Date of Award


Document Type


Degree Name

Master of Science (MS)


College of Science and Mathematics



Thesis Sponsor/Dissertation Chair/Project Chair

Lee H. Lee

Committee Member

Sandra D. Adams

Committee Member

Ann Marie DiLorenzo


An often overlooked disease, dental caries, or cavities, is one of the most prevalent infectious diseases across the globe. Streptococcus mutans (S. mutans) is the main etiological bacteria present in the oral cavity that leads to dental caries. All of the S. mutans in the oral cavity try to pool together to form an intelligent biofilm that adheres to the surfaces of teeth. S. mutans thrive on the sugary foods we eat and release acid by products that aid in the wearing away of the teeth’s enamel. As this enamel begins to wear away, the decaying process begins and cavities are formed.

A popular drink among many cultures, green tea contains polyphenols that have been previously reported to possess antioxidant, antimicrobial, antimutagenic, cancer preventing and anti-cariogenic properties. These green tea polyphenols have been studied in biofilm inhibition, but its role in cariogenic biofilm inhibition is not yet well known.

In this study, the stability of EGCG and EGCG-S were studied to determine its antimicrobial properties over a period of 5 months. Next, the effect of EGCG-S on S. mutans was examined through Colony Forming Units (CFU), Live/ Dead ® Assay and Scanning Electron Microscopy (SEM). Once the antimicrobial effect of EGCG-S was determined to be successful in inhibiting the growth of S. mutans, its effect to inhibit biofilm was studied through testing various sugar environments, Congo Red Assay and Crystal Violet Assay. The next objective of this study was to determine the possible synergistic effect of EGCG-S with common mouthwashes through disk diffusion, 96-well micro-titer plate assay, time course study, and Live/Dead ® Assay. Finally, The growth of S. mutans was monitored on three types of dental materials: Bruxzir®, PMMA, and EVA to see if treatment with EGCG-S inhibited its growth on these surfaces. This study suggests that EGCG-S is effective in reducing S. mutans growth, inhibiting its biofilm formation, enhances current mouthwashes antimicrobial properties, and has potential to reduce S. mutans growth on various dental materials.

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