Michele Ravenel, DMD
Microbial Analysis of Dental Plaque Species in the Sea Island Gullah Population (Start date 7/1/07)
The purpose of this pilot study is to characterize the microbial flora associated with dental disease in the Gullah population using checkerboard DNA-DNA hybridization (Forsythe Institute). Information gained will illuminate potential oral pathogens unique to the Gullah population as well as generate protocols for the management of oral disease in this population. Data gathered in this pilot study will also allow a more advanced meta-genome analysis further illuminating the genetic influence on disease incidence and severity. Such meta-genome analysis has been supported in the past by NIDDS and can be used to perform extensive analysis of microbial populations.
Specific Aim 1: Microbial analysis of supra-gingival plaque species of Sea Island Gullahs with type 2 diabetes using checkerboard DNA-DNA hybridization
Hypothesis: The microbial supra-gingival plaque species of the Gullah type 2 diabetic will differ as compared to non-Gullah type 2 diabetics.
Background and Significance
Dental plaque is a biofilm containing over 500 microbial species. It is also the primary causative agent of dental caries. Dental caries is a common, chronic disease which if left untreated can result in pain, infection and tooth loss. Although the incidence of dental caries has decreased in the past three decades, minorities and low income Americans continue to suffer higher rates than non-minorities. Both the 1989-1994 and 1999-2002 NHIS Surveillance for Dental Caries, Dental Sealants, Retention, Edentulism, and Enamel Fluorosis (NHANES) noted disparities in dental caries across all age groups, among racial groups and in individuals with lower education and income3.
The Sea Island, Gullah speaking African Americans (Gullah), are considered to be direct descendants of native African peoples. Their ancestors were brought to the United States from the West African coastal region, ranging from present day Senegal, Gambia and Angola. They are considered the most genetically homogeneous African American population with only a 3.5% European Caucasian admixture. This genetic homogeneity makes them a unique population to study the genetic influence on disease.
In a soon to be published study assessing dental caries in Gullah type 2 diabetics, no association was found between glycemic control of diabetes and dental caries both with and without adjustment for smoking, BMI, age and sex. As expected the mean Decayed-Missing-Filled Tooth (DMFT) scores for the Gullah population was higher than that of the NHANES white population. However, the DMFT scores for the Gullah population was also higher (17.6±6.9) as compared to both the 1989 NHANES Blacks (12.43±0.14) and 1999 NHANES Blacks (11.07±0.018). Higher DMFT scores in the Gullah population as compared to the NHANES Black population suggests other factors in addition to income and access to care are involved in the pathogenesis of dental disease in the this population. One factor to consider is the difference in the oral microbial flora of the Gullah population. Similar studies of known oral pathogens have been conducted on the general population 9-14, but to date no such study on the Gullah population exists in the literature.
The purpose of this pilot study is to characterize the oral microbial species in the supra-gingival dental plaque of Gullah type 2 diabetics using checkerboard DNA-DNA hybridization (Forsythe Institute). A modified checkerboard panel developed to study the more gram positive cariogenic species will be used. The percent of individuals that have selected bacterial species present will be compared to similar studies of non-Gullah type 2 diabetics. Information gained will illuminate potential oral pathogens unique to the Gullah population as well as generate protocols for the management of dental disease in this population.