All ETDs from UAB

Advisory Committee Chair

Noel K Childers

Advisory Committee Members

Gary R Cutter

Stephen A Moser

Firoz Rahemtulla

John D Ruby

Document Type

Thesis

Date of Award

2010

Degree Name by School

Master of Science (MS) School of Dentistry

Abstract

Mutans streptococci (MS), Streptococcus mutans and Streptococcus sobrinus are associated with the initiation of dental caries in humans. Initially, a single S. mutans genotype has been shown to colonize primary molars soon after eruption. More genotypes can be acquired with age and further dental development. Current methods used to genotype isolates from an individual have not systematically determined the minimum number required to demonstrate an individual's genetic diversity. The purpose of this study was to determine the optimum number of oral isolates of MS (i.e., from plaque samples) to genotype in order to demonstrate diversity. This study also initiated a longitudinal study of S. mutans genotypes to determine diversity, commonality, and stability for primary and newly erupting permanent molars in a high caries risk population. The subjects included 5-6 year old children (index children) prior to eruption of at least one permanent molar and adults. Cultured MS positive isolates were verified by SYBR PCR. DNA was extracted for repetitive extragenic palindromic-polymerase chain reaction (rep-PCR) followed by Microfluidics-based DNA amplicon fractionation using an Agilent 2100 Bioanalyzer. Data analysis was performed with the DiversiLab software (v3.3) using the Pearson Correlation Coefficient method to create DNA fingerprints, dendrograms, and similarity matrices to interpret data. This study showed that 7 to 10 isolates were determined to be a practical number of isolates to collect per individual (i.e., up to 51 to 78% probability of identifying 4 genotypes when they exist). Nineteen children were found to have a total of 11 genotypes at baseline and at 6 month follow-up with a mean of 1.5 genotypes (diversity) per individual. The most common genotype was shared by six children, and seventeen among nineteen children shared at least one genotype with another child's pla-que (commonality). A predominant genotype from each individual (N = 19) at baseline was retained at the 6 month follow-up (stability = 100%). This study demonstrated the characteristics of diversity, commonality, and stability of S. mutans genotypes among a high caries risk children population in a 6 month longitudinal study. The method of highly automated rep-PCR with DNA chip assay is an efficient tool to characterize S. mutans genotypes and constructing a longitudinal database.

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Dentistry Commons

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