Diabetes mellitus and periodontal disease are two relatively common chronic diseases in the US and are believed to be biologically linked 9,30,31
. Several systemic factors are associated with an increased incidence and severity of periodontal disease in patients with diabetes. Current evidence regarding the biologic link between diabetes and periodontal disease supports persistent hyperglycemia leading to exaggerated immuno-inflammatory response to the periodontal pathogenic bacterial challenge, resulting in more rapid and severe periodontal tissue destruction 32,33
. Polymorphonuclear leucocytes (PMN) are considered a first-line host defense mechanism in inflammatory processes. They are primary protective against pathogenic bacteria and play a role in periodontal wound healing. PMN function is impaired in patients with diabetes, reducing their ability to combat infections. An increase in prevalence and severity of periodontal disease in subjects with diabetes is due to reduced PMN chemotaxis, phagocytic defects, and depressed humoral response. Also in a hyperglycemic environment, numerous proteins undergo glycosylation to form advanced glycation end-products (AGE). AGE-mediated events are of primary importance in the pathogenesis of diabetes complications and may also contribute to tissue changes within the periodontium…34
Gullah Sea Islanders are a unique population with only 3.5% European gene admixture compared to 17.7% in African Americans living inland.19
The determination of the extent of European admixture is not only of great anthropological significance but may also shed light on why host responses differ, despite similar environmental and bacterial exposure. Several genetic polymorphisms have been associated with chronic severe periodontitis17,35,36
. The unique homogeneity of Gullah Sea Islanders makes this population especially attractive for studying the influence of genetics on periodontal disease expression.
Studies to investigate the association between periodontal disease and diabetes mellitus have been conducted using varying case definitions of periodontal disease, with individuals from different populations, age groups, and different types of diabetes, making true assessment of prevalence of periodontal disease in diabetes difficult.37
In Pima Indians, Emrich38
found that patients with diabetes had three times the risk of periodontitis compared to patients without diabetes. Lalla et al.39
provided additional evidence that diabetes is an important risk factor for oral disease among the low-income, underserved population of Northern Manhattan. Other studies have not found any difference in the prevalence of periodontal disease and diabetes.2,40
A recent meta analysis conducted to asses the association between diabetes and periodontal disease concluded that subjects with diabetes had a significantly higher severity, but no statistical difference in the percentage of sites affected by periodontal disease when compared to subjects without diabetes.41
We used case definitions of periodontal disease well described in the literature to characterize periodontal disease in our Gullah population with diabetes. Using the same case definition as our moderate periodontitis, Borrell et al.24
reported an overall prevalence of periodontal disease of 7.3% in the NHANES III42
data and 4.2% for the NHANES 1999–200043,44
data. African Americans had the highest prevalence of periodontitis, representing 11.4% and 6.8% for the NHANES III and NHANES 1999–2000 studies, respectively. Further, African Americans who reported no prior diagnosis of diabetes had prevalences of 10.6% (NHANES III) and 6.4% (NHANES 1999–2000). The corresponding prevalences for African Americans reporting a diagnosis of diabetes were 31.3% and 12.8%. Our finding of 70.6% prevalence of periodontal disease among Gullah African Americans with diabetes is significantly higher (p<0.001) than these national figures, even when compared to the rate among African Americans with diabetes. Our PD measurements were rounded down to the next whole decimal, unlike the NHANES protocol, which rounded up. Thus, we may be underreporting the prevalence of periodontal disease in this population.
In NHANES III and NHANES 1999–2000 among the Black subgroup, 31.7% and 25.7% were reported as current smokers, 13.1% and 13.4 % as former smokers and 55.2% and 60.9% as never smokers24
. In comparison, 14.9% of our subjects were current smokers, 14.9% former smokers and 70.2% reported to have never smoked. We classified subjects as smokers if they were currently smoking; past smokers if they had smoked in the previous 6 months, but were not smoking currently; and non-smokers. NHANES smoking status was derived from two questions in both surveys. “Do you smoke cigarettes now?” and “Have you smoked at least 100 cigarettes in your entire life?” Smoking status for NHANES was defined as current smokers (subjects who answered “Yes” to both questions), former (subjects who answered “No” to the first question and “Yes” to the second question), and never smokers (subjects who answered “No” to both question”. The difference in smoking classification should be taken in to account when interpreting our study data.
This study represents the first investigation in to the prevalence of periodontal disease in Gullah Africans-Americans. We found significantly higher periodontal disease prevalence in Gullah T2Ds compared to African Americans in the NHANES populations. Our study population, however, is limited to subjects with diabetes and those with well-controlled diabetes served as controls for the poorly controlled subjects. These subjects were predominantly of lower socioeconomic status with limited dental care access. Poor oral health care has traditionally been linked to lower socioeconomic status and may influence our results. Also, 74% of our subjects were women, and 61 % of the subjects were between the ages of 51–70 years. Enrollment of more men and/or younger subjects may change study results; every effort will be made to increase recruitment of these groups for future studies.
Mean total missing teeth (TMT) due to caries or periodontal disease per subject reported for NHANES 1988–1994 and 1999–2002 among dentate non-Hispanic black adults was 6.87 (se = 0.15) and 5.78 (se = 0.14), respectively 45
. In comparison, the mean TMT due to caries or periodontal disease of our 235 Gullah subjects with diabetes was significantly higher (p<0.01) at 8.3 (se = 0.42) (range of 0–25). Edentulous or subjects with less than 3 teeth were not included in our study, and the cause of missing teeth was recorded as attributable to decay (caries), trauma, periodontitis or other according to patient recall. We recognize that recall may be erroneous, as often the event occurred several years earlier. Our study results should be interpreted in light of the high number of missing teeth in our sample as compared to that reported in NHANES.
Our report suggests a high prevalence of periodontal disease in the Gullah African-American with diabetes living in South Carolina. Low socioeconomic status, presence of other systemic diseases, and a unique genetic background may increase susceptibility to periodontal disease, all of which warrant further investigation.