Date of Award


Document Type

Open Access Dissertation


Epidemiology and Biostatistics

First Advisor

Anwar T. Merchant


Periodontal disease is a low-grade chronic inflammation in the tissues surrounding the teeth caused by multiple, mostly gram-negative pathogens. It is associated with diabetes, obesity, and chronic inflammation. The specific roles that periodontal microorganism play in these conditions are not well-studied. Hereby, we explored how periodontal bacteria from sub gingival plaque clustered in youth with and without type 1 diabetes, and how such patterns related to body-mass-index percentile (BMI percentile), C-reactive protein (CRP) and adiponectin. Cross-sectional data were collected from 105 youth with type 1 diabetes and 71 without diabetes. Participants were between 12 and 19 years of age receiving care at the Barbara Davis Center in Colorado, 2009-2011. Counts of 41 oral-bacteria from sub gingival-plaque were obtained using DNA-DNA hybridization, and grouped using cluster-analysis. Standardized-mean counts of each organism were computed and summed to get microbial-scores per cluster. A subset (n=101, 54 with type 1 diabetes) underwent dental examinations at the University of Colorado, School of Dental Medicine clinic. Participants were 15-years old on average; 51% were female; 73% non-Hispanic white; 37% overweight; the average diabetes duration was 8 years. About 48% brushed their teeth twice/day; 12% flossed once/day; 47% visited a dentist in the past 6 months.

Bacterial clusters were identified and named after Socransky’s color-coded complexes as ‘blue-other’, ‘orange-blue’, ‘orange-red’, and ‘yellow-other’. Individuals with and without type 1 diabetes had similar microbial composition. Cases of type 1 diabetes ranking in the highest tertile of CRP were older, female, had higher Hemoglobin-A1c (HbA1c) and glucose levels, brushed their teeth at least twice a day but did not floss at all. Those in the highest tertile of adiponectin were similar. Gingival condition was similar across the tertiles of CRP and adiponectin. Cluster scores were not significantly different; however, overweight participants had qualitatively lower scores for clusters 2 and 3 than normal participants. Clusters of periodontal microorganisms were associated with CRP and adiponectin after accounting for potential confounders. The oral composition of microorganisms was similar among youth with and without type 1 diabetes. Normal and overweight youth with type 1 diabetes had similar profiles too. This may be due to young age of participants, relatively short type 1 diabetes duration, regular medical care, and low level of periodontal disease. CRP was positively-related to the ‘orange-blue’ cluster and adiponectin was negatively-related to the ‘Blue-Other ’ cluster.


© 2014, Georges Joseph Nahhas

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