Saudi Cultural Missions Theses & Dissertations
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Item Restricted Effects of Probiotic Lactobacilli on Streptococcus mutans: Implications for Early Childhood Caries(Saudi Digital Library, 2025-06) Al Turki, Walaa; Zhang, PingEffects of Probiotic Lactobacilli on Streptococcus mutans: Implications for Early Childhood Caries WALAA MOHIEDEN AL TURKI DENTISTRY ABSTRACT Purpose: Probiotic Lactobacillus species have been shown to have beneficial effects against early childhood caries (ECC) by inhibiting the growth of cariogenic bacteria. However, the acidogenicity of Lactobacillus spp. could have potential carcinogenic effect. The objective of this study was to investigate the effects of probiotic lactobacilli and cariogenic lactobacilli on the growth, biofilm formation, and acid production of Streptococcus mutans (S. mutans). Methods: Growth competition between probiotic L. rhamnosus GG (L-GG) or caries-associated L. rhamnosus M72-26 (L-M72) and S. mutans UA159 were assessed on Todd Hewitt Yeast (THY) agar plates and De Man-Rogosa-Sharpe (MRS) agar plates. Lactobacilli and S. mutans single- and dual-species biofilm formation in THY and MRS media containing 1% sucrose were evaluated via crystal violet staining. Acid production by lactobacilli and S. mutans single- and dual-species biofilms at different time intervals were analyzed using an Orion pH meter. Results: There was no inhibition of S. mutans growth by L-GG or L-M72 on THY agar plates; inhibition was noted only on MRS agar plates. L-GG was able to reduce S. mutans biofilm iii formation in direct assay but did not inhibit the biofilm formation in the indirect assay. In addition, the dual-species biofilm showed similar levels of acid production as lactobacilli single-species biofilms. Conclusions: Probiotic lactobacilli may prevent ECC development by inhibiting the growth and biofilm formation of S. mutans only under favorable conditions. Further studies will evaluate the in vivo effects of L-GG on S. mutans-induced caries development in animal models.4 0Item Restricted Early-life snack and dietary supplement intake among underserved children and their role in early childhood caries(Saudi Digital Library, 2023-05-12) Alkadi, Ahmed; Xiao, JinIntroduction: Early childhood caries (ECC) is one of the most diseases in young children in the United States. Cariogenic microbes and snack intake may be linked to the development of ECC. Snack and supplement intake may vary oral PH properties and offer nutrients for bacterial growth and consequently affecting the colonization of cariogenic microbes. However, the relationship between snack and supplement intake and cariogenic microbes is largely unclear. Objectives: To assess the snack and diet supplement consumption among underserved birth cohort in the first two years of life and to assess the association between snacks and supplement intake and oral cariogenic microorganisms (S. mutans, Candida) carriage in early life. Methods: A prospective birth cohort was included in the analyses if the enrolled children had data on snack intake and cariogenic microorganisms (n=127). A questionnaire was used to collect the amount and frequency of intake of snacks and drinks at the 12-, 18- and 24-month visits. Diet supplement prescriptions were abstracted from medical records. Saliva and plaque were collected at the same time points to assess the quantity of S. mutans and Candida carriage Results: Overall, 25.4% of children who participated developed ECC by 2 years of age. At 24 months, the detection of S. mutans was nearly 50%, while C. albicans remained stable at 20% since birth. S. mutans was found in 60% of plaque samples, while C. albicans was found in only 20% at 24 months. Chips and fresh fruit were associated with an increased risk of C. albicans colonization (p<0.05). Cereals with milk were associated with an increased risk of S. mutans colonization (p<0.05). Yogurt appeared to be protective against C. albicans colonization, as well as Vitamin D was a protective factor against S. mutans colonization (p<0.05). Conclusion: Certain snacks and drinks were associated with the colonization C. albicans and S. mutans in early life. Intriguingly, yogurt and vitamin D were linked to reducing the colonization of C. albicans and S. mutans. Further investigation is needed to elucidate the underlying mechanisms involved in these relationships.39 0