Biofilms consist of bacterial cells surrounded by a matrix of extracellular polymeric substance (EPS), which protects the colony from many countermeasures, including antibiotic treatments. Growth and formation of bacterial biofilms are affected by nutrients available in the environment. In the oral cavity, the presence of sucrose affects the growth of Streptococcus mutans that produce acids that erode enamel and form dental caries. Biofilm formation on dental implants commonly leads to severe infections and can restrict osseointegration necessary for the implant to be successful. This work determines the effect of sucrose concentration on biofilm EPS formation and adhesion of Streptococcus mutans, a common oral colonizer, to titanium substrates simulating common dental implants. Biofilm formation and profiles are visualized at high magnification with scanning electron microscopy (SEM). Large mounds and complex structures consisting of bacterial cells and EPS can be seen in biofilms at sucrose concentrations that are favorable for biofilm growth. The laser spallation technique is used to apply stress wave loading to the biofilm, causing the biofilm to delaminate at a critical tensile stress threshold. The critical tensile stress threshold is the adhesion strength. Because laser spallation applies the stress loading to the rear of the substrate, bulk adhesion properties of the biofilm can be determined despite the heterogenous composition and low cohesion strength of the biofilm. Statistical analysis reveals that adhesion strength of biofilms initially increase with increasing sucrose concentration and then decrease as sucrose concentration continues to increase. The adhesion strength of bacterial biofilms to the substrate in this study is compared to the adhesion of osteoblast-like cells to the same substrates published previously. When sucrose is present in the biofilm growth environment, S. mutans adhesion is higher than that of the osteoblast-like cells. Results of this study suggest sucrose-mediated S. mutans biofilms may outcompete osteoblasts in terms of adhesion during osseointegration, which could explain higher rates of peri-implant disease associated with high sugar diets. Further studies demonstrating adhesion differentials between biofilms and cells including co-cultures are needed and motivated by the present work.
Bibliographical noteFunding Information:
This material is based upon work supported by the National Science Foundation CAREER Award grant number 2045853 and National Aeronautics and Space Administration grant number 80NSSC20M0251 . We gratefully acknowledge NIH funding under grant numbers P20GM130456 , P20GM103436 and R03DE029547 for completion of these experiments. This work is also made possible by the University of Kentucky University Research Postdoctoral Fellowship (L.W.), as well as the University of Kentucky College of Engineering through the Engineering Summer Undergraduate Research Fellowship (T.B.). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.
The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Martha Grady reports financial support was provided by National Institutes of Health . Martha Grady reports financial support was provided by National Science Foundation . Martha Grady reports financial support was provided by National Aeronautics and Space Administration .
© 2023 The Authors
- Dental implants
- Laser spallation
- Scanning electron microscopy
- Streptococcus mutans
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology
- Molecular Biology
- Cell Biology