Brett Kim
| Brett Kim |
Brett Kim
Geelsu Hwang
Division of Restorative Dentistry, University of Pennsylvania, School of Dental Medicine
Introduction
Biofilms are dynamic, structured microbial communities responsible for the biofouling processes often seen in dental settings. These communities initiate through adhesion to a surface, and progressively mature into complexes that are difficult to kill and remove by mechanical debridement. Various factors may affect the adhesion efficacy of bacteria, including surface energy, topography, and surface stiffness. The goal of this study is to examine the adhesion properties of different oral bacterial species in single-species biofilm growth on varying surface stiffness.
Methods
Varying composition of Polydimethylsiloxane (PDMS)-crosslinker discs were created to simulate varying surface stiffness environments for biofilm-forming oral bacterial species. Each disc was inoculated for 4 hours in separate single species culture mediums consisting of either Candida albicans, Streptococcus mutans, and Streptococcus oralis. Following inoculation, sample groups were assessed for their adhered bacterial amounts. The amount of adhered bacterial colonies was subsequently assessed through mechanical debridement and sonication of the PDMS discs. Adhered colony samples were then grown on agar plates and allowed to grow for 2 days for quantification. The main biofilm analysis utilized for this experiment included the average number of bacterial colonies grown following agar plating for adhered samples. A statistical analysis was then conducted between the different bacterial species for adhered groups.
Results
Streptococcus mutans adhered groups showed much greater bacterial counts for softer PDMS disc surfaces for 20:1 and 40:1 compositions compared to stiffer 5:1 and 10:1 compositions (p>0.05). Candida albicans and Streptococcus oralis adhered groups showed similar differences of greater bacterial growth for softer PDMS discs when compared to stiffer discs.
Conclusion
The results of this study indicate the variable bacterial adhesion for different surface stiffnesses and possible favoring of softer surfaces across three oral bacterial species. Future studies could assess the impact of a multi-species biofilm assay on initial (4 hour) adhesion, or longer inoculation of oral bacteria (24 hour growth) in both single or multi-species assays.