Diabetes and Oral Health: What’s Their Relationship?

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A healthy mouth is essential for healthy living. The mouth is where digestion begins when chewing mixes food with saliva. A healthy mouth is also important for communication and social interaction, and overall personal appearance is dramatically affected by one’s smile. Everyone needs to pay attention to oral health. As emphasized by former Surgeon General C. Everett Koop, a person is not truly healthy unless he also has oral health. This is particularly true for people living with diabetes.

The potential complications of diabetes are well known to most people with the condition. These include retinopathy (diabetic eye disease), potentially leading to impaired vision and blindness; nephropathy (kidney disease), possibly leading to the need for dialysis or kidney transplantation; heart attacks and strokes; nerve and sensory disorders; and poor wound healing, often evidenced by ankle and foot ulcers.


In addition, a number of oral disorders are associated with diabetes. It is important that people with diabetes, their health-care providers, and any caregivers understand the importance of oral health and, if problems occur, arrange for appropriate care. Especially important is preventive oral health care, which involves personal oral hygiene practices and regular visits to the dentist.

Preventive care

Preventive oral health care is an essential part of maintaining a healthy mouth, including the teeth, the gums, and the mucosal surfaces in the mouth (which include the tongue, the palate, and the insides of the cheeks and lips). This begins with effective oral hygiene, including brushing the teeth twice daily. The goal of toothbrushing is removal of dental plaque and food particles that adhere to the teeth. Dental plaque is the soft material that coats the surfaces of the teeth, including the area below the gum line (the gingival margin). Plaque is a biofilm, composed of many different species of bacteria embedded in a matrix of complex sugars. The types of bacteria found in plaque in a healthy mouth differ from those found in a mouth affected by dental disease. A dental cleaning provided by a dentist or dental hygienist removes the soft plaque as well as its calcified form, known as tarter (also called calculus).

A soft-bristle, manual toothbrush is the first option for most people; using such a brush helps avoid damaging the teeth and gums. Electric or automatic toothbrushes are also available. These devices have an oscillating or rotating head and can be useful to people with limited manual dexterity (such as those who have experienced a stroke or have arthritis affecting their hands) who are unable to effectively use a manual brush.

With either type of brush, toothpaste should be used; fluoridated toothpaste is best. Fluoride has antimicrobial properties and can strengthen tooth enamel by becoming incorporated into its crystalline structure. Approximately half an inch of paste should be placed on the brush. Teeth should be brushed for about two minutes, with equal time devoted to the teeth in the upper jaw and lower jaw. Both the outer surfaces and inner surfaces of the teeth should be cleaned.

Dental floss should also be used daily to remove plaque between the teeth. Waxed floss is best to facilitate plaque removal between tight tooth contacts, areas that cannot be reached through toothbrushing.

Additional products can also be helpful, depending on conditions in the mouth. Mouth rinses can be used to reduce bad breath; some rinses also have an antiplaque effect. In addition to dental floss, several different between-the-teeth (interproximal) cleaning devices are available, which can be used to remove plaque from tooth surfaces when there is space between the teeth. These devices include small brushes, wide-diameter dental floss, and interproximal picks and wedges.

The tendency to accumulate dental plaque is an inherent trait – that is, some individuals are heavy plaque formers, while others are not. In all cases, proper oral hygiene and regular dental care are essential to reducing plaque accumulation. Teeth that are fractured, have broken or chipped dental restorations, or have large cavities are places where plaque will tend to accumulate. A combination of personal care and professional care is the key to a lifetime of good oral health.

Gum disease

A number of oral and dental diseases and disorders have been associated with diabetes. The most commonly seen oral complication of diabetes is periodontal disease (gum disease). Periodontal disease can be broadly classified as gingivitis or periodontitis. Gingivitis is inflammation of the soft tissues surrounding the teeth. The alveolar bone, to which the teeth are attached, is unaffected by gingivitis.

Periodontitis is a group of disorders in which the inflammation involves both the soft tissues and the alveolar bone. In periodontitis, the alveolar bone is resorbed – that is, it begins to dissolve at the margin where the tooth is embedded in bone. The result is that the cuff of soft tissue deepens, with the formation of what is referred to as a “pocket.” These pockets are difficult to clean, so bacteria can accumulate and proliferate, which elicits an even greater inflammatory response. The inflammatory cells that are part of this response produce biologically active molecules (enzymes and cytokines) that have many effects, including stimulation of the cells that resorb bone (osteoclasts). This leads to irregular bone architecture that further complicates cleaning.

Sometimes a pus-filled swelling of the gum occurs, known as a periodontal abscess. Teeth can become loose and may eventually need to be extracted; one sign of this is that the gum recedes and the teeth appear longer. It is important to emphasize that periodontitis can be prevented or its onset delayed. Once present, periodontitis can generally be treated.

There is very strong evidence that the extent and severity of periodontitis are greater in people with diabetes than in those without diabetes. Periodontal complications of diabetes were first reported more than 150 years ago, including abscess formation and development of intense inflammation where the tooth and soft tissue meet. Some of the most convincing data on the relationship between diabetes and periodontal disease come from the Pima Indians in Arizona. These Native Americans have the highest incidence of Type 2 diabetes in the world, and studies of this group have demonstrated that periodontitis is more common and more severe among people with diabetes. This was found to be true for all age groups.

