1. Effects of Breast Milk and Formula on Dental Plaque Formation
Mia Fratto
Freshman
Oakland Catholic High School
1st Year in PJAS

2. Breast Milk Original Mammalian infant nutrition
Antibodies, living cells, enzymes and hormones make breast milk ideal because they have helpful benefits that cannot be added to infant formula
Reduces health problems such as diabetes, obesity and asthma
Considered a form of bonding for a mother and a child

3. Composition of Breast Milk
Made up of approximately 60% whey and 40% casein
Contains lactoferrin, secretory IgA, lysozyme, and bifidus factor
Contains the fats needed to create the long fatty acid chains which are needed for brain, retina and nervous system development
Contains lactose which helps decrease the amount of unhealthy bacteria in the stomach
Casein

4. Infant Formula Invented in the early 90’s
Became popular because typically mothers return to work very soon after giving birth and found it difficult to feed their babies
Gets other family member involved in intimate aspects of the baby’s care
Difficult for babies to digest because of the large content of casein

5. Previous Studies Research suggests breast milk is not cariogenic
IgA has the potential to retard streptococcal growth
Lactoferrin can kill off S. mutans

6. Streptococcus Mutan Gram positive bacteria
Found mostly in between and on the biting surface of teeth
Main component of plaque

7. Purpose
To determine what effect breast milk and infant formula have on the growth of Streptococcus mutans

8. Hypotheses
Null hypothesis: The growth of S. mutan will not be significantly different between the breast milk and infant formula.
Alternative hypothesis: Breast milk will have significantly less growth of S. mutan than infant formula.

9. Materials LB Soy Agar Plates Streptococcus Mutan
Sterile Dilution Fluid (SDF)
Sterile Test Tube
Sterile spreader bars
Incubator
Ethanol
Bunsen Burner
Vortex
Enfamil Infant Formula (concentrated liquid)
Breast Milk
Micropipettes
Klett Spectrometer
Turntable
Labeling Tape
Micro racks
Micro tubes

10. Procedures S. mutan was grown overnight in sterile LB media.
A sample of the overnight culture was added to fresh media in sterile sidearm flask.
The culture was placed in an incubator (37°C) until a density of Klett spectrophotometer units was reached. This represents a cell density of approximately 108 cells/mL.
The culture was diluted in sterile dilution fluid (SDF) to a concentration of approximately 105 cells/mL.
The breast milk and infant formula were mixed with SDF and cell suspensions to create the desired 10% experimental concentration.

11. Table of Concentrations
Control
Formula
Milk
Microbe
0.1 mL
SDF
8.9 mL
Variable
1.0 mL
Total
10 mL

12. Procedures 6. The solutions were vortexed to evenly suspend the cells.
100 µL aliquots were removed from the tubes and spread on LB plates at the following exposure times: 0, 30, 60, and 90 minutes.
The plates were incubated at 37°C for 24 hours.
The resulting colonies were counted visually. Each colony was assumed to have arisen from one cell.

13. Dunnett’s Test: Breast Milk
T-Critical = 2.57
Time
T-Value
Significant?
0 Minutes
5.07
Yes
30 Minutes
0.6 No
60 Minutes
0.8
90 Minutes
0.22

14. Dunnett’s Test: Infant Formula
T-Critical = 2.57
Time
T-Value
Significant?
0 Minutes
0.53 No
30 Minutes
0.14
60 Minutes
0.13
90 Minutes
2.58
Yes

15. Growth Curve for Streptococcus Mutans in Breast Milk

16. Growth Curve for Streptococcus Mutans in Infant Formula

17. Conclusion
The null hypothesis that the growth of S. mutan will not be significantly different between the breast milk and infant formula was rejected for the 0 minutes of breast milk and 90 minutes for infant formula.
The null hypothesis could not be rejected for 30, 60 and 90 minutes of breast milk and for 0, 30 and 60 minutes of infant formula.
The results and the statistical analysis indicate that the 0 minutes of breast milk and the 90 minutes of infant formula did adversely affect S. mutan growth.

18. Extensions
More trials to create a better basis for evaluating the results
Testing on real extracted human teeth in addition to the plates
Using sugar water as a variable
Using a different type of infant formula

19. Limitations Testing was not done directly on teeth.
The balance of the diet was not taken into account.
Some cells could have had longer or shorter exposure time.
The breast milk was not sterile filtered.
The plating was not perfectly synchronized.

20. References
What’s in Breast Milk?. November American Pregnancy Association. Web. 30 December 2011.
Perlstein, David. Infant Formulas: Which is better, breastfeeding or formula- feeding?. Web. 17 January 2012.
Enfamil PREMIUM Infant. 6 October Enfamil. Web. 15 January 2012.
Bassett, Andrew. Streptococcus Mutans Missouri S&T. Web. 30 January
Erickson, Pamela R. and Mazhari, Elham. “Investigation of the role of human breast milk in caries development.” Pediatric Dentistry 21.2 (1999). Print.
Palmer, Brian. Breastfeeding and Infant Caries: No Connection. Web. 26 November