Defense Date


Document Type


Degree Name

Master of Science


Pediatric Dentistry

First Advisor

Dr. Arthur Mourino


Purpose: The purpose of this study was to correlate the presence of Streptococcus mutans and Streptococcus sobrinus with the incidence of dental caries in children as detected by the polymerase chain reaction (PCR).Methods: Subjects between the ages 2 to 16 years of age were used in this study. After the subjects received a dental examination, dental plaque samples were collected by rubbing a toothpick on the buccal surface of the most posterior tooth in each quadrant of the mouth. Children were grouped into low, moderate, and high caries risk categories by two different Caries Risk Assessment Tools (CAT 1 and CAT 2). PCR was used to amplify the dextranase (Dex) gene of S. mutans and S. sobrinus. Dextranase is an enzyme that hydrolyses glucans in a plaque matrix and is believed to be involved in the pathogenesis of dental caries. Identification of the amplified Dex gene sequences was made by gel electrophoresis which in turn was used to determine the presence of S. mutans and S. sobrinus.Results: S. mutans was detected in 57% of patients (65/115), S. sobrinus was detected in 10% of patients (12/115) and both organisms were present in 9% of patients (10/115). According to CAT 1, the incidence of S. mutans was 64.6%, 9.2%, and 26.2% in low, moderate, and high caries risk, respectively. The incidence of S. sobrinus was 66.6%, 16.7%, and 16.7% in low, moderate, and high caries risk, respectively. Conclusion: Presence of S. mutans and/or S. sobrinus as evaluated in this study had no direct correlation with caries risk level in children.


© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

June 2008