Now, the emergence of periodontal medicine adds another consideration of the patient’s general health to treatment decisions in the dental office.

With this knowledge, new dental treatment plans for patients with certain systemic disorders or conditions like diabetes and pregnancy; those at risk for systemic disease; and those with a history of systemic conditions must be developed. Definitive recommendations can only be made after large scale studies are completed on the effects of periodontal treatment on specific systemic disease outcomes. Nevertheless, the American Academy of Periodontology (AAP) has taken the first step toward developing clinical guidelines.^24-26 The guidelines advise:

1. CV/CV disease. There is a statistically significant association between periodontal disease/infections and the risk for CV/CV disease. Currently, there is no evidence to indicate that periodontal therapy reduces the risk of CV/CV disease. However, suggesting that periodontal therapy may prevent the onset and delay the progression of CV/CV disease is plausible.²⁴
2. Preterm birth. There is a relationship between periodontal disease/infection and the risk for adverse pregnancy outcomes, including preterm birth. Causality has not been established. The association of adverse obstetrical outcomes and periodontal disease appears to also differ by ethnicity, with African Americans demonstrating a more pronounced effect. There is limited evidence indicating that mechanical periodontal therapy can reduce the occurrence of adverse obstetrical outcomes including preterm birth. Since periodontal therapy is associated with few adverse side effects, such treatment may be warranted. Treatment is recommended during the second trimester.²⁵
3. Diabetes mellitus. Diabetic patients should be evaluated for periodontal disease. In patients with periodontitis and diabetes mellitus, there is limited evidence that treating periodontal disease will improve metabolic control. Patients who seem to benefit the most are those with poorly controlled diabetes and severe periodontal disease. Treatment effects have been noted with mechanical debridement and systemic antibiotics.
4. Respiratory disease. There is an association of respiratory disease (nosocomial pneumonia) and periodontal disease. The incidence of nosocomial pneumonia in institutionalized individuals (patients in intensive care units, nursing home residents) may be reduced by good oral hygiene measures (mechanical plaque removal and application of topical chemotherapeutic agents). However, insufficient evidence exists to define a relationship between COPD and periodontal disease.²⁶

CONCLUSIONS

The discipline of periodontal medicine has raised some important new issues associated with treating patients in the dental office. Dental care must consider the impact of periodontal infection on systemic health. As oral disease-systemic disease linkages are further defined, the treatment of oral disease will be considered a requirement of complete disease management. The failure to notify a patient of treatment needs or a patient’s refusal to begin treatment will carry potentially important consequences for both the patient and the provider. Conversely, these relationships need to be presented to patients with an appropriate balance. The presence of periodontitis does not mean that a person will suffer a myocardial infarction or stroke. Rather, these systemic disorders are considered as complex diseases with multiple risk factors contributing to the patient’s overall or total risk. Patients can be told that oral health benefits will be gained from the necessary treatment and that those benefits may extend to reducing the risk for certain systemic diseases.

These findings have important implications for members of the professional dental team. They will influence the education of dentists and dental hygienists and how they interact with other members of the health care profession and their patients. These are exciting times and the concept of periodontal medicine may help define the future of dental practice..

REFERENCES

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From Dimensions of Dental Hygiene. April 2004;2(4):10-14.