Comparison of Streptococcus mutans biofilm formation, acidogenicity, and buffering capacity among human breast milk, plain packaged bovine milk, sweetened bovine milk, and infant formula: An in vitro study

Context: Human milk provides nutrients for newborns, while breastfeeding is preferred, formula feeding can also provide necessary nutrition and after weaning, individuals of all ages frequently drink bovine milk. Bovine and human milk contain lactose as a carbohydrate source, and infant milk formulas are also designed the same. However, lactose is fermentable by Streptococcus mutans, much like sucrose but to a lower extent.

Aim: This study aims to compare the S. mutans biofilm formation, acidogenicity and buffering capacity among human milk, plain packaged bovine milk (PBM), sweetened PBM, and infant formula (IF).

Settings and design: Microbiological assays, experiments on biofilm formation, acidogenicity and buffering capacity were conducted six times.

Subjects and methods: Ten distinct solutions were used: Plain PBM, sweetened bovine milk (SBM), IF, human breast milk (HBM), brain-heart infusion (BHI) with added 10% sucrose (BHI), and five duplicate solutions containing S. mutans culture. Biofilm formation - Biofilm development was evaluated on 96-polystyrene flat bottom plates. Biofilm acidogenicity - pH of the biofilms was determined by dipping in pH meter. Buffering capacity -0.01 M hydrochloric acid was added to every sample until pH reduction of two units was achieved.

Statistical analysis used: One-way ANOVA test, Tukey's post hoc test, independent Student's t-test were performed. The level of significance was set at P < 0.05.

Results: SBM had highest optical density (OD) value and HBM least. PBM had the highest pH and SBM least. PBM had highest B value (Buffering) and HBM least.

Conclusion: Cariogenicity of both HBM and PBM were shown to be just marginal although differing from sucrose.