The relationship between diabetes and periodontal disease appears to be bidirectional – that is, in addition to the increased occurrence of periodontal disease among people with diabetes, there is evidence that untreated periodontal disease in people with diabetes can negatively affect blood glucose control and, ultimately, health outcomes. There are two lines of evidence to support this conclusion. First, a number of studies have examined the effect of treating existing periodontal disease on blood glucose control in people with diabetes, measuring either fasting plasma glucose or glycosylated hemoglobin (HbA1c, a measure of long-term blood glucose control). Conservative periodontal therapy was found to reduce HbA1c by 0.4%, which lasted for three months after therapy. This occurred in the absence of any medical treatment.

Other studies suggest that if periodontal disease is present in people with diabetes, over time, health outcomes are worse. Another study of the Pima Indians revealed that periodontal disease increases the risk of death from heart or kidney disease. The probability of death from these causes was proportional to the severity of periodontal disease. In this same population, the presence of periodontitis was predictive of nephropathy and end-stage renal (kidney) disease, again depending on severity.

These findings are intriguing but should be interpreted cautiously, because cause and effect could not be established. Nevertheless, these data clearly support the idea that a healthy mouth is essential for people living with diabetes.

Dental cavities

Gum disease is not the only oral problem associated with diabetes. Dental cavities (also called caries) are the result of certain bacteria that accumulate on the tooth surface as part of the plaque. These bacteria (Streptococcus mutans, Lactobacillus species) metabolize sugar and other fermentable carbohydrates, producing lactic acid as a by-product. This acid can dissolve the mineral component of teeth (hydroxapatite). The dissolution results in a cavity, which can be sensitive to changes in temperature when the demineralization extends into the deep layers of the tooth.

The outer covering of the part of the tooth that is visible (the crown) is enamel; cavities become painful when the underlying dentin is affected. If the cavity progresses into the pulp, the inner chamber at the center of each tooth that contains nerves and blood vessels, the pain can become very intense. This “toothache” is often accompanied by facial swelling, as the infection spreads into the bone and soft tissue surrounding the tooth. In addition, when receding gums are present, a root cavity can develop. This is decay that develops mostly in older individuals if the root of the tooth is exposed. The root is covered with a softer mineralized tissue known as cementum. The cementum layer is not as dense as enamel and therefore very susceptible to the effects of acid.

The association between diabetes and tooth decay is not clear, and both higher and lower rates of cavities have been reported in people with diabetes compared with the general population. The reasons for these conflicting findings may relate to diet: a high carbohydrate intake can contribute to the development of dental cavities. Conversely, a low carbohydrate intake, which describes the dietary habits of many people with diabetes, results in a lower risk of cavities.

Recent studies involving older adults may help clarify this situation. Saliva not only helps begin the digestive process when food is in the mouth, but is also very important in buffering the acid produced by bacteria that metabolize fermentable carbohydrates. Some people with poorly controlled diabetes have reduced salivary flow (called xerostomia). Furthermore, a side effect of many medicines is a reduction in saliva. This change in the flow of saliva tends to occur in older individuals and appears to be more pronounced in people with diabetes.

People with reduced salivary flow are particularly susceptible to root cavities. Root cavities can be prevented or minimized by practicing good oral hygiene. This means removing plaque from the exposed root surfaces through brushing, as well as getting regular professional cleanings. Using a fluoride-containing toothpaste or receiving professional fluoride treatments may also help. Some severe cases may require dental restorations to cover the exposed and susceptible root surfaces.

Other oral problems

Another recognized oral complication of diabetes is burning mouth syndrome (BMS). BMS is not unique to diabetes and can have a variety of other causes, including the use of a number of medicines as well as certain hormonal abnormalities that occur predominately in women. In diabetes, BMS is often associated with a reduction in the production of saliva and a secondary yeast (Candida) infection. In BMS, the lining of the mouth is irritated, and the mucosal surfaces appear red. If saliva production is reduced, the mouth will also feel dry, and chewing food or even talking may become difficult.

Yeast infection can take a variety of forms and may contribute to the redness of the mucosa, or it may appear as white patches. It may be possible to scrape these yeast accumulations off the mucosal surfaces of the mouth. A visit to the dentist, and a comprehensive evaluation that includes an assessment of blood glucose control, are needed in any case of BMS.

Other, less common oral complications of diabetes have been reported. One example is diabetic sialosis, also called benign parotid hypertrophy. The parotid glands are the largest of the salivary glands, which produce saliva. They are located toward the outside of the face, just below the ears, extending down toward the angle of the lower jaw. In diabetic sialosis, the glands become enlarged, and swelling appears on the outsides of the cheeks. This condition, which results from an increase in the size of the cells in the gland, is benign. Its most significant consequence is the altered appearance of affected individuals.

Final thoughts

Oral health care should be considered part of the essential care of people with diabetes. This should begin with a thorough oral examination when a person is first diagnosed with diabetes, regardless of age. Regular dental examinations to look for changes in oral health are recommended for everyone, but they are particularly important for people with diabetes.

Studies have shown that people with diabetes do not utilize dental services as often as people without diabetes. The reasons for this situation are complex, but it may be due to the enormous amount of time people with diabetes spend addressing their health-care needs – leaving little time for health concerns that have not been emphasized by their health-care team. However, neglect of oral health can have a tremendous negative impact on people with diabetes, affecting both health outcomes and quality of life. Once oral health is established, however, routine and relatively simple preventive measures can be very effective in maintaining a healthy mouth for a lifetime.

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