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

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

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

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

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

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

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

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.

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

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 50- 60 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.

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

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.

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

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

Growth Curve for Streptococcus Mutans in Breast Milk

Growth Curve for Streptococcus Mutans in Infant Formula

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.

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

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.

References What’s in Breast Milk?. November 2011. American Pregnancy Association. Web. 30 December 2011. Perlstein, David. Infant Formulas: Which is better, breastfeeding or formula- feeding?. Web. 17 January 2012. http://www.medicinenet.com/infant_formulas/article.htm Enfamil PREMIUM Infant. 6 October 2011. Enfamil. Web. 15 January 2012. Bassett, Andrew. Streptococcus Mutans. 2006. Missouri S&T. Web. 30 January 2012. http://web.mst.edu/~microbio/bio221_2006/S_mutans.htm 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 2011. http://www.brianpalmerdds.com/bfeed_caries.html