Transcript Slide 1

Inhibitory Effects of Mouthwashes on the Cavity-Causing (Cariogenic) Bacterium
Streptococcus mutans
Ryan Schell*, Tonya Tanner*, and Dr. Chad R. Sethman
Waynesburg University Department of Biology
†
70
Doubling Time (min)
A dental carie (cavity) is defined as damage to the tooth enamel caused
by certain bacterial metabolic processes. During the period of time between
brushings many layers of bacteria accumulate on the surface of teeth
forming what is called a bio-film. One of the early colonizers of this biofilm, Streptococcus mutans, is the bacterium responsible for the carious
nature of the bio-film. Anti-cavity mouthwashes are marketed as an
effective means of inhibiting the growth of bio-film forming bacteria and
thus preventing the formation of caries. The goal of our research is to
evaluate the efficiency of various commonly available mouthwashes at
inhibiting the growth of S. mutans. We first compared the growth of S.
mutans in various media by assessing maximum density and doubling time
using plots of optical density versus time. We found that Trypticase Soy
Broth (TSB) provided one of the quickest doubling times and the highest
maximum density. Using TSB as the growth medium, we found that the
growth rate of S. mutans is inhibited by Listerine® in a concentrationdependant manner.
Additionally, we plan to compare multiple
mouthwashes as well as multiple toothpastes for their effectiveness at
inhibiting S. mutans growth using this same methodology.
Doubling Times Vs. Max. Densities
80
Doubling Times
1.4
****
Max. Densities
1.2
60
50
***
1
***
****
0.8
40
†
††
†††
30
††
0.6
0.4
Max Density (Absorbance)
Abstract:
20
†††
10
0.2
0
0
TS
BHI
TYC
Figure 3: A spectrophotometer.
Figure 4: Streptococcus mutans.
Picture from David B. Fankhauser,
Ph.D. University of Cincinnati Clermont
College.
Gram stain. Courtesy of CDC/Dr. R
Facklam.
Conclusions:
S. mutans prefers Trypticase Soy Broth to the other various media
In TSB S.mutans has an average doubling time of 42.83 minutes
In 5% Listerine ® S. mutans has an average doubling time of 96.63 minutes
Trends show that the more Listerine® mouth wash that is added the slower the
bacteria grows yielding a greater doubling time
N
Figure 1:
Analysis of the doubling-time and maximum density of S.mutans grown in various media. Data
represent averages of five sample runs. Error bars represent standard deviation. ***p<0.05, ****p<0.01, † p<0.001,
†† p<0.05, ††† p<0.01.
Media Used:
160
Goals/Specific Aims:
Test various toothpastes using the same methodology.
Colgate Total®
Crest® (original)
Rembrandt®
Sensodyne®
Test various other believed remedies.
Hydrogen Peroxide
Baking Soda
Orange Juice
Salt Water
Determine weather the inhibitory effects are due to bacteristatic growth or if the
mouthwashes are bactericidal.
Doubling times in Listerine® mouthwash
140
Doubling time (minutes)
Tripticase Soy Broth (TS)
Brain Heart Infusion Broth (BHI)
Tryptone Yeast Cystine Broth (TYC)
Nutrient Broth (N)
Listerine® Mouthwash
Future Studies:
120
100
80
60
40
20
Find the most desired media for the growth of S. mutans.
Find a desired concentration of mouthwash that doubles the original doubling
time in TS Broth
Find a mouthwash at the desired concentration that inhibits the growth of
S.mutans the best.
Acknowledgements:
0
0%
0.10%
1%
3%
5%
V/V% Listerine ® added to 12.5ml of TS broth/S.mutans
10%
Figure 2: Analysis of the growth of S. mutans in TS broth with various concentrations of Listerine®.
represents an average of three sample runs.
Data
I would like to thank Dr. Chad Sethman for mentoring this project. I would
also like to thank the Waynesburg Universities Center for Research and
Economic Development for poster printing and financial support.