Browsing by Subject "Biofilm recovery"

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    Anti-Caries Efficacy of Fluoride at Increasing Maturation of a Microcosm Biofilm
    (2019-08) Ayoub, Hadeel Mohammed; Lippert, Frank; Gregory, Richard L.; Martinez Mier, E. Angeles; Anderson, Gregory
    Dental biofilm is a main contributing factor in the initiation and progression of dental caries. The maturation of dental biofilms is expected to alter the anti-caries efficacy of fluoride compounds. In the first aim, we conducted a series of modeldevelopment experiments to test different variables to standardize a reproducible in-vitro microbial caries model. We evaluated: surface conditioning using saliva; sucrose concentrations and caries lesion severity; growth media conditions and mineral saturation; dental substrate types; pH cycling protocol characteristics. In the second aim, we used the developed model to evaluate the changes in the anti-caries efficacy of three fluoride compounds (Sodium fluoride (NaF); Stannous fluoride (SnF2); Amine fluoride (AmF); and deionized water (DIW- negative control)) at increasing maturation of a microcosm biofilm. We continued the pH cycling protocol for 4 days, 8 days, and 12 days. We tested biofilm cariogenicity and carious lesion severity at each maturation stage. In the third aim, we used the developed model to test the effect of different exposure periods (early vs. late exposure) of the biofilm to three fluoride compounds (NaF, SnF2, AmF, DIW) in comparison to DIW. We also evaluated the recovery of biofilm cariogenicity with each exposure period. We evaluated, for each exposure period and recovery stage, biofilm cariogenicity and carious lesion severity. We analyzed the relationships between different variables (biofilm age, fluoride compound type, exposure period) using ANOVA models. In conclusion: 1. The present model allows testing the effect of biofilm maturation on the anti-caries efficacy of fluoride compounds. 2. Biofilm maturation plays an important role in increasing biofilm tolerance against fluoride treatment; it could also influence the selection of fluoride compounds to achieve optimum cariostatic effect. 3. Exposure period, and type of fluoride compound, both influence the biofilm tolerance to fluoride anti-caries effect; they may also result in a sustainable release of fluoride over time.
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    The influence of biofilm maturation on fluoride’s anticaries efficacy
    (Springer, 2022-02) Ayoub, Hadeel M.; Gregory, Richard L.; Tang, Qing; Lippert, Frank; Biomedical Sciences and Comprehensive Care, School of Dentistry
    Objectives (1) To explore the influence of biofilm maturation and timing of exposure on fluoride anticaries efficacy and (2) to explore biofilm recovery post-treatment. Methods Bovine enamel specimens were utilized in a pH cycling model (28 subgroups [n = 18]). Each subgroup received different treatments [exposure]: sodium fluoride [NaF]; stannous fluoride [SnF2]; amine fluoride [AmF]; and de-ionized water [DIW], at a specific period: early: days 1–4; middle: days 3–6; and late: days 7–10. During non-exposure periods, pH cycling included DIW instead of fluorides. Objective 1: part 1 (cycling for 4, 6, or 10 days). Part 2 (cycling for 10 days). Objective 2: early exposure: three sample collection time points (immediate, 3 days, and 6 days post-treatment); middle exposure: two sample collection time points (immediate, 4 days post-treatment). The enamel and biofilm were analyzed ([surface microhardness; mineral loss; lesion depth]; [lactate dehydrogenase enzyme activity; exopolysaccharide amount; viability]). Data were analyzed using ANOVA (p = 0.05). Results Objective 1: Early exposure to fluorides produced protective effects against lesion progression in surface microhardness and mineral loss, but not for lesion depth. Objective 2: Early exposure slowed the demineralization process. SnF2 and AmF were superior to NaF in reducing LDH and EPS values, regardless of exposure time. They also prevented biofilm recovery. Conclusion Earlier exposure to SnF2 and AmF may result in less tolerant biofilm. Early fluoride treatment may produce a protective effect against demineralization. SnF2 and AmF may be the choice to treat older biofilm and prevent biofilm recovery. Clinical relevance The study provides an understanding of biofilm-fluoride interaction with mature biofilm (e.g., hard-to-reach areas, orthodontic patients) and fluoride’s sustainable effect hours/days after brushing.