- Brian L. Mealey, DDS, MS
Oral conditions that are seen in individuals with diabetes may include burning mouth, altered wound healing, and an increased incidence of infection. Enlargement of the parotid glands and xerostomia can occur; both are conditions that may be related to the metabolic control of the diabetic state. Medications that diabetic patients often take for related or unrelated systemic conditions may have significant xero-stomic effects. Thus, the xerostomia seen in individuals with diabetes may result more from medications than from the diabetic condition itself.
Neuropathy of the autonomic system can also cause changes in salivary secretion since salivary flow is controlled by the sympathetic and parasympathetic pathways. Dry mucosal surfaces are easily irritated and are associated with "burning mouth" syndrome; they also provide a favorable environment for the growth of fungal organisms. Some studies have shown an increased incidence of oral candidiasis in patients with diabetes whereas other studies have not.
The effect of diabetes on the dental caries rate is unclear. Some studies have demonstrated increased caries in people with diabetes, which has been associated with xerostomia or increased gingival crevicular fluid glucose levels. Other studies have shown similar or decreased caries rates in people with diabetes. Since most diabetic individuals limit their intake of fermentable carbohydrates, the less cariogenic diet may limit caries incidence. In recent studies of type 2 diabetic patients and nondiabetic control subjects, no differences were seen in salivary flow rates, organic constituents of saliva, salivary counts of acidogenic bacteria, salivary counts of fungal organisms, or coronal and root caries rates. These findings suggest that diabetic individuals as a group are similar to nondiabetic people in regard to these oral conditions.
Effects of Periodontal Infection on Glycemic Control
Not only does diabetes affect the periodontium, but evidence also suggests that periodontal infection may adversely affect glycemic control of diabetes. Diabetic subjects with severe periodontal disease often have a worsening of glycemic control over time, compared to diabetic subjects without periodontitis. Periodontal infection increased the risk of poor glycemic control by sixfold in one study. Periodontitis is also associated with an increased risk for other diabetic complications, such as nephropathy and macrovascular disease. In one study, 82% of diabetic patients with severe periodontitis had at least one major cardiovascular, cerebrovascular, or peripheral vascular event during the 1- to 11-year study period, compared to only 21% of diabetic subjects with little or no periodontal disease.
In diabetic patients with periodontitis, periodontal treatment may have beneficial effects on glycemic control. Several well-controlled studies of diabetic subjects with severe periodontal disease have shown improvements in glycemic control following a combination of mechanical debridement (scaling and root planing) and systemic doxycycline antibiotic therapy. Other studies in which patients received only mechanical therapy or in which the subject population already had good glycemic control prior to periodontal treatment showed no significant effect on glycemic control. The mechanisms by which adjunctive systemic antibiotics, when combined with subgingival mechanical debridement, may induce positive changes in glycemic control are presently unclear. Changes may result from more complete elimination of the subgingival pathogens in patients receiving antibiotics or from the suppression of collagenase production and AGE formation